Presentation on the topic of natural indicators. Presentation on the topic "indicators". Analysis of household products

Municipal educational institution "Bersenevskaya secondary school". Supervisor: ,

Chemical and natural indicators are of great importance, since it is very important to know the pH - the environment in any biological and chemical processes. For example, for plant growth, to obtain baking soda or detergent, a certain acidic or alkaline environment is required. In the body of animals and humans, blood and gastric juice have a constant pH, and when it changes, vital processes are disrupted. Research in the field of indicators helps regulate the pH value.

In chemical laboratories, including school ones, there are many different types and types of indicators. We all know litmus, methyl orange, phenolphthalein and others. In addition to chemical indicators, there are biological ones.

Target This research work is to learn how to prepare extracts of indicators from plants in our area and apply them in practice.

Job objectives:

1. Get acquainted with the history of the discovery of some acid-base indicators.

2. Consider the principle of biological indication using the examples of algae, mosses, lichens, higher plants and become familiar with the bioindicators of the hydrosphere, atmosphere, acidity and chemical composition of soils.

3. Study the method of preparing natural indicators.

4. Experimentally explore the possibility of using natural indicators to determine the environment of household solutions (soap, shampoo, washing powder, tea, soil extract.)

5. Improve experimental skills.

Objects of study:

1. Natural substances that can be used to prepare acid-base indicators: juices of brightly colored fruits and berries, cell juice of flower petals of various plants.

2. Solutions of substances that are used in everyday life (tea), soil extract from a school experimental site.

This research work examines the history of the discovery of some indicators, their classification, and considers the principle of biological indication using the examples of algae, mosses, lichens, and higher plants. In the process of work, natural indicators were prepared and the possibility of using natural indicators to determine the environment of some household solutions (soap, shampoo, washing powder, tea, soil extract.) was experimentally investigated.

As a result of the analysis of the obtained work results, the following conclusions were made:

Dishwashing detergents “Myth”, “Fairy”, “AOS”, “Pril” have an alkaline and slightly alkaline environment, so 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 ;

Dove soap and Children's shampoo have a neutral environment, so they can be used on delicate children's skin;

Clean Line soap should not be used by people with dry skin, since this type of soap, having an alkaline reaction, will dry out the skin;

The Lotus washing powder taken for research has pronounced basic properties, so you need to work with it carefully. It is better not to wash woolen and silk items in this powder.

The tea variety “May tea, fruit” has an acidic environment, so it should not be drunk by people with high stomach acidity.

The soil taken for research from the school experimental plot has acidic properties, so work should be done to lim it, since acidic soil adversely affects the development of plants.

As a result of research, we are convinced that natural indicators surround us everywhere and are always at hand. They determine both the pH environment of chemical and biological processes and the state of our planet as a whole.

The study of indicator plants is an interesting and useful topic. Moreover, expensive indicators cannot always be bought or ordered, but preparing them yourself is not at all difficult. Natural indicators from natural raw materials can be used in chemistry lessons in schools, if there is a problem of providing the school with chemical indicators, in classes of optional and elective courses.

Perhaps the development of research in this direction will help bring our planet out of the environmental crisis and to some extent improve its ecological condition.

The work took second place in the regional competition “First Steps”, third place in the republican competition “Intellectual Future of Mordovia”

The research work is posted on the school website: http://www. bersen. *****

“Boarding school for children with visual impairments”

IN THE WORLD

INDICATORS

	INTRODUCTION
	HISTORY OF THE DISCOVERY OF INDICATORS	4 - 5
	CHEMICAL INDICATORS	6 - 8
III.	NATURAL INDICATORS	9 - 10
	USING INDICATORS
	Biochemical role of indicators and application in medicine
	Application of natural indicators in the national economy
	Using 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 solution environment of some fermented milk products
	CONCLUSION
	LIST OF SOURCES USED

INTRODUCTION

Indicators are widely used in chemistry, including in school. Any schoolchild will tell you what phenolphthalein, litmus or methyl orange are. When getting acquainted with acids and bases, I learned that when one or another indicator is added to an acidic or alkaline environment, the solutions change color. Therefore, indicators are used to determine the reaction of the environment (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? Is it possible to prepare solutions of plant indicators yourself? Are homemade indicators suitable for use at home, for example, to determine the environment of food products or household chemicals in order to identify their negative effects on the skin of the hands? Think, relevance of the topic is that the properties of plant objects can be used for application in various fields of science, such as chemistry, for example.

