"Boarding school for children with visual impairments"
IN THE WORLD
INDICATORS
| INTRODUCTION | ||
| HISTORY OF DISCOVERY OF INDICATORS | 4 - 5 |
|
| CHEMICAL INDICATORS | 6 - 8 |
|
| III. | NATURAL INDICATORS | 9 - 10 |
| APPLICATION OF INDICATORS | ||
| Biochemical role of indicators and application in medicine | ||
| Application of natural indicators in the national economy | ||
| The use of indicators in everyday life | ||
| 1 4 - 18 |
||
| Preparation of natural indicators from plant materials | ||
| Determination of the environment of some household chemicals using the resulting indicator | ||
| Determination of the medium of solutions of some fermented milk products | ||
| CONCLUSION | ||
| LIST OF SOURCES USED |
INTRODUCTION
Indicators are widely used in chemistry, including in school. Any student will tell you what phenolphthalein, litmus or methyl orange is. When I got acquainted with acids and bases, I learned that when one or another indicator is added to an acidic or alkaline medium, the solutions change their color. Therefore, indicators are used to determine the reaction of the medium (acidic, alkaline or neutral). We were also told that the juices of brightly colored berries, fruits and flowers have the properties of acid-base indicators, since they also change their color when the acidity of the environment changes.
I was interested in the question: what plants can be used as indicators? Can you prepare herbal indicator solutions yourself? Are homemade indicators suitable for home use, for example, to determine the environment of food or household chemicals in order to identify their negative effects on the skin of the hands? Think, relevance of the topic lies in the fact that the properties of plant objects can be used for applications in various fields of science, for example, such as chemistry.
Hypothesis: solutions of herbal indicators can be prepared independently and used at home to determine the medium of some drinks and detergent solutions.
Objective: To study the effect of chemical and natural indicators in various environments.
Tasks:
Examine literary sources on the topic;
Consider the classification of indicators;
Draw certain conclusions on the use of indicators in everyday life and nature;
Learn to isolate indicators from natural raw materials;
Investigate the effect of natural indicators in various environments (to determine the environment of solutions of some food products, berry juices and solutions of dishwashing detergents).
I ... HISTORY OF DISCOVERY OF INDICATORS
For the first time substances that change color depending on the environment were discovered in the 17th century by the English chemist and physicist Robert Boyle, who conducted thousands of experiments. Here is one of them. 
Candles were burning in the laboratory, and something was boiling in the retorts when the gardener walked in inappropriately. He brought a basket of violets. Boyle was very fond of flowers, but the experiment had to begin. He took some flowers, sniffed them and put them on the table. The experiment began, the flask was opened, and caustic steam poured out of it. When the experiment was over, Boyle accidentally glanced at the flowers, they were smoking. To save the flowers, he dipped them into a glass of water. And - what a miracle - violets, their dark purple petals, turned red. Accidental experience? An accidental find? Robert Boyle would not be a real scientist if he passed such an incident. The scientist ordered the assistant to prepare solutions, which were then poured into glasses and dropped a flower into each. In some of the glasses, the flowers immediately began to turn red. Finally, the scientist realized that the color of the violets depends on what substances are contained in the solution. Then Boyle wondered what other plants would show, not violets. 
He prepared an aqueous infusion of litmus lichen for his experiments. The bottle in which he kept the infusion was needed for hydrochloric acid. After pouring out the infusion, Boyle filled a bottle with acid and was surprised to find that the acid turned red. Having become interested in this, Boyle added a few drops of litmus infusion to an aqueous solution of sodium hydroxide for testing and found that in an alkaline medium the litmus turns blue.
Experiments followed one after another, cornflowers and other plants were tested, but still the best results were obtained with experiments with litmus lichen. So, in 1663, the first indicator for the detection of acids and bases was discovered, named after the lichen by the litmus.
In 1667, Robert Boyle proposed to impregnate filter paper with a decoction of tropical lichen - litmus, as well as decoctions of violets and cornflowers. Robert Boyle called the dried and cut "tricky" papers indicators, which in Latin means "pointer", as they indicate Wednesday solution. 
It was the indicators that helped the scientist discover a new acid - phosphoric, which he obtained by burning phosphorus and dissolving the resulting white product in water.
Litmus has become the oldest acid-base indicator. I must say that the very coloring matter litmus was known in Ancient Egypt and Ancient Rome. It was extracted from some species of lichens growing on the rocks of Scotland and used as a purple paint, but over time, the recipe for its preparation was lost. 
In 1640, botanists described heliotrope - a fragrant plant with dark purple flowers, from which the coloring matter was also isolated. This dye, along with the juice of the violet, also became widely used by chemists as an indicator, which was red in an acidic medium and blue in an alkaline medium. 
Later, in the middle of the 19th century, chemists learned to artificially synthesize acid-base indicators. So in 1871, the German organic chemist Adolph von Bayer, the future Nobel Prize winner, was the first to synthesize phenolphthalein.
Nowadays, several hundred acid-base indicators, artificially synthesized, are known.
II ... CHEMICAL INDICATORS
The word "indicator"it is used in various fields of human activity - mechanics, mathematics, biology, ecology, economics, social, social sciences and others.
Indicator(from lat insky indicator - pointer) is a device, device, information system, substance or object that displays changes in any parameter of a controlled process or state of an object in a form that is most convenient for direct perception by a person visually, acoustically, tactilely or in another easily interpreted way. We will only consider chemical indicators.
Chemical indicators are substances that change color, luminescence or form a precipitate when the concentration of any component in solution changes. They are of natural and chemical origin. Indicators are used most often to establish the end of a chemical reaction or the concentration of hydrogen ions by an easily noticeable sign. Chemical indicators are usually divided into several groups.
The school uses the most common acid-base indicators. Their advantage is low cost, speed and clarity of research. These are soluble organic compounds that change their color depending on the concentration of hydrogen ions H + (pH of the medium). This happens because indicator molecules have different structures in acidic and alkaline environments. An example is the well-known indicator phenolphthalein. In an acidic medium, this compound is in the form of undissociated molecules and the solution is colorless, and in an alkaline medium it is in the form of ions and the solution has a crimson color. Such indicators sharply change their color in rather narrow pH ranges.
Universal indicators are mixtures of several individual indicators, selected so that their solution alternately changes color, passing all the colors of the rainbow when the acidity of the solution changes over a wide pH range.
pH - pH value. This concept was introduced by the Danish chemist Sørensen for the exact numerical characterization of the solution medium and proposed a mathematical expression to determine it:
pH = -lg.
The nature of the environment is of great importance in chemical and biological processes. Depending on the type of medium, these processes can proceed at different speeds and in different directions. Therefore, in many cases it is important to determine the solution environment as accurately as possible. At pH = 7 - the medium is neutral, at pH 7 - alkaline. The environment of the test solution can be approximately determined by the color of the indicators.
The most common indicators are litmus, phenolphthalein and methyl orange.
The very first acid-base indicator appeared litmus... In fact, natural litmus is a complex mixture. It is a black powder, soluble in water, 95% alcohol, acetone, glacial acetic acid. Its main components are: azolitmin (C 9 H 10 NO 5) and erythrolithmin (C 13 H 22 O 6). 
The color of litmus in different environments changes as follows:
Phenolphthalein C 20 H 14 O 4 (sold in a pharmacy under the name "purgen") is a white fine crystalline powder, soluble in 95% alcohol, but practically insoluble in water. It is used in the form of an alcohol solution, acquires a crimson color in an alkaline medium, and is colorless in a neutral and acidic medium. 
Methyl orange, C 14 H 14 N 3 O 3 SNa, - crystalline orange powder, moderately soluble in water, insoluble in organic solvents. Methyl orange is truly orange in a neutral environment. In acids, its color becomes pink-raspberry, and in alkalis - yellow. 
Depending on the acidity of the medium, changes color and dye brilliant green(its alcohol solution is used as a disinfectant - brilliant green). In a strongly acidic medium, its color is yellow, and in a strongly alkaline medium, the solution becomes discolored.
In addition to acid-base indicators, other types of indicators are also known: adsorption, complexometric , fluorescent, isotopic, redox and others.
universal indicator paper. It is based on mixtures of indicators that allow determining the pH value of solutions in a wide range of concentrations (1-10; 0-12). Solutions of such mixtures - "universal indicators" are usually impregnated with strips of "indicator paper", with the help of which it is possible to quickly (with an accuracy of tenths of pH) determine the acidity of the investigated aqueous solutions. For a more accurate determination, the color of the indicator paper obtained upon application of a drop of solution is immediately compared with a reference color scale. 
III ... NATURAL INDICATORS
Acid-base indicators are not only chemical. They are around us, but usually we don’t think about it. When there are no real chemical indicators, then homemade indicators from natural raw materials can be successfully used to determine the medium of solutions.