Hypothesis: solutions of plant indicators can be prepared independently and used at home to determine the environment of certain drinks and detergent solutions.

Goal of the work: Study the effect of chemical and natural indicators in various environments.

Tasks:

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;

Investigate the effect of natural indicators in various environments (determine the environment of solutions of some food products, berry juices and solutions of dishwashing detergents).

I . HISTORY OF THE DISCOVERY OF INDICATORS

Substances that change their color depending on the environment were first discovered in the 17th century by the English chemist and physicist Robert Boyle. He conducted thousands of experiments. Here's one of them.

Candles were burning in the laboratory, something was boiling in the retorts, when the gardener came in at the wrong time. He brought a basket of violets. Boyle loved flowers very much, but the experiment had to begin. He took several flowers, smelled them and put them on the table. The experiment began, they opened the flask, and caustic steam poured out of it. When the experiment ended, Boyle accidentally looked at the flowers; they were smoking. To save the flowers, he put them in a glass of water. And - what miracles - the violets, their dark purple petals, turned red. Random experience? A chance find? Robert Boyle would not have been a real scientist if he had missed such an incident. The scientist ordered his assistant to prepare solutions, which were then poured into glasses and a flower was dropped into each. In some glasses, the flowers immediately began to turn red. Finally, the scientist realized that the color of violets depends on what substances are contained in the solution. Then Boyle became interested in what plants other than violets would show.

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 the flask with acid and was surprised to find that the acid turned red. Interested in this, Boyle added a few drops of litmus infusion to an aqueous solution of sodium hydroxide as a test and discovered that litmus turns blue in an alkaline environment.

Experiments followed one after another, cornflowers and other plants were tested, but still the best results were obtained from experiments with litmus lichen. So, in 1663, the first indicator for detecting acids and bases was discovered, named litmus after the lichen.

In 1667, Robert Boyle proposed soaking filter paper with a decoction of tropical lichen - litmus, as well as decoctions of violets and cornflowers. Robert Boyle called the dried and cut “cunning” pieces of paper indicators, which translated from Latin means “pointer”, since they point to the environment solution.

It was the indicators that helped the scientist discover a new acid - phosphoric acid, which he obtained by burning phosphorus and dissolving the resulting white product in water.

Litmus became the oldest acid-base indicator. It must be said that the coloring substance litmus itself was known in Ancient Egypt and Ancient Rome. It was extracted from certain types of lichens that grew on the rocks of Scotland and was used as a purple dye, but over time, the recipe for its preparation was lost.

In 1640, botanists described heliotrope, a fragrant plant with dark purple flowers, from which a coloring substance was also isolated. This dye, along with violet juice, also became widely used by chemists as an indicator, which was red in an acidic environment and blue in an alkaline environment.

Later, in the mid-19th century, chemists learned to artificially synthesize acid-base indicators. So in 1871, the German organic chemist Adolf von Bayer, a future Nobel Prize laureate, first synthesized phenolphthalein.

Today, several hundred artificially synthesized acid-base indicators are known.

II . CHEMICAL INDICATORS

The word "indicator"used in various fields of human activity - mechanics, mathematics, biology, ecology, economics, social sciences, 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 the state of an object in a form that is most convenient for direct human perception visually, acoustically, tactilely or in another easily interpretable way. We will only consider chemical indicators.

Chemical indicators- these are substances that change color, luminescence, or form a precipitate when the concentration of any component in the solution changes. They are of natural and chemical origin. Indicators are most often used to determine 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 environment). This happens because in acidic and alkaline environments, indicator molecules have different structures. An example is the well-known indicator phenolphthalein. In an acidic environment, this compound is in the form of undissociated molecules and the solution is colorless, and in an alkaline environment it is in the form of ions and the solution has a crimson color. Such indicators sharply change their color within a fairly narrow pH range.

Universal indicators are mixtures of several individual indicators, selected so that their solution alternately changes color, passing through all the colors of the rainbow when the acidity of the solution changes over a wide pH range.

pH is a hydrogen indicator. This concept was introduced by the Danish chemist Sørensen for an accurate numerical characteristic of the solution environment and proposed a mathematical expression for its definition:

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 occur 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 environment is neutral, at pH 7 it is alkaline. The medium 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, and glacial acetic acid. Its main components are: azolitmin (C 9 H 10 NO 5) and erythrolitmin (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 pharmacies 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 environment, and is colorless in neutral and acidic environments.

Methyl orange, C 14 H 14 N 3 O 3 SNa, is an orange crystalline powder, moderately soluble in water, insoluble in organic solvents. Methyl orange is truly orange in a neutral environment. In acids its color becomes pink-crimson, and in alkalis it turns yellow.

Depending on the acidity of the medium, the color and dye changes brilliant green(its alcohol solution is used as a disinfectant - brilliant green). In a strongly acidic environment its color is yellow, and in a strongly alkaline environment the solution becomes discolored.

In addition to acid-base indicators, other types of indicators are known: adsorption, complexometric , fluorescent, isotopic, redox and others.

universal indicator paper. It is based on a mixture of indicators that allows you to determine 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 you can quickly (with an accuracy of tenths of pH) determine the acidity of the aqueous solutions under study. For a more accurate determination, the color of the indicator paper obtained when applying a drop of solution is immediately compared with the 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, home-made indicators from natural raw materials can be successfully used to determine the solution environment.

The starting raw materials can be geranium flowers, peony or mallow petals, iris, dark tulips or pansies, as well as raspberries, blueberries, chokeberries, cherry, currant, grape juices, buckthorn and bird cherry fruits.

These natural indicators contain colored substances (pigments) that can change their color in response to a particular stimulus. And when they find themselves in an acidic or alkaline environment, they visually signal this.

These pigments are, first of all, anthocyanins. They are (predominantly) red in acidic conditions and blue or green in alkaline conditions. Example:


Alkali solution
Acid solution

It is anthocyanins that give the varied shades of pink, red, blue and purple to many flowers, fruits and autumn leaves. This color often depends on the pH of the cellular contents, and therefore can change when fruits ripen, flowers fade, and leaves wilt.

Anthocyanins are unstable compounds; plant cells usually contain several different anthocyanins, and their manifestation is related to the chemical composition of the soil and the age of the plant.

Regular tea is also an indicator. If you drop lemon juice into a glass of strong tea or dissolve a few crystals of citric acid, the tea will immediately become lighter. If you dissolve baking soda in tea, the solution will darken (of course, you should not drink such tea). Tea made from hibiscus flowers gives much brighter colors.

An indicator is also ordinary ink, which, under the influence of acid, changes color from violet to green, and again acquires a violet color when the acid is neutralized with alkali.

Beetroot juice in an acidic environment changes its ruby color to bright red, and in an alkaline environment it changes to yellow. Knowing the properties of beet juice, you can make the color of borscht bright. To do this, add a little table vinegar or citric acid to the borscht.

Here is a list of plants whose leaves or fruits can be used to prepare natural indicators.

Red grapes

Cherry, berry juice

Pink geranium, 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

Red peony, petals

Radish red
Rose, petals
Red beets, juice
Thyme or oregano - flowers
Tulip, petals
Blackcurrant juice
Violet, petals

While on vacation in the 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 parts of plants used as natural indicators must be stored in a dark container. Unfortunately, natural indicators have a serious drawback: their decoctions deteriorate quite quickly - they turn sour or mold. Therefore, chemical laboratories use synthetic indicators that sharply change their color within fairly narrow pH limits.

IV . USING INDICATORS

Indicators allow you to quickly and accurately control the composition of liquid media, monitor changes in their composition or the progress of a chemical reaction.

As already mentioned, plants contain a lot of natural pigments, natural indicators, most of which are anthocyanins.

Since anthocyanins have good indicator properties, they can be used as indicators to identify 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 national economy, in the food industry and in everyday life.

1. Biochemical role of indicators and application in medicine

Data from recent years indicate that plant dyes play a huge biochemical role, have a variety of medicinal 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.

By forming complexes with radioactive elements that have a detrimental effect on our body, anthocyanins contribute to their rapid removal from the body. Thus, anthocyanins are the guarantors of long and healthy cell life, and therefore prolong our life. They have a protective effect on blood vessels, reducing their fragility, and help lower blood sugar levels.