The starting material can be geranium flowers, peony or mallow petals, iris, dark tulips or pansies, as well as raspberries, blueberries, chokeberries, cherry juices, currants, grapes, buckthorn and bird cherry fruits.
These natural indicators contain colored substances (pigments) that can change their color in response to a particular stimulus. And, getting into an acidic or alkaline environment, they clearly signal this.
These pigments are primarily anthocyanins... They are (predominantly) red in an acidic environment and blue or green in an alkaline environment. Example:
| Alkali solution | |||
| Acid solution |
It is anthocyanins that impart various shades of pink, red, blue and purple to many flowers, fruits and autumn leaves. This color often depends on the pH of the cell content, and therefore can change with ripening of fruits, flowering of flowers and wilting of leaves.
Anthocyanins are unstable compounds; plant cells usually contain several different anthocyanins, and their manifestation is associated with the chemical composition of the soil and the age of the plant.
Ordinary tea is also an indicator. If lemon juice is dropped into a glass of strong tea or a few crystals of citric acid are dissolved, the tea will immediately become lighter. If you dissolve baking soda in tea, the solution will darken (you should not drink such tea, of course). Hibiscus tea produces much brighter colors.
An indicator is also ordinary ink, which, under the influence of acid, changes its color from violet to green, and again acquires a violet color when the acid is neutralized with alkali.
Beet juice in an acidic environment changes its ruby color to bright red, and in an alkaline environment - to yellow. Knowing the properties of beetroot juice, you can make the color of the borscht bright. To do this, add a little vinegar or citric acid to the borscht.
Here is a list of plants whose leaves or fruits can be used to make natural indicators.
| Grapes red Cherries, berry juice Geranium pink, petals Blueberries, berries Hydrangea Delphinium petals Strawberries, berries Red cabbage, juice Curry powder (turmeric) Horse chestnut, leaves Onion peel Poppy, petals Daisies, petals |
Carrots, juice Petunia, petals Peony red, petals |
While on vacation in summer, you can dry flower petals and berries, from which you can prepare solutions as needed, and thus provide yourself with indicators.
Juices or decoctions of brightly colored fruits or other plant parts used as natural indicators should be stored in a dark container. Unfortunately, natural indicators have a serious drawback: their decoctions quickly deteriorate - they turn sour or moldy. Therefore, in chemical laboratories, synthetic indicators are used, which sharply change their color in rather narrow pH ranges.
IV ... APPLICATION OF INDICATORS
Indicators allow you to quickly and accurately monitor the composition of liquid media, monitor changes in their composition or the course of a chemical reaction.
As already mentioned, there are a lot of natural pigments in plants, natural indicators, most of which are anthocyanins.
Since anthocyanins have good indicator properties, they can be used as indicators for identifying acidic, alkaline or neutral environments, both in chemistry and in everyday life. Both the behavior of substances and the nature of the reaction often depend on the acidity of the medium.
Natural indicators are used in many areas of human activity: in medicine and ecology, in agriculture and the national economy, in the food industry and in everyday life.
Anthocyanins are also used in cosmetics, because have a stabilizing effect and are collagens in the food industry as an additive E163 as natural dyes. They are used in the production of confectionery, beverages, yoghurts and other food products.
1. Biochemical role of indicators and application in medicine
The data of recent years indicate that the dyes of plants play a huge biochemical role, have a variety of therapeutic effects and have a beneficial effect on the human body.
Anthocyanins are powerful antioxidants that are 50 times stronger than vitamin C. Many studies have confirmed the benefits of anthocyanins for vision. The highest concentration of anthocyanins is found in blueberries. Therefore, preparations containing blueberries are most in demand in medicine.
Forming complexes with radioactive elements that have a detrimental effect on our body, anthocyanins contribute to their rapid elimination from organisms. Thus, anthocyanins are the guarantors of a long and healthy cell life, which means they extend our life as well. They have a protective effect on blood vessels, reducing their fragility, helping to lower blood sugar levels.
Entering the human body with fruits and vegetables, anthocyanins exhibit an effect similar to vitamin P; they maintain a normal state of blood pressure and blood vessels, preventing internal hemorrhages. Anthocyanins are required by brain cells, improve memory.
Anthocyanins have unique properties - they suppress the growth of tumors. For example, recent studies have shown that eating anthocyanins can help reduce the risk of cancer of the esophagus and rectum. Prepared from plants containing anthocyanins, aqueous and acidified infusions for several hours destroyed the bacteria of dysentery and typhoid fever. Anthocyanins help prevent the development of cataracts and generally have a beneficial effect on the entire body. Therefore, vegetables and fruits of bright colors are considered beneficial for the body.
2. Application of natural indicators in the national economy
Besides medicine, anthocyanins are also used in other fields. National economy... For example, in agriculture, to assess the chemical composition of the soil, the degree of its fertility, in the exploration of minerals. By adding a handful of earth to the anthocyanin solution, one can make a conclusion about its acidity, because on the same soil, depending on its acidity, one type of plant can give a high yield, while others will be oppressed.
“Or take at least the well-known potatoes. It has a different color of peel, eyes, seedlings and pulp. The difference in color of a potato depends on the pigments it contains. Colored potato tubers, as a rule, are richer in substances necessary for our body. So, for example, tubers with yellow flesh have a high content of fat, carotenoids, riboflavin and a complex of flavonoids. "
“Due to the ability of anthocyanins to change their color, one can observe a change in the color of potato tubers, depending on the use of mineral fertilizers and pesticides. When phosphorus fertilizers are applied, the potatoes turn white, potassium sulfate gives a pink color. The color of tubers changes under the influence of pesticides containing copper, iron, sulfur, phosphorus and other elements. Other plants containing natural indicators have similar properties. That allows you to assess the environmental situation. In environmental monitoring of pollution, the use of plants containing natural indicators often provides more valuable information than the assessment of pollution by instruments. In addition, this method of monitoring the state of the environment is simpler and more economical ”(NN Tretyakov. Textbook on agronomy).
3. The use of indicators in everyday life
Herbal indicators can be used in everyday life.
Indicators help to determine the environment of solutions of various household chemicals and cosmetics, to remove plant stains.
Even housewives use indicators to make the borscht bright red - a little food acid is added to it before the end of cooking - acetic or citric; the color changes right before our eyes.
It has long been in vogue to write invitations on flower petals; but they wrote them, depending on the flower and the desired color of the inscription, with an acid or alkali solution, using a thin pen or a pointed stick.
Back in the last century, the reaction of iodine with starch (as a result of which everything turns blue) was used to catch unscrupulous traders who added wheat flour to sour cream "for thickness". If iodine tincture is dropped on a sample of such sour cream, the blue staining will immediately reveal the catch.
Previously, litmus was used as a dye, but when synthetic dyes were invented, the use of litmus was limited. For this purpose, strips of filtered paper soaked in litmus solution are used.
V
1. Preparation of natural indicators
from vegetable raw materials
Tasks:
1. Obtain natural indicators from available natural objects. 2. Create a color change scale for each indicator.
Object of study:
Subject of study:
Research methods:
From the literature, I learned that you can prepare an extract of natural indicators different ways- boiling in water or extraction with any solvent, for example, alcohol. I prepared the indicators by boiling.
Lingonberries, cranberries, black currants, beets, carrots, turmeric and black tea were selected as natural indicators.
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| cowberry | black currant |
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| turmeric, black tea |
1. Manufacturing of indicators.
To prepare herbal indicators, I took 50 g of raw materials, grinded, filled in 100 ml of water and boiled for 1-2 minutes. This leads to the destruction of cell membranes, and anthocyanins freely leave the cells, staining the water. The resulting decoctions were cooled and filtered. In order to prevent spoilage, alcohol was added to the resulting filtrate in a 2: 1 ratio.
2. Exploring the Effect of Indicators in different environments, drawing up a color change table.
Having received the indicator solutions, I checked what color they have in different environments.
Several drops of each sample were added to solutions of hydrochloric acid HCl (acidic medium) and sodium hydroxide NaOH (alkaline medium).
Conclusion. All indicators changed their color in acidic and alkaline environments. Indicators from beets, black currants, lingonberries and cranberries have shown themselves better. Not all substances have pronounced indicator properties. Black tea changes color only in acid, and carrots and turmeric only in alkaline. All research data are included in the table:
| Object under study | Initial color | Acid staining | Coloring in alkali |
| Lingonberry berries | raspberry | ||
| Cranberries | raspberry | ||
| Black currant berries | raspberry | ||
| burgundy | hot pink | yellow-green |
|
| orange | light orange | ||
| brown |
|||
| Black tea | brown | dark brown |
Here are my top indicators
2. Determination of the environment of some household chemicals using the obtained indicators
Target: using the obtained indicators to investigate cosmetic-hygienic and detergents.