When entering the human body with fruits and vegetables, anthocyanins exhibit an effect similar to vitamin P; they maintain normal blood pressure and blood vessels, preventing internal hemorrhages. Anthocyanins are required by brain cells and improve memory.

Anthocyanins have unique properties - they suppress tumor growth. For example, recent studies have shown that consuming anthocyanins in food helps reduce the risk of esophageal and rectal cancer. Aqueous and acidified infusions prepared from plants containing anthocyanins destroyed dysentery and typhoid bacteria within a few hours. 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

In addition to medicine, anthocyanins are also used in other areas of the national economy. For example, in agriculture, to assess the chemical composition of the soil, the degree of its fertility, and during mineral exploration. By adding a handful of soil to the anthocyanin solution, one can draw a conclusion about its acidity, since on the same soil, depending on its acidity, one type of plant can produce a high yield, while others will be depressed.

“Or take at least the well-known potato. It has different colors of peel, eyes, sprouts and pulp. The difference in color of potatoes depends on the pigments it contains. Colored potato tubers, as a rule, are richer in substances necessary for our body. 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, it is possible to observe a change in the color of potato tubers depending on the use of mineral fertilizers and pesticides. When applying phosphorus fertilizers, potatoes turn white, potassium sulfate gives them 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 also have similar properties. This allows us 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. Moreover, this method of monitoring the state of the environment is simpler and more economical” (N.N. Tretyakov. Textbook on agronomy).

3. Use of indicators in everyday life

Plant indicators can also be used at home.

Indicators help determine the environment of solutions of various household chemicals and cosmetics and remove stains of plant origin.

Even housewives use indicators to ensure that the borscht is bright red - a little food acid - acetic or citric - is added to it before the end of cooking; the color changes right before your eyes.

It has long been fashionable to write invitations on flower petals; and they were written, depending on the flower and the desired color of the inscription, with a solution of acid or alkali, 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 convict unscrupulous traders who added wheat flour to sour cream “for thickness.” If you drop iodine tincture on a sample of such sour cream, the blue color will immediately reveal the trick.

In the past, 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.

1. Preparation of natural indicators

from plant 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 an extract of natural indicators can be prepared in different ways - by boiling in water or extracting with some 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.


cowberry		black currant

		turmeric, black tea

1. Manufacturing of indicators.

To prepare plant indicators, I took 50 g of raw materials, crushed them, poured 100 ml of water and boiled for 1-2 minutes. This leads to the destruction of cell membranes, and anthocyanins freely leave the cells, coloring the water. The resulting decoctions were cooled and filtered. In order to protect against spoilage, alcohol was added to the resulting filtrate in a ratio of 2:1.

2. Studying the action of indicators in various environments, compiling a table of color changes.

Having received the indicator solutions, I checked what color they had in different environments.

A few 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 performed better. Not all substances have pronounced indicator properties. Black tea only changes color in acidic conditions, while carrots and turmeric only change color in alkaline conditions. All research data are included in the table:

Object under study	Original color	Acid staining	Alkali staining
Lingonberries	raspberry
cranberries	raspberry
Black currant berries	raspberry
	burgundy	hot pink	yellow-green
	orange	light orange
			brown
Black tea	brown		dark brown

Here are my best indicators

2. Determination of the environment of some household chemicals using the obtained indicators

Target: Using the obtained indicators, examine cosmetic, hygiene and detergent products.

Equipment: samples of detergents and cosmetics and hygiene products; vegetable indicators (from lingonberries, cranberries, black currants and beets); test tubes

Progress of the experiment: 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 slightly alkaline
Shampoo-conditioner. Clean line		crimson			The solution medium is neutral
Ordinary soap	pale pink	pale pink		brown-green	The solution medium is slightly 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 protection of the skin.

In biology and chemistry classes, I learned that the outer surface of the epidermis is covered with a microscopically thin layer - the 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 makes up the acid mantle of the skin. Therefore, normal skin is acidic, with an average skin pH of 5.5.

When using alkaline detergents, we disrupt the normal acidic environment of the skin of our hands. To protect the skin of your hands from the negative effects of such products, you need to work with them only with gloves. It’s even better to use other means: for example, wash your hands with good toilet soap or gel, or baby soap, to which alkali-neutralizing substances have been added. They irritate the skin less.