Equipment: samples of detergents and cosmetics and hygiene products; plant indicators (from lingonberry, cranberry, black currant and beet); test tubes.
Experience progress: I dissolved selected samples of detergents and household chemicals in water, and alternately added solutions of my indicators to the resulting solutions. The research results are listed in the table.
| Test substance | black currant | cowberry | |||
| Oxygen gel for enamel, acrylic and granite. SANELIT CJSC "Ashot" | pale pink | raspberry pink | raspberry pink | burgundy brown | Solution medium neutral, slightly acidic |
| Glass cleaner (with our alcohol) MrMuscule | pale pink | pale pink | dirty pink | brown green | The solution medium is weakly alkaline |
| Conditioning shampoo. Clean line | crimson | Solution medium neutral |
|||
| Ordinary soap | pale pink | pale pink | brown green | The solution medium is weakly alkaline |
Research results:
Glass cleaner and laundry soap have a slightly alkaline solution, so these products should not get into the eyes and destroy the natural defenses of the skin.
In biology and chemistry lessons, I learned that the outer surface of the epidermis is covered with a microscopically thin layer - an acid mantle. Many biochemical processes take place in the epidermis. As a result, acids are formed - lactic, citric and others. Plus to this: sebum and sweat. All this constitutes the acidic mantle of the skin. Therefore, normal skin is acidic, with skin pH averaging 5.5.
When using detergents with an alkaline environment, we disrupt the normal acidic environment of the skin of the hands. To protect the skin of the hands from negative impact such funds, you need to work with them only with gloves. Better yet, use other means: for example, wash your hands with good toilet soap or gel, or baby soap, in which substances neutralizing alkali have been added. They are less irritating to the skin.
The shampoo in my family is correct, the environment of its solution is close to that of the scalp - it is completely safe.
3. Determination of the medium of solutions of some
fermented milk products
I also checked the reaction of the environment of fermented milk products available in our home. But since the natural indicator solutions ran out, I worked with a paper universal indicator. Having dipped the indicator strip into kefir and homemade yogurt, I noticed that the piece of paper turned pink. I have proven acid in these foods.
These are lactic and other organic acids, which enhance the secretion of gastric juice, improve the functioning of the intestines, and normalize its microflora. Scientists argue that fermented milk cultures are easier, in comparison with natural milk, to be absorbed by the body and prevent the reproduction of harmful pathogenic microbes that cause putrefactive processes.
It's good that our family loves such products.
CONCLUSION
From literary and Internet sources, I learned about the actions of chemical and natural indicators in various environments, i.e. reached his main goal... I learned into which groups the indicators are divided, how they behave in acidic, basic and alkaline environments. It turns out that indicators can be used for a variety of purposes. For example, to remove a stain from berries, you first need to wash the thing in an acidic environment, and only then with a regular detergent. And you can also use indicators in order to use them to determine the environment of detergents and select the most acceptable detergent.
After conducting a series of experiments, I became convinced that the indicators are in fact substances that change color when the concentration of hydrogen ions in the solution changes, and confirmed my hypothesis.
In the modern world, with a huge variety of chemicals, you need to know the rules correct use of these substances. Do not neglect the instructions for use.
After doing my research, I came to the following conclusions:
Many natural plants possess the properties of acid-base indicators that can change their color depending on the environment in which they enter. These are the so-called natural indicators, brightly colored flowers and fruits of plants;
Solutions of herbal indicators can be used, for example, as acid-base indicators for determining the environment of solutions of hygienic detergents and the quality of products at home;
Self-made indicators from natural raw materials can be used in chemistry lessons in schools if there is a problem with providing the school with chemical reagents.
Unfortunately, almost all natural indicators have a serious drawback: their decoctions deteriorate rather quickly, so more stable alcohol solutions are often used. On the positive side is that they are environmentally friendly and can be prepared and used at home.
I hope that my work will attract the attention of students and teachers, since the information obtained can be used in a narrowly applied direction, for example, in the household and in the country. And I also hope that my work will contribute to the development of curiosity and observation in the children.
1. Plant indicators can be used in everyday life. Beet juice in an acidic environment changes its ruby color to bright red, and in an alkaline environment - to yellow. Knowing the properties of beetroot juice, you can make the color of the borscht bright. To do this, add a little vinegar or citric acid to the borscht.
2. To determine the composition of drugs that are used for treatment, you can use natural indicators. Many medicines are acids, salts and bases. Having studied their properties, you can protect yourself. For example, aspirin (acetylsalicylic acid) and many vitamins should not be taken on an empty stomach, as the acids in them will damage the stomach lining.
3. The results of research work can be used to determine the medium of various solutions, for example, dairy products, broths, lemonade and others, as well as to determine the acidity of the soil, since depending on this, one type of plant can give a high yield, while others will oppressed.
4. "Folk" method for determining the acidity of the soil. Place 3-4 black currant or cherry leaves in a glass dish and pour a glass of boiling water over them. When the water cools down, throw a lump of earth into it. If the water turns red - the soil is definitely acidic, turns blue - slightly acidic, and if it turns green - neutral.
5. Detergents for dishes have an alkaline environment and when using them, it is necessary to use rubber gloves to protect the skin of the hands from negative effects, since the alkaline environment destroys the acid mantle of the epidermis.
LIST OF SOURCES USED
Alikberova L.Yu. Entertaining chemistry. - M .: AST-PRESS, 2002.
Alikberova L.Yu. Entertaining chemistry. A book for students, teachers and parents. - M .: AST-PRESS, 1999.
Baykova V.M. Chemistry after school. - Petrozavodsk: Karelia, 1984.
Balaev I.I. Home experiment in chemistry. (Manual for teachers) - M .: Education, 1977.
Gabrielyan O.S. Chemistry. 11 class. Basic level: textbook for educational institutions. - M .: Bustard. 2008.
Kremenchug M. Chemistry. - M .: Philological Society "Slovo", 1995.
A.P. Kreshkov Fundamentals of Analytical Chemistry, 3rd ed., Vol. 2 - M., 1971.
Leenson I.A. Entertaining chemistry. - M .: ROSMEN, 2001.
9. Nazarova T.S., Grabetsky A.A. Chemical experiment at school. - M. 1987.
10. Scientific - practical journal "Chemistry for schoolchildren", No. 4, 2007.
11. Nifantyev E.E. Extracurricular work in chemistry using chromatography.- Moscow: Education, 1982.
12. Savina L.A. I get to know the world. Children's encyclopedia. Chemistry. - M .: AST, 1996.
13. Stepin B.D., Alikberova L.Yu. Entertaining tasks and spectacular chemistry experiments. - M .: Bustard, 2002.
14. Pilipenko A.T. Handbook of Elementary Chemistry. - Kiev, Naukova Dumka. 1973.
15. Educational-methodical newspaper for teachers of chemistry "September 1", №22, 2007.
16. Khramov V.A. Analytical biochemistry. - Volgograd: Uchitel Publishing House, 2007.
17. Shtempler G.I. Chemistry at your leisure. - M .: Education, " Educational literature", 1996.
18. Encyclopedic Dictionary of a Young Chemist. - M .: Pedagogy, 1982.
Internet resources:
1.http: //www.xumuk.ru/encyklopedia/1684.html
3.http: //ru.wikipedia.org/wiki.
4.http: //www.alhimik.ru
5.http: //www.planetseed.com/ruru
6.http: // www. alchemic.ru. "Good advice".
View presentation content
"In the world of indicators"
In the world of indicators
Research project
8th grade student
Gogolev Sergey,
head Zakharova L.Yu.
Purpose of work: To study the effect of chemical and natural indicators in various environments
- study literary sources on the topic; consider the classification of indicators; draw certain conclusions on the use of indicators in everyday life and nature; learn to isolate indicators from natural raw materials; to investigate the effect of natural indicators in various environments.
- study literary sources on the topic;
- consider the classification of indicators;
- draw certain conclusions on the use of indicators in everyday life and nature;
- learn to isolate indicators from natural raw materials;
- to investigate the effect of natural indicators in various environments.
From the history of the discovery ...
Robert Boyle, English chemist
and a physicist of the 17th century, first discovered
color-changing substances
depending on the environment.
litmus
lichen
litmus
heliotrope
Indicator (from Latin indicator - pointer)
voltage indicator
dial indicator
indicator
battery charge
indicator
hidden wiring
sound level indicator
tire wear indicator
CHEMICAL INDICATORS
Chemical indicators are substances that change color, luminescence or form a precipitate when the concentration of any component in solution changes.