The shampoo in my family is correct, the environment of its solution is close to the environment of the scalp - it is completely safe.

3. Determination of the environment of solutions of some

fermented milk products

I also checked the reaction of the fermented milk products available at our home. But since I ran out of solutions of natural indicators, I worked with a paper universal indicator. Having dipped the indicator strip into kefir and homemade yogurt, I noticed that the paper had turned pink. I have proven the presence of acid in these products.

These are lactic and other organic acids, which increase the secretion of gastric juice, improve the functioning of the intestines, and normalize its microflora. Scientists claim that fermented milk cultures are more easily absorbed by the body than natural milk and prevent the proliferation 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. achieved his main goal. I learned what groups indicators are divided into and how they behave in acidic, basic and alkaline environments. It turns out that indicators can be used for various purposes. For example, to remove a stain from berries, you first need to wash the item in an acidic environment, and only then with a regular detergent. And you can also use indicators to use them to determine the environment of detergents and select the most appropriate product.

After conducting a series of experiments, I became convinced that indicators are in fact substances that change color when the concentration of hydrogen ions in a solution changes, and I confirmed my hypothesis.

In the modern world, with a huge variety of chemicals, it is necessary to know the rules for the correct use of these substances. Do not neglect the instructions for use.

After conducting research, 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 find themselves. These are the so-called natural indicators, brightly colored flowers and fruits of plants;

Solutions of plant indicators can be used, for example, as acid-base indicators to determine the environment of solutions of hygiene detergents and the quality of products at home;

Homemade indicators from natural raw materials can be used in chemistry lessons in schools if there is a problem in providing the school with chemical reagents.

Unfortunately, almost all natural indicators have a serious drawback: their decoctions spoil quite quickly, so more stable alcohol solutions are often used. The upside 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 home and in the country. I also hope that my work will contribute to the development of curiosity and observation in children.

1. Plant indicators can also be used at home. Beetroot juice in an acidic environment changes its ruby color to bright red, and in an alkaline environment it changes to yellow. Knowing the properties of beet juice, you can make the color of borscht bright. To do this, add a little table vinegar or citric acid to the borscht.

2. Natural indicators can be used to determine the composition of drugs used for treatment. Many drugs are acids, salts and bases. By studying their properties, you can protect yourself. For example, aspirin (acetylsalicylic acid) and many vitamins cannot be taken on an empty stomach, since the acids they contain will damage the gastric mucosa.

3. The results of research work can be used to determine the environment of various solutions, for example, dairy products, broths, lemonade and others, as well as to determine the acidity of the soil, because depending on this, one type of plant can produce a high yield, while others will oppressed.

4. “Folk” method for determining soil acidity. Place 3-4 blackcurrant or cherry leaves in a glass bowl and pour a glass of boiling water over them. When the water has cooled, throw a lump of earth into it. If the water turns red, the soil is definitely acidic, if it turns blue, it is slightly acidic, and if it turns green, it is neutral.

5. Dishwashing detergents 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. (Teacher's manual) - M.: Education, 1977.

Gabrielyan O.S. Chemistry. 11th grade. Basic level: educational for educational institutions. - M.: Bustard. 2008.

Kremenchugskaya M. Chemistry. – M.: Philological Society “Slovo”, 1995.

Kreshkov A.P. Fundamentals of Analytical Chemistry, 3rd ed., book. 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 and practical journal “Chemistry for schoolchildren”, No. 4, 2007.

11. Nifantiev E.E. Extracurricular work in chemistry using chromatography. - M.: Education, 1982.

12. Savina L.A. I'm exploring the world. Children's encyclopedia. Chemistry. – M.: AST, 1996.

13. Stepin B.D., Alikberova L.Yu. Entertaining tasks and spectacular experiments in chemistry. – M.: Bustard, 2002.

14. Pilipenko A.T. Handbook of elementary chemistry. – Kiev. Naukova Duma. 1973.

15. Educational and methodological newspaper for chemistry teachers “First of September”, No. 22, 2007.

16. Khramov V.A. Analytical biochemistry. - Volgograd: Uchitel Publishing House, 2007.

17. Shtempler G.I. Chemistry at 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 Sergei,

head Zakharova L.Yu.

Purpose of the 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; 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;
investigate the effect of natural indicators in various environments.

From the history of the discovery...

Robert Boyle, English chemist

and physicist of the 17th century, first discovered

substances that change color

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- these are substances that change color, luminescence, or form a precipitate when the concentration of any component in the solution changes.

7 METHYLORANGE colorless red orange blue crimson pink yellow" width="640"

Name

indicator

Neutral environment

LITMUS

PHENOLPHTHALEIN

Sour

c reda

colorless

violet

Alkaline environment

METHYLORANGE

colorless

red

orange

blue

crimson

pink

yellow

Nowadays, chemists often use universal indicator paper

USING INDICATORS

Ecology

Food industry

Agriculture

NATURAL INDICATORS

Medicine

Household

Production of cosmetics

Medicine

Anthocyanins are powerful antioxidants, 50 times stronger than vitamin C:

remove radioactive substances, prolonging the life of cells;
good for vision;
required by brain cells
improve memory,
suppress tumor growth.

Agriculture

Studying

soil fertility

Analysis

environmental

questions

Analysis of household products

chemistry and cosmetics

Adding food

acid in borscht will turn it bright red

Tasks :
1. Obtain natural indicators from available natural objects.
2. Create a color change scale for each indicator.
Object of study : natural plants with indicator properties.
Subject of study: solutions of homemade plant indicators.
Research methods:
Study of popular science literature;
Obtaining indicator solutions 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

Original color

Lingonberries

raspberry

cranberries

Acid staining

Black currant berries

raspberry

pink

Alkali staining

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. Defining 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

Shampoo-conditioner.

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

The solution medium is neutral

The solution medium is slightly alkaline

Research funds

solutions have an alkaline reaction

The studied dairy products have an acidic solution reaction

Objects of research: 1. Natural substances that can be used to prepare acid-base indicators: juices of brightly colored fruits and berries, cell sap of flower petals of various plants, brightly colored skin of fruits and tree bark. 2. Solutions of substances that are used in everyday life

Project objectives: 2. Study the methodology for preparing natural indicators. 3. 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. Study the chemical basis of natural indicators. 1. Consider the history of the discovery of some acid-base indicators.

Indicators (from English indikate - indicate) are substances that change their color depending on the solution environment. The indicators most widely used in the chemical laboratory are Litmus 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 performed thousands of experiments. Here's one of them. Candles were burning in the laboratory, something was boiling in the retorts, when the gardener entered with a basket of violets. The experiment began, they opened the flask, and caustic steam poured out of it. Boyle looked at the flowers, they were smoking. To save the flowers, he put them in a glass of water. And the flower petals turned from dark purple to red. The scientist ordered his assistant to prepare solutions, which were then poured into glasses. The scientist realized that the color of violets depended on what solutions were in the glass. Then Boyle became interested in what not violets, but other plants would show. 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 violet paint - a substitute for expensive purple. Then the recipe for making litmus was lost. It was only at the beginning of the 14th century that violet dye, orseille, was rediscovered in Florence. It was prepared as follows: 1. The 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

A coloring substance similar to orseille was isolated in the 17th century from heliotrope, a fragrant garden plant with dark purple flowers. It was from this time, thanks to R. Boyle, that Orseil and heliotrope began to be used in chemical laboratories. And only in 1704 the German scientist M. Valentin called this paint litmus. Modern production of litmus 1. Lichens are crushed 2. Fermented in a solution of potash (potassium carbonate) and ammonia. 3. Add chalk and plaster.

Methodology for preparing homemade plant indicators To establish a method for preparing plant indicators, we studied and examined the juices of brightly colored fruits and berries, the cell juice of flower petals of various plants, such as chamomile, rose hips, calendula, beets, peony, blueberries, black currants, tea, decoction of oak bark, Brussels sprouts. The best results were obtained using the following plants: blueberries and currants. 1. Prepare a decoction from the juice of blueberries or black currants. 2. To 30 g of berries, add 1 tablespoon of hot water. 3.Bring the solution to a boil. 4. Cooled, stirred for 2-3 minutes, allowed the solution to settle for 1-2 minutes.

5.Filtered. For filtering, we used a funnel made from a plastic bottle and filter paper. 6.Cut filter paper (1 cm wide, 4 cm long). 7. Soak strips of filter paper with the prepared broth for 2 minutes. 8. Dry the strips, keeping them away from bright light. 9. Store the prepared indicator papers in a dark container.