7 METHYLORANGE colorless red orange blue raspberry pink yellow "width =" 640 " Name
indicator
Neutral environment
LITMUS
PHENOLPHTHALEIN
Sour
c eda
colorless
Violet
Alkaline environment
METHYLORANGE
colorless
Red
Orange
blue
crimson
pink
yellow
Nowadays, chemists often use universal indicator paper
APPLICATION OF INDICATORS
Ecology
Food industry
Agriculture
NATURAL INDICATORS
The medicine
Household
Manufacture of cosmetics
The medicine
Anthocyanins are powerful antioxidants, 50 times stronger than vitamin C:
- remove radioactive substances, prolonging the life of cells;
- useful for vision;
- are required by brain cells,
- improve memory
- inhibit the growth of tumors.
Agriculture
Study of
soil fertility
Analysis
environmental
questions
Household tools analysis
chemistry and cosmetics
Adding food
the acid in the borscht will make it bright red
- Tasks :
- 1. Obtain natural indicators from available natural sites.
- 2. Draw up a scale of color change for each indicator.
- Object of study : natural plants with indicator properties.
- Subject of study: homemade herbal indicator solutions.
- Research methods:
- Study of popular science literature;
- Obtaining solutions of indicators and working with them.
1. Preparation of natural indicators from plant materials
including currants
cowberry
cranberry
beet
turmeric
carrot
Ch. tea
Indicator action table
Object under study
Initial color
Lingonberry berries
raspberry
Cranberries
Acid staining
Black currant berries
raspberry
pink
Coloring in alkali
green
raspberry
pink
Beet
Carrot
green
pink
burgundy
orange
green
hot pink
Turmeric
yellow-green
light orange
yellow
Black tea
yellow
brown
yellow
brown
yellow
dark brown
2. Determining the environment of some tools
household chemicals using
received indicators.
Test substance
cranberry
Oxygen gel for enamel, acrylic and granite.
SANELIT CJSC "Ashot"
pale pink
black currant
Glass cleaner
(with our alcohol)
M rMuscule
pale pink
raspberry pink
Conditioning shampoo.
Clean line
cowberry
raspberry pink
Ordinary soap
beet
pale pink
pink
crimson
pale pink
dirty pink
burgundy brown
Conclusion
brown green
pale pink
Solution medium
neutral, slightly acidic
brown
brown green
Solution medium neutral
The solution medium is weakly alkaline
Investigational funds
have an alkaline reaction of solutions
- The test dairy products have an acidic solution
Objects of research: 1. Natural substances that can be used for the preparation of acid-base indicators: juices of brightly colored fruits and berries, cell sap of flower petals of different plants, brightly colored peel of fruits and tree bark. 2. Solutions of substances used in Everyday life
Project objectives: 2. To study the method of preparation of natural indicators. 3. To determine experimentally the possibility of using natural indicators to determine the environment of household solutions (soap, shampoo, powder, tooth powder, tea, juice. Soil extract, etc.) 4. To study the chemical bases of natural indicators. 1. Consider the history of the discovery of some acid-base indicators.
Indicators (from the English indikate - to indicate) are substances that change their color depending on the environment of the solution. Indicators most widely used in the chemical laboratory Lacmus Phenolphthalein Methyl orange Universal - a mixture of several indicators Several hundred indicators are known today.
Pages of History Indicators were first discovered in the 17th century by the English chemist and physicist Robert Boyle. To understand how the world works, Boyle went through thousands of experiments. Here is one of them. Candles were burning in the laboratory, and something was boiling in the retorts when the gardener entered with a basket of violets. The experiment began, the flask was opened, and caustic steam poured out of it. Boyle glanced at the flowers, they were smoking; to save the flowers, he dipped them into a glass of water. And the flower petals turned from deep purple to red. The scientist ordered the assistant to prepare solutions, which were then poured into glasses. The scientist realized that the color of the violets depends on what solutions were in the glass. Then Boyle wondered what would show not violets, but other plants. The best results were obtained from experiments with litmus lichen. Robert Boyle
Litmus was known in Ancient Egypt and Ancient Rome, where it was used as a purple paint - a substitute for expensive purple. Then the litmus recipe was lost. Only at the beginning of the 14th century in Florence the purple paint-orseil was again discovered. Prepared as follows: 1. Lichens were crushed. 2. Moistened, added ash and soda to the mixture. 3. Placed in wooden barrels, added urine and kept for a long time Pages of history
The orseil-like coloring matter was isolated in the 17th century from heliotrope, a fragrant garden plant with dark purple flowers. From that time, thanks to R. Boyle, orseil and heliotrope began to be used in the chemical laboratory. And only in 1704 the German scientist M. Valentin called this paint a litmus. Modern production litmus 1. Lichens are crushed 2. Fermented in a solution of potash (potassium carbonate) and ammonia. 3. Add chalk and plaster.
Method for preparing homemade plant indicators To establish a method for preparing plant indicators, we have studied and investigated juices of brightly colored fruits and berries, cell sap of flower petals of different plants, such as: chamomile, rose hips, calendula, beetroot, peony, blueberry, black currant, tea, decoction of oak bark, Brussels sprouts. The best results were obtained using the following plants: blueberries and currants. 1. Prepared a decoction from the juice of blueberries or black currants. 2. To 30 g of berries added 1 tablespoon of hot water. 3. Bring the solution to a boil. 4.Cool, stirred for 2-3 minutes, let the solution settle for 1-2 minutes.
5.Filtered. For filtration, a funnel made from a plastic bottle and filter paper were used. 6. Cut the filter paper (1 cm wide, 4 cm long). 7. Soak the filter paper strips with the prepared broth for 2 minutes. 8. Dry the strips out of bright light. 9. Stored the prepared indicator papers in a dark container.
Characteristics of plant indicators Plant (part of it) pH = 1 (acidic medium) pH = 7 (neutral medium) pH = 13 (alkaline medium) Dark beans Red Purple Yellow-green Grapes (skin) Pink Lilac Yellow-green Azalea (flowers) Purple-red Pink Yellow Blueberries (berries) Red Blue Black currants (berries) Red Blue
Home experiment (results of the study of household solutions) Test solution Color Medium 1. Soil extract Red Sour 2. Juice "Good", apple Red Sour 3. Kefir "House in the village" Red Sour 4. Milk "House in the Village" Purple Neutral 5. Soap solution "Pure line, cosmetic soap" Blue Alkaline
Chemical bases of the action of pH indicators from plant extracts The action of natural indicators is based on the ability of anticyanides, which are a mixture of glycosides contained in flowers and fruits of plants, to form equilibrium structures in different environments. At low pH values, the characteristic form of anthocyanins is the oxonium ion (1), which gives the solution a pink-red color. As the acidity decreases, this structure turns into a colorless compound (2), and in an alkaline medium - into a quinoid compound (3), which has a blue color. Since all these processes are reversible, color transitions can be observed many times by changing the pH of the medium.
Conclusions from the experiment 1. This type of tea has high acidity, so people with high acidity of the stomach should not drink it. 2. The tested shampoo has a neutral environment, so it can be used for delicate baby skin. 3. The studied type of soap should not be used by people with dry skin, because this type of soap, having an alkaline reaction of the environment, will dry the skin. 4. The powder taken for research has pronounced basic properties. Therefore, you need to work with it carefully. It is better not to wash woolen and silk items in this powder. 5. The soil taken for research from the school garden has acidic properties, therefore, work should be carried out on its liming, because acidic soil adversely affects the development of plants.
Conclusions on the work 1. Chemistry is a science that is directly related to the practical activities of a person, it is no coincidence that the epigraph to the project was taken from the words of MV Lomonsov “Chemistry stretches far out its hands in human affairs”. 2. Considered the history of the discovery of some indicators and the chemical basis of pH indicators from plants. 3. Studied the method of preparation of pH indicators from plants. 4. We determined the environment of some household solutions with the help of home-made indicators.
Dear Guys! Thank you for your attention! We have made sure once again that at home we can prepare indicator papers and use them to determine the acidity of the environment of household solutions. Work on the project will continue next year
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"Natural Indicators" RESEARCH WORK
The work was carried out by 11th grade pupils of the Municipal Autonomous Educational Institution Lyubokhonskaya Secondary School named after twice Hero of the Soviet Union A.A. Golovachev, Gunko Elena Alekseevna and teacher of biology and chemistry Kovalchuk Elena Viktorovna.
Municipal autonomous educational institution Lyubokhonskaya secondary school named after twice Hero of the Soviet Union A.A. Golovachev.
smt. Lyubokhna, 2013
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CONTENT
Chapter 1. Introduction Chapter 2. Main part 2.1. From the history of indicators. Classification of indicators. 2.2. Natural indicators. Biochemical role of natural indicators. Requirements for indicators. Chapter 3. Experimental part 3.1. Methods of manufacturing indicators from natural raw materials. 3.2. Research results table. 3.3. Determination of the medium of solutions of dishwashing detergents using plant indicators. 4. Conclusion. 5. Recommendations. 6. Literature.
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1. Introduction
Indicators are substances that change their color depending on the reaction of the environment. The name "indicators" comes from the Latin word indicator, which means "pointer". In a chemical laboratory or at a factory, indicators in a visual form will tell you whether the chemical reaction has gone through to the end or not, it is enough to add one reagent to another, or you need to add more. When studying acids and bases in chemistry lessons, I learned that the juices of brightly colored berries, fruits and flowers have the properties of acid-base indicators, that is, they change their color when the acidity of the environment changes. I was interested in the question: what plants can be used as indicators? Can you prepare herbal indicator solutions yourself? And can the prepared indicator solutions be used to determine the reaction of the environment of dishwashing detergents in order to determine whether they have a negative effect on the skin of the hands. The relevance of the topic lies in the fact that the properties of plant objects can be used for application in various fields of science, such as, for example, chemistry.
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1. Introduction
Purpose of the work: with the help of research, to prove the presence of natural indicators in plant objects, to study their properties, to determine with their help the reaction of the environment of solutions of detergents for dishes. Research objectives: 1) To study literary sources on the topic; 2) Investigate natural objects for the presence of indicators; 3) Study the properties of indicators contained in natural objects; 4) Conduct a study to determine the reaction of the environment of solutions of dishwashing detergents. Objects of research: berries of cherry, strawberry, mountain ash, blueberry, lingonberry, blackberry, chokeberry, black currant; leaves of red cabbage, parsley, black currant; fruits: beets; flowers: red rose, red geranium, multi-colored carnation. Research hypothesis: if plants change color in different environments, then they can be used as indicators Research methods: 1. Study of scientific literature on this issue 2. Qualitative analysis. 3. Observation.
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2.1. From the history of indicators
The history of indicators begins in the 17th century. Back in 1640, botanists described heliotrope - a fragrant plant with dark purple flowers (see picture), from which the coloring matter was isolated. This dye, along with the juice of violets, has become widely used by chemists as an indicator. You can read about this in the works of the famous physicist and chemist of the 17th century Robert Boyle. In 1663 litmus was discovered - an aqueous infusion of lichen growing on the rocks of Scotland. Robert Boyle prepared an aqueous infusion of litmus lichen for his experiments. The bottle in which he kept the infusion was needed for hydrochloric acid. After pouring out the infusion, Boyle filled a bottle with acid and was surprised to find that the acid turned red. Having become interested in this, Boyle added a few drops of litmus infusion to an aqueous solution of sodium hydroxide for testing and found that in an alkaline medium the litmus turns blue. This is how the first indicator for the detection of acids and bases was discovered, named after the lichen by the litmus. Phenolphthalein, which is used in the form of an alcohol solution, acquires a crimson color in an alkaline medium, and is colorless in a neutral and acidic medium. The synthesis of phenolphthalein was first carried out in 1871 by the German chemist Adolph von Bayer, the future Nobel Prize laureate. As for the methyl orange indicator, discovered in 1887, it is indeed orange in a neutral environment. In acids, its color becomes pink-raspberry, and in alkalis - yellow.
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2.1. Classification of indicators
One of the most common are acid-base indicators, which change color depending on the acidity of the solution. This happens because indicator molecules have different structures in acidic and alkaline environments. An example is the well-known indicator phenolphthalein. In an acidic medium, this compound is in the form of undissociated molecules and the solution is colorless, and in an alkaline medium it is in the form of ions and the solution has a crimson color. In addition to acid-base, other types of indicators are also used. Redox indicators change their color depending on the presence of an oxidizing agent or a reducing agent in the solution. Such indicators are substances that themselves undergo oxidation or reduction, and the oxidized and reduced forms have different colors. For example, the oxidized form of diphenylamine is violet in color, while the reduced form is colorless. Complexometric indicators are widespread - substances that form colored complex compounds with metal ions. Some substances are adsorbed on the surface of the sediment, changing its color; such indicators are called adsorption indicators. When determining the environment of turbid or colored solutions, in which it is almost impossible to notice a change in the color of conventional acid-base indicators, fluorescent indicators are used. They glow (fluoresce) in a different color depending on the pH of the solution. It is important that the glow of the indicator does not depend on the transparency and its own color of the solution. Often, universal indicators are used - a mixture of several individual indicators selected so that their solution alternately changes color, passing all the colors of the rainbow when the acidity of the solution changes in a wide pH range (for example, from 1 to 11). Strips of paper are often impregnated with a solution of a universal indicator, which allow one to quickly (albeit with not very high accuracy) determine the pH of an analyzed solution by comparing the color of a strip moistened with a solution with a standard color scale.
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2.2 Natural indicators
If there are no real chemical indicators, then indicators isolated from natural raw materials can be successfully used to determine the medium of solutions. The starting material can be geranium flowers, peony or mallow petals, iris, dark tulips or pansies, as well as raspberries, blueberries, chokeberries, cherry juices, currants, grapes, buckthorn and bird cherry fruits. These natural indicators contain colored substances (pigments) that can change their color in response to a particular effect and, getting into an acidic or alkaline environment, they visually signal this. These pigments are, first of all, anthocyanins: in a neutral medium they acquire a purple color, in an acidic medium - a red color, in an alkaline medium - a green-yellow color. It is anthocyanins that impart various shades of pink, red, blue and purple to many flowers, fruits and autumn leaves. This color often depends on the pH of the cell content, and therefore can change with ripening of fruits, flowering of flowers and wilting of leaves Anthocyanins are unstable compounds; plant cells usually contain several different anthocyanins, and their manifestation is associated with the chemical composition of the soil and the age of the plant. Ordinary tea is also an indicator. If lemon juice is dropped into a glass of strong tea or a few crystals of citric acid are dissolved, the tea will immediately become lighter. If you dissolve baking soda in tea, the solution will darken (you should not drink such tea, of course). Hibiscus tea produces much brighter colors. An indicator is also ordinary ink, which, under the influence of acid, changes its color from violet to green, and again acquires a violet color when the acid is neutralized with alkali.
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2.2 Biochemical role of indicators
Entering the human body with fruits and vegetables, anthocyanins exhibit an effect similar to vitamin P; they maintain a normal state of blood pressure and blood vessels, preventing internal hemorrhages. Anthocyanins are required by brain cells, improve memory. Anthocyanins are powerful antioxidants that are 50 times stronger than vitamin C. Many studies have confirmed the benefits of anthocyanins for vision. The highest concentration of anthocyanins is found in blueberries. Therefore, preparations containing blueberries are most in demand in medicine.
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2.2 Requirements for indicators
For any substance to serve as an indicator, it must meet the following necessary conditions: 1) must be a weak acid or weak base; 2) its molecules and ions must have different colors; 3) their color must be extremely intense in order to be noticeable when a small amount of indicator is added to the test solution. Natural indicators have a serious drawback: their decoctions deteriorate rather quickly - they turn sour or moldy (alcohol solutions are more stable). Another drawback is the too wide range of color change. In this case, it is difficult or impossible to distinguish, for example, a neutral medium from a weakly acidic or slightly alkaline from a strongly alkaline one.
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3.1. Own research
During the summer I prepared indicators. Plants were used as the starting material. Extracts were obtained from all the collected plants one by one. For this, the fruits were crushed, poured with water and boiled for 1-2 minutes. Then the solution was cooled and filtered. The resulting filtrate was diluted with alcohol at the rate of two volumes of the filtrate and one volume of alcohol in order to protect it from deterioration. I prepared extracts from petals of flowers and leaves in the same way. Chemical vessels were used to prepare the indicators: test tubes, beakers, pipettes, funnels, filter paper, and a water bath. Distilled water, solutions with acidic and alkaline media were also required. Table vinegar (9%) served as an acidic solution, and a solution of washing (soda ash) soda served as an alkaline solution. The prepared plant indicators were tested when exposed to acidic and alkaline solutions. Fruits, petals, leaves, flowers of the following plants were examined: cherry, strawberry, blueberry, lingonberry, blackberry, chokeberry, beet, black currant, carnation, red rose, red cabbage, red geranium, parsley, mountain ash. The research results are listed in Table 1.