Characteristics of plant indicators Plant (part of it) pH=1 (acidic environment) pH=7 (neutral environment) pH=13 (alkaline environment) Dark beans RedVioletYellow-green Grapes (skin) PinkLilacYellow-green Azalea (flowers) Purple-red PinkYellow Blueberries (berries) Red Blue Blackcurrants (berries) Red Blue

Home experiment (results of a study of household solutions) Test solution Color Medium 1. Soil extract Red Sour 2. Dobry juice, apple Red Sour 3. Kefir “House in the Village” Red Sour 4. Milk “House in the Village” Violet Neutral 5. Soap solution “Clean line, cosmetic soap” Blue Alkaline

Chemical basis 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 the 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 environment - into a quinoid compound (3), which has a blue color. Since all these processes are reversible, by changing the pH of the medium, color transitions can be observed many times.

Conclusions from the experiment 1. This type of tea has high acidity, so people with high stomach acidity should not drink it. 2. The shampoo under study has a neutral environment, so it can be used for delicate children's skin. 3. The type of soap under study should not be used by people with dry skin, because This type of soap, having an alkaline reaction, will dry out 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, so work should be carried out on its liming, because acidic soil adversely affects plant development.

Conclusions on the work 1. Chemistry is a science that is directly related to the practical activities of man; it is no coincidence that the epigraph to the project was taken from the words of M. V. Lomonsov “Chemistry stretches its hands far into human affairs.” 2. We examined the history of the discovery of some indicators and the chemical basis of pH indicators from plants. 3. We studied the method of preparing pH indicators from plants. 4. Using homemade indicators, we determined the environment of some household solutions.

Dear Guys! Thank you for your attention! We are once again convinced that at home we can prepare indicator papers and use them to determine the acidity of household solutions. Work on the project will continue next year

Karelian branch of the Municipal Educational Institution Ustinskaya Secondary School of the Morshansky District.

Natural indicators

(research work)

Performed 8th grade student

Melsitova Yulia.

Teacher:Polyakova E.N.

Geography and Biology teacher

2011

Content.

1.Introduction pp. 5 - 4

2. Main part pp. 5 – 14

2.1.Theoretical part pp. 5 – 10

2.2. research part pp. 10 - 14

3. Conclusion page 15

4. Literature p.16

Introduction.

Nature is an amazing creation of the Universe. The natural world is beautiful, mysterious and complex. This world is rich in diversity of fauna and flora. This work is devoted to the unique properties of plants that never cease to amaze humanity. We will delve into their inner world, establish their connection with such sciences as chemistry, biology and even medicine.

So let's start with the simplest thing.

The plant kingdom surprises us with its variety of color shades. The color palette is so diverse that it is impossible to say how many colors and their shades exist in the plant world. Thus, the question arises - what determines the color of certain plants? What is the structure of plants? What do they contain? And what are their properties? The further we dive 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 contents of each plant. More precisely, the so-called bioflavonoids are to blame. These are chemical natural compounds that give a certain color shade and properties to any plant. Therefore, there are many bioflavonoids. These include anthocyanins, xanthophylls, carotenoids, catechins, flavonols, flavones and others.

The benefits of many plants are undeniable. Since ancient times, people have used plants as medicines. Therefore, it is not without reason that traditional medicine arose, based on the unique and medicinal properties of plants.

Why did we choose this topic?

Firstly, we are interested in the properties of plant objects.

Secondly, what is their role in a science like chemistry?

What determines their indicator properties?

And thirdly, how can their properties be used for medical purposes.

Therefore, we will consider flavonoids such as anthocyanins. Since they are ideal candidates for our study. According to the literature, anthocyanins are contained in such natural objects as pansies, raspberries, strawberries, wild strawberries, cherries, plums, red cabbage, black grapes, beets, chokeberries, currants, blueberries, cranberries and many others.

Relevance of the topic is that today there is more and more interest in the properties of plant objects for their application and use in various fields of science, such as chemistry, biology and medicine.

Goal of the work: using research, prove the presence of natural indicators - anthocyanin pigments in plant objects and study their properties. Research objectives:

1) Examine natural objects for the presence of indicators - anthocyanins;

2) Prove the indicator properties of plant pigments - anthocyanins;

3) Identify the significance and biochemical role of natural objects containing anthocyanins.