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3.2. Results of the study of indicator plants
TABLE 1:
RAW MATERIALS FOR INDICATOR PREPARATION NATURAL INDICATOR COLOR SOLUTION COLOR SOLUTION COLOR
RAW MATERIALS FOR PREPARING INDICATORS NATURAL COLOR OF THE INDICATOR in an acidic medium (pH> 7) in an alkaline medium (pH Cherry (berries) Dark red Bright red Dirty green
Strawberry (berries) Pink Orange Light brown
Rowan (berries) Red Raspberry Pink
Blueberries (berries) Light purple Violet Dirty green
Lingonberry (berries) Dark red Yellow Orange
Blackberries (berries) Dark purple Red Brown
Chokeberry (berries) Burgundy Red Dirty green
Beetroot (fruit) Ruby Bright red Yellow
Red cabbage (leaves) Dark purple Green Lilac
Black currant (berries) Burgundy Red Green
Black currant (leaves) Yellow-green Yellow Brown
Parsley (leaves) Yellow-green Light brown Yellow
Red rose (flowers) Pink Burgundy Bright red
Carnation (flowers) Brown Pale pink Yellow
Red geranium (flowers) Red Orange Light brown
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3.3. Determination of the medium of solutions of dishwashing detergents using vegetable indicators
In biology lessons, I learned that the outer surface of the epidermis is covered with a microscopically thin layer - an acid mantle. Many biochemical processes take place in the epidermis. As a result, acids are formed - lactic, citric and others. Plus to this: sebum and sweat. All this constitutes the acidic mantle of the skin. Therefore, normal skin is acidic, with skin pH averaging 5.5. When using alkaline dishwashing detergents, we disrupt the normal acidic environment of the skin of the hands. To protect the skin of the hands from negative effects, dish detergents should have a pH value corresponding to the pH value of the acid mantle of the epidermis. With the help of prepared solutions of natural indicators, I checked what kind of environment different dish detergents have.
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3.3. Reaction of the medium in dishwashing detergent solutions
TABLE 2:
No. Detergent for dishes Herbal indicator Color of indicator Solution medium
1 "Myth" Red cabbage broth Pale green Weakly alkaline
2 "Fairy" Red cabbage broth Green Alkaline
3 "AOS" Strawberry decoction Pale yellow Weakly alkaline
4 "Pril" Aronia berry decoction Pale pink Slightly acidic
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4. Conclusion
After my research work, I came to the following conclusions: - many natural plants have the properties of acid-base indicators, capable of changing their color depending on the environment in which they enter; - solutions of herbal indicators can be used, for example, as acid-base indicators for determining the medium of solutions of dishwashing detergents at home; - homemade indicators from natural raw materials can be used in chemistry lessons in schools, if there is a problem of providing the school with chemical reagents. According to the results of the study, the indicator properties of the objects under study were proved. Moreover, the following pattern is observed here - all these natural objects in an acidic environment are predominantly colored red, and in an alkaline environment - in green-yellow. And this proves that they do contain anthocyanins. This study showed that in nature there are such plant objects that change their color depending on the acidity of the environment. Therefore, we can call them natural indicators.
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1) Natural indicators can be used in chemistry lessons, elective courses. 2) Plant indicators can be used in everyday life. Beet juice in an acidic environment changes its ruby color to bright red, and in an alkaline environment - to yellow. Knowing the properties of beetroot juice, you can make the color of the borscht bright. To do this, add a little vinegar or citric acid to the borscht. 3) To determine the composition of drugs that are used for treatment, you can use natural indicators. Many medicines are acids, salts and bases. Having studied their properties, you can protect yourself. For example, aspirin (acetylsalicylic acid), many vitamins should not be taken on an empty stomach, as the acids in their composition will damage the stomach lining. 4) The results of research work can be used to determine the pH (pH) of various solutions, for example, dairy products, broths, lemonade and others, as well as to determine the acidity of the soil, since on the same soil, depending on its acidity, one species plants can produce high yields, while others will be oppressed. 5) Detergents for dishes "Myth", "Fairy", "AOS" have an alkaline and slightly alkaline environment and when using them, rubber gloves must be used to protect the skin of the hands from negative effects, since the alkaline environment destroys the acidic mantle of the epidermis; 6) In the poem of the famous English poet R.Kipling "Blue Roses", there are the following lines: Somehow, dear, I brought a whole heap of red roses. She did not take - and in tears, blue, find her roses. I shouldn't have traveled all over the world - there are no blue roses under the sun. Of course, there are no raspberry cornflowers and blue lilies of the valley, but you can give the flowers a fantastic color. Pour concentrated ammonia into a cylinder and place a red rose flower. After a few minutes, a color change can be observed. When interacting with vapors of ammonia, the color of the red rose turns blue.
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6. References
1.Alikberova L.Yu. Entertaining chemistry. - M .: AST-PRESS, 2002.2. Alikberova L.Yu. Entertaining chemistry. A book for students, teachers and parents. - M .: AST-PRESS, 1999.3. Oganesyan E.T. A guide to chemistry for university applicants. - M .: graduate School, 1998 4. Savina L.A. I get to know the world. Children's encyclopedia. Chemistry. - M .: AST, 1996. 5. New encyclopedic dictionary. - M .: Great Russian Encyclopedia. Rinol Classic, 2000. 6. Encyclopedic Dictionary of a Young Chemist. - M .: Pedagogika, 1982.7.Stepin B.D., Alikberova L.Yu. Entertaining tasks and spectacular chemistry experiments. - M .: Bustard, 2002.8. Internet resources. 9. Pilipenko A.T. "Handbook of Elementary Chemistry". Kiev "Naukova Dumka". 1973 Pages 164 -167. 10. Baykova V.M. "Chemistry after school". 1976 P. 90-95. 11. Scientific - practical journal "Chemistry for schoolchildren" No. 4 2007. p.60 12. Educational-methodical newspaper for teachers of chemistry "September 1", No. 22, 2007. 13. Balaev I.I. "Home experiment in chemistry." 14. Nazarova T.S., Grabetsky A.A. "Chemical experiment at school", Moscow. 1987 15. Information from the website alchemic.ru "Good advice".
MKOU Marshansk secondary school
Research work in chemistry
"Indicators in our life".
The work was carried out by pupils of the 8th grade
Sidorova Larisa
Kuryshko Anastasia
Burmatova Svetlana
Head: Sinitsina Margarita
Anatolyevna - chemistry teacher
2016 year
Introduction
Indicators opening history
Classification of indicators.
Natural indicators
Experimental part.
Conclusion.
Bibliography.
1. Introduction
In nature, we meet with various substances that surround us. This year we began to get acquainted with an interesting subject - chemistry. How many substances are there in the world? What are they? Why do we need them and what benefits do they bring?
We were interested in substances such as indicators. What are indicators?
In the lessons when studying the topic "The most important classes of inorganic compounds" we used indicators such as litmus, phenolphthalein and methyl orange.
Indicators (from English indicate-to indicate) are substances that change their color depending on the environment of the solution. Using indicators, you can determine the environment of the solution
We decided to find out whether it is possible to use those natural materials that are at home as indicators.
Objective:
Explore the concept of indicators;
Get acquainted with their opening and functions performed;
Learn to distinguish indicators from natural objects;
Investigate the effect of natural indicators in various environments;
Research methods :
Study of popular science literature;
Obtaining solutions of indicators and working with them
2. History of opening indicators
Indicators were first discovered in the 17th century by the English physicist and chemist Robert Boyle. Boyle conducted various experiments. One day, when he was doing another research, the gardener came in. He brought violets. Boyle loved flowers, but he needed to experiment. Boyle left the flowers on the table. When the scientist finished his experiment, he accidentally looked at the flowers, they were smoking. To save the flowers, he dipped them into a glass of water. And - what a miracle - violets, their dark purple petals, turned red. Boyle became interested and conducted experiments with solutions, each time adding violets and observing what happens to the flowers. In some of the glasses, the flowers immediately began to turn red. The scientist realized that the color of the violets depends on what kind of solution is in the glass, what substances are in the solution. The best results were obtained from experiments with litmus lichen. Boyle dipped ordinary paper strips into the infusion of litmus lichen. I waited until they were soaked in infusion, and then dried them. These tricky pieces of paper Robert Boyle called indicators, which in Latin means "pointer", as they indicate the environment of the solution. It was the indicators that helped the scientist discover a new acid - phosphoric, which he obtained by burning phosphorus and dissolving the resulting white product in water. Currently, the following indicators are widely used in practice: litmus, phenolphthalein, methyl orange.
2. Classification of school indicators and how to use them
Indicators have different classifications . One of the most common are acid-base indicators, which change color depending on the acidity of the solution. Nowadays, several hundred artificially synthesized acid-base indicators are known, some of them can be found in the school chemistry laboratory.
Phenolphthalein (sold in a pharmacy under the name "purgen") - fine crystalline powder, white or white with a slightly yellowish sheen. Let's dissolve in 95% alcohol, practically insoluble in water. Colorless phenolphthalein in an acidic and neutral medium is colorless, and in an alkaline medium it turns crimson. Therefore, phenolphthalein is used to determine the alkaline environment.
Methyl orange - orange crystalline powder. We will moderately dissolve in water, we will easily dissolve in hot water, practically insoluble in organic solvents. Color transition of the solution from red to yellow.