Objects of study: strawberries, hawthorn fruits, cherries, rose hips, bird cherry, beet roots, lungwort flowers. Research methods: experiment.

2. Main part.

2.1. Theoretical part

2.1.1. Chemical indicators. History of the formation of indicators

Indicators(from Latin Indicator - pointer) - substances that allow you to monitor the composition of the environment or the progress of a chemical reaction. Today, a large number of different indicators, both chemical and natural, are known in chemistry.

Chemical indicators include acid-base, universal, redox, adsorption, fluorescent, complexometric and others.

Indicators can also be found among natural objects. The pigments of many plants can change color depending on the acidity of the cell sap. As a consequence, pigments are indicators that can be used to study the acidity of other solutions. The general name for such plant pigments is flavonoids. This group includes the so-called anthocyanins, which have good indicator properties.

The best known 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 violet 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 acquired a dark blue color. It was evaporated and in this form used for dyeing fabrics.

Litmus was later 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 physicist and chemist Robert Boyle, as usual, intense work was in full swing: candles were burning, various substances were heated in retorts. The gardener entered Boyle's office and placed a basket of dark purple violets in the corner. At this time, Boyle was going to conduct an experiment to produce sulfuric acid. Admired by the beauty and aroma of violets, the scientist, taking a bouquet with him, headed to the laboratory. The laboratory technician told Boyle that two bottles of hydrochloric acid had been delivered from Amsterdam yesterday. Boyle wanted to look at this acid and, to help the laboratory assistant pour the acid, he put the violets on the table. Then, before heading into the office, he took his bouquet and noticed that the violets were slightly smoking from the splash of acid that had fallen on them. To wash the flowers, he put them in 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 discovered that other acids also turn violet petals red. He thought that if he prepared an infusion from the petals and added it to the test solution, he could find out whether it was sour or not. Boyle began preparing 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 the paper to be soaked in this infusion and then dried. 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 even 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 the flask with acid and was surprised to find that the acid turned red. Interested in this phenomenon, Boyle added a few drops to an aqueous solution of sodium hydroxide as a test and discovered that litmus turns blue in an alkaline medium. Thus, the first indicator for detecting acids and alkalis was discovered, named litmus after the lichen. Since then, this indicator has been one of the indispensable indicators in various studies in the field of chemistry.”

Acid-base indicators.

Acid-base indicators are most often used in laboratories. These include phenolphthalein, litmus, methyl orange, bromothymol blue and others.

Acid-base indicators are organic compounds that can change color in a solution when the acidity changes. They change color within fairly narrow pH limits. There are many such indicators, and each of them has its own area 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 teaching of many countries has increasingly begun to turn 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, and anthocyanins, which respectively determine the yellow, orange, red, blue, and violet color of plants.

Anthocyanins are natural pigments from the flavonoid group.

A large number of objects rich in anthocyanins are known. These are raspberries, strawberries, wild strawberries, cherries, plums, red cabbage, black grapes, beets, blueberries, blueberries, cranberries and many others.

Anthocyanins give purple, blue, brown, red or orange colors to fruits. This diversity is explained by the fact that color changes depending on the balance of acids and alkalis.

The structure of anthocyanins was established in 1913 by the German biochemist R. Willstetter. 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 temperature and intense lighting.

Anthocyanins have good indicator properties: in a neutral environment they acquire a purple color, in an acidic environment - red, in an alkaline environment - green-yellow.

Anthocyanins very often determine the color of petals, fruits and autumn leaves. They usually give purple, blue, brown, and red colors. This color often depends on the pH of the cellular contents, and therefore can change when fruits ripen and flowers fade in processes accompanied by acidification of cell sap.

Plants with high concentrations of anthocyanins are popular in landscape design. Many believe that fall leaf color (including red) is simply the result of the breakdown of chlorophyll, which masked the yellow, orange, and red pigments (carotenoid, xanthophyll, and anthocyanin, respectively) that were already present. And if this is true for carotenoids and xanthophylls, then anthocyanins are not present in leaves until chlorophyll levels in the leaves begin to decrease. This is when plants begin to synthesize anthocyanins. Unfortunately, almost all natural indicators have a serious drawback: their decoctions deteriorate quite quickly - they turn sour or mold. Another