Lacmoid (litmus) - black powder. Let's dissolve in water, 95% alcohol, acetone, glacial acetic acid. Color transition from red to blue.
Indicators are usually used by adding a few drops of an aqueous or alcoholic solution, or a little powder to the test solution.
Another application is using strips of paper soaked in an indicator solution or indicator mixture and dried at room temperature. Such strips are produced in a wide variety of versions - with a color scale applied to them - a color standard or without it.
3. Natural indicators
Acid-base indicators are not only chemical. They are around us, but usually we don’t think about it. These are herbal indicators that can be used in everyday life. For example, the juice of beetroot in an acidic environment changes its ruby color to bright red, and in an alkaline environment - to yellow. Knowing the properties of beetroot juice, you can make the color of the borscht bright. To do this, add a little vinegar or citric acid to the borscht. If lemon juice is dropped into a glass of strong tea or a few crystals of citric acid are dissolved, the tea will immediately become lighter. If you dissolve baking soda in tea, the solution will darken.
Juices or decoctions of brightly colored fruits or other plant parts are most often used as natural indicators. Such solutions must be stored in dark containers. Unfortunately, natural indicators have a serious drawback: their decoctions quickly deteriorate - they turn sour or moldy (alcohol solutions are more stable). In this case, it is difficult or impossible to distinguish, for example, a neutral medium from a weakly acidic or slightly alkaline from a strongly alkaline one. Therefore, in chemical laboratories, synthetic indicators are used, which sharply change their color in rather narrow pH ranges.
experimental part
What indicators can be used at home? To answer this question, we examined solutions of juices of fruits and flowers of plants such as Kalanchoe (orange, red and white flowers), carrots, blue and yellow onions (husks and the bulb itself), tulip (red flowers and green leaves), geranium (flowers are pink and white), dandelion, pansies, black currants and raspberries (berries). We prepared solutions of the squeezed juices of these plants and fruits, since the solutions quickly deteriorate, we prepared them immediately before the experiment as follows: we ground some leaves, flowers or fruits in a mortar, then added a little water. The prepared solutions of natural indicators were examined with a solution of acid (hydrochloric acid) and alkali (sodium hydroxide). All solutions taken for research changed or did not change their color depending on the medium. The results of the studies obtained were entered in the table.
| Object under study | Initial color of the solution in a neutral medium | Acid staining | Alkaline dyeing |
| Kalanchoe (orange flowers) | pale yellow | yellow | pale yellow |
| Kalanchoe (red flowers) | maroon | pink | emerald green |
| Kalanchoe (pink flowers) | lilac | pink | green |
| Tulip (flowers are red) | maroon | dark orange | yellow-green |
| Tulip (leaves) | light green | without changes | green |
| Blue onion (husk) | |||
| Blue onion (bulb) | |||
| Yellow onion (husk) | |||
| Yellow onion (bulb) | |||
| Carrots (juice) | orange | ||
| Beetroot (juice) | |||
| Dandelion | yellow-green | light yellow | dark yellow |
| Black currant berries | |||
| Raspberries | |||
| Geranium (bright pink flowers) | hot pink | hot pink | light brown |
| Geranium (white flowers) | white | light yellow | white |
| Pansies (purple flowers) | violet | hot pink | emerald green |
| Pansies (yellow flowers with a brown center) |
Karelian branch of the MOU Ust'inskaya secondary school of the Morshansk region. Natural indicators (research) Performed 8th grade student Melsitova Julia. Teacher: Polyakova E.N. teacher of geography and biology 2011 Content.1.Introduction pages 5 - 4 2. Main part pages 5 - 14 2.1. Theoretical part pp. 5 - 10 2.2. research part pages 10 - 14 3. Conclusion page 15 4. Literature page 16 Introduction. Nature is an amazing creation of the Universe. The natural world is beautiful, mysterious and complex. This world is rich in a variety of fauna and flora. this work dedicated to the unique properties of plants that never cease to amaze mankind. We will delve deeper into them inner world, we will establish their connection with such sciences as chemistry, biology and even medicine. So let's start with the simplest. The plant kingdom surprises us with its variety of color shades. The color palette is so varied that it is impossible to say how many flowers and their shades exist in the plant world. Thus, the question arises - what does the color of certain plants depend on? What is the structure of plants? What do they contain? And what are their properties? The further we plunge into the world of plants, the more and more we ask ourselves other questions. It turns out that the color of plants is determined by the chemical composition of the cellular content of each plant. Or rather, the so-called bioflavonoids are to blame. These are natural chemical compounds that give a certain color shade and properties to any plant. Therefore, there are many bioflavonoids. These include anthocyanins, xanthophylls, carotenoids, catechins, flavonols, flavonones, and others. The benefits of many plants are undeniable. Since ancient times, people have used plants as medicines. Therefore, it is not for nothing that folk medicine arose, based on the unique and medicinal properties of plants. Why we have chosen this topic. First, we are interested in the properties of plant objects. Second, what is their role in a science like chemistry? How are their indicator properties determined? And, thirdly, how you can use their properties for medicinal purposes. Therefore, we will consider flavonoids such as anthocyanins. Because they are ideal candidates for our research. According to literature data, anthocyanins are found in such natural objects as pansies, raspberries, strawberries, strawberries, cherries, plums, red cabbage, black grapes, beets, black chokeberries, currants, blueberries, cranberries and many others. Relevance of the topic lies in the fact that today more and more interest is in the properties of plant objects for their application and use in various fields of science, such as chemistry, biology and medicine. Objective: using research to prove the presence of natural indicators - anthocyanin pigments in plant objects and to study their properties. Research objectives: 1) Explore natural objects for the presence of indicators - anthocyanins; 2) To prove the indicator properties of plant pigments - anthocyanins; 3) Reveal the significance and biochemical role of natural objects containing anthocyanins. Research objects: strawberries, hawthorn, cherry, wild rose, bird cherry, beet roots, lungwort flowers. Research methods: experiment. 2. The main part. 2.1. Theoretical part 2.1.1. Chemical indicators. History of indicator formation Indicators(from Lat. Indicator - an indicator) - substances that allow you to monitor the composition of the environment or the course of a chemical reaction. Today, a large number of different indicators, both chemical and natural, are known in chemistry. Chemical indicators include such as acid-base, universal, redox, adsorption, fluorescent, complexometric and others. Also, indicators can be found among natural objects. The pigments of many plants can change color depending on the acidity of the cell sap. Consequently, pigments are indicators that can be used to study the acidity of other solutions. The common name for such plant pigments is flavonoids. This group includes the so-called anthocyanins, which have good indicator properties. The most famous plant acid-base indicator used in chemistry is litmus. It was already known in Ancient Egypt and Ancient Rome, where it was used as a purple paint substitute for expensive purple. Litmus was prepared from special types of lichens. The crushed lichens were moistened, and then ash and soda were added to this mixture. The prepared mixture was placed in wooden barrels, urine was added and kept for a long time. Gradually the solution became dark blue. It was evaporated and used in this form for dyeing fabrics. Later litmus was discovered in 1663. It was an aqueous solution of lichen growing on rocks in Scotland. The following historical fact is also known: “In the laboratory of the famous English scientist physicist and chemist Robert Boyle, as usual, hard work was in full swing: candles were burning, various substances were heated in retorts. The gardener entered Boyle's study and placed a basket of deep purple violets in the corner. At this time, Boyle was going to conduct an experiment on the production of sulfuric acid. Fascinated by the beauty and aroma of violets, the scientist, taking a bunch with him, went to the laboratory. The lab technician told Boyle that two bottles of hydrochloric acid were delivered from Amsterdam yesterday. Boyle wanted to look at the acid, and to help the technician pour the acid, he put the violets on the table. Then, before heading to the office, he took his bouquet and noticed that the violets were slightly smoking from the spray of acid on them. To rinse the flowers, he dipped them into a glass of water. After a while, he glanced at the glass with violets, and a miracle happened: the dark purple violets turned red. Naturally, the scientist began research. He found that other acids also stain violet petals red. He thought that if he prepared an infusion from the petals and added it to the solution under study, he would be able to find out if it was sour or not. Boyle began to prepare infusions from other plants: medicinal herbs, tree bark, plant roots, etc. However, the most interesting was the purple infusion obtained from litmus lichen. Acids changed its color to red, and alkalis to blue. Boyle ordered to soak paper with this infusion and then dry it. This is how the first litmus paper was created, which is available in any chemical laboratory. Thus, one of the first substances was discovered, which Boyle already then called “ indicator. " Robert Boyle prepared an aqueous solution of litmus lichen for his experiments. The bottle in which he kept the infusion was needed for hydrochloric acid. After pouring out the infusion, Boyle filled a bottle with acid and was surprised to find that the acid turned red. Intrigued by this phenomenon, Boyle added a few drops to an aqueous solution of sodium hydroxide for a test and found that in an alkaline medium the litmus turns blue. So the first indicator for the detection of acids and alkalis was discovered, named after the lichen by the litmus. Since then, this indicator has been one of the indispensable indicators in various research in the field of chemistry. " Acid-base indicators. Most often, acid-base indicators are used in laboratories. These include phenolphthalein, litmus, methyl orange, bromothymol blue, and others. Acid-base indicators are organic compounds that can change color in solution when acidity changes. They change color within fairly narrow pH ranges. There are many such indicators, and each of them has its own field of application. Such indicators are among the most stable and in demand in chemistry laboratories. 2.1.2 . Natural indicators. Characteristics and classification. Since ancient times, people have paid great attention to observing nature. And in our time, the teachings of many countries are increasingly turning to natural indicators. The pigments of many plants can change color depending on the acidity of the cell sap. Therefore, plant pigments are indicators that can be used to study the acidity of other solutions. The general name for natural pigments is flavonoids. This group includes carotenoids, xanthophylls, anthocyanins, respectively, determining the yellow, orange, red, blue, purple color of plants. Anthocyanins are natural pigments from the flavonoid group. A large number of objects are known to be rich in anthocyanins. These are raspberries, strawberries, strawberries, cherries, plums, red cabbage, black grapes, beets, blueberries, blueberries, cranberries and many others. Anthocyanins give the fruits purple, blue, brown, red or orange colors. This variety is due to the fact that the color changes depending on the balance of acids and alkalis. The structure of anthocyanins was established in 1913 by the German biochemist R. Willstatter. The first chemical synthesis was carried out in 1928 by the English chemist R. Robinson. The variety of colors is explained not only by the peculiarities of their structure, but also by the formation of complexes with ionic K (purple salt), Mg and Ca (blue salt), as well as adsorption on polysaccharides. The formation of anthocyanins is favored by low temperatures and intense lighting. Anthocyanins have good indicator properties: in a neutral medium they acquire a purple color, in an acidic medium - a red color, in an alkaline medium - a green-yellow color. Anthocyanins very often determine the color of petals, fruits and autumn leaves. They usually give purple, blue, brown, red color. This color often depends on the pH of the cell content, and therefore can change with ripening of fruits, flowering of flowers in processes accompanied by acidification of cell sap. Plants with a high concentration of anthocyanins are popular in landscape design. Many people believe that the color of autumn leaves (including red) is simply the result of the destruction of chlorophyll, which masked the already existing yellow, orange and red pigments (carotenoid, xanthophyll and anthocyanin, respectively). And if this is really the case for carotenoids and xanthophylls, then anthocyanins are not present in the leaves until the level of chlorophylls begins to decrease in the leaves. This is when plants begin to synthesize anthocyanins. Unfortunately, almost all natural indicators have a serious drawback: their decoctions quickly deteriorate - they turn sour or moldy. Another drawback is the too wide range of color change. In this case, it is difficult or impossible to distinguish, for example, a neutral medium from a weakly acidic or slightly alkaline from a strongly alkaline one. What is the biochemical role of indicators? Indicators allow you to quickly and accurately monitor the composition of liquid media, monitor changes in their composition or the course of a chemical reaction. As already mentioned, the common name for all natural pigments, natural indicators, is flavonoids. Flavonoids are heterocyclic compounds. Depending on the structure and oxidation state, they are divided into anthocyanins, catechins, flavonols, flavonones, carotenoids, xanthophylls, etc. They are found in plants in a free state and in the form of glycosides (with the exception of catechins). Anthocyanins are bioflavonoids that give the fruit purple, blue, brown, red color. Entering the human body with fruits and vegetables, anthocyanins exhibit an effect similar to vitamin P; they maintain a normal state of blood pressure and blood vessels, preventing internal hemorrhages. Anthocyanins are required by brain cells, improve memory. Anthocyanins are powerful antioxidants that are 50 times stronger than vitamin C. Many studies have confirmed the benefits of anthocyanins for vision. The highest concentration of anthocyanins is found in blueberries. Therefore, preparations containing blueberries are most in demand in medicine. Since anthocyanins have good indicator properties, they can be used as indicators for identifying acidic, alkaline or neutral environments, both in chemistry and in everyday life. 2.2. Research part. 2.2.1. Introduction. Strawberries, bird cherry, black currant, cherry, wild rose, red cabbage, blueberry and beetroot were selected as natural indicators. These are the natural objects that contain the highest concentration of anthocyanins. Therefore, we set ourselves the purpose of the research: by means of research to prove the presence of natural indicators - anthocyanins in plant objects and to study their properties. To achieve the goal of the work, the following tasks were set: 1) examine natural objects for the presence of indicators - anthocyanins; 2) prove the indicator properties of plant pigments - anthocyanins; 3) to reveal the significance and biochemical role of natural objects containing anthocyanins. 2.2.2 Research methodology. Knowing about the ability of anthocyanins to change their color in various environments, you can prove their presence or disprove. To do this, cut or rub the test material, then boil, as this leads to the destruction of cell membranes, and anthocyanins freely leave the cells, staining the water. The solutions are poured into a transparent bowl and ammonia or soda solution is added to one portion, and vinegar is poured into the other. If the color changes under their influence, then the products contain anthocyanins and they are especially useful. The extraction of anthocyanins from plant cells can also be achieved mechanically: grind the material in a mortar with sand, add about 10 ml of water and filter. 2.2.3 Research results. Study material Regular tea can be used at home as an indicator. Have you noticed that tea with lemon is much lighter than without lemon. In an acidic environment, it becomes discolored, and in an alkaline environment it becomes darker.
Grade 8 students, conducting research on primroses, discovered an interesting feature of the lungwort. Its stems developed even under the snow, and when the soil was exposed, already colored buds appear at the lungwort. The buds are pink and the blossoming flowers are painted in hot pink color. But several days pass, and the color of the flower changes: it turns purple, and then purple, then turns blue, and later sometimes turns blue and even turns white. The inflorescence of the lungwort is a multi-colored bunch. The uppermost, just blossoming flowers are pink, lower ones are purple and blue. Why does the color of the flower change? It depends on the presence of a special coloring agent in the petals of the flower - anthocyanin. This substance changes its color: turns pink from acid and turns blue from alkali. With the age of the flower, the composition of the cell sap in the petals of the lungwort changes: the sap initially sour then becomes alkaline. The color of anthocyanin also changes: it turns blue. Let's check these phenomena with the help of experiments. Conducted the following experiments with lungwort flowers: 1.The pink lungwort flower was dropped into the water and ammonia or soda solution was dropped there - the flower turns blue. Why? (Because the solution medium has become alkaline.) 2. They took a blue flower, put it in another glass of water and dropped vinegar essence into it - the blue flower will turn pink. Cause? (Wednesday turned sour.) 2.2. 4 . Conclusions of the study. According to the results of our study, the indicator properties of the objects under study were proved. Moreover, the following pattern is observed here - all these natural objects in an acidic environment are predominantly colored red, and in an alkaline environment - in green-yellow. And this proves that they do contain anthocyanins. This study showed us that in nature there are such plant objects that change their color depending on the acidity of the environment. Therefore, we can call them natural indicators.. 3. Conclusion. As a result of this research work, we have proved that among natural objects there are a large number of natural indicators that can be used and applied both in everyday life and in chemistry for various other studies. And also anthocyanins are often used in medicine due to their unique properties. Anthocyanins are of immense biochemical importance. Anthocyanins are powerful antioxidants that neutralize free radicals, which in turn have a detrimental effect on our body. Thus, anthocyanins are the guarantors of a long and healthy cell life, which means they extend our life as well. Many studies have confirmed the benefits of anthocyanins for vision. They also help lower blood sugar levels. This is especially true for those people who are sick with diabetes. To get all these benefits, scientists advise to eat only half a glass of blueberries a day - fresh or frozen. Therefore, preparations containing blueberries are most in demand in medicine. 4. Literature. 1. Vetchinsky K.M. Vegetable indicator), Moscow: Education, 2002, 256 p. 2. Vronsky V.A. Vegetable indicator. - SPb .: Parity, 2002 .-- 253p. 3. Galin G.A. Plants help geologists. - M .: Nauka, 1989 .-- 99p. 4. Zatser L.M. On the use of indicator plants in chemistry. - M .: Nauka, 2000 .-- 253p. 5. Leenson I.A. Entertaining chemistry: grades 8-11. - M .: Education, 2001 .-- 102s. 6. Sokolov V.A. Natural Dyes), Moscow: Enlightenment, 1997. 7. Magazine "Chemistry in School" No. 2, No. 8 - 2002.
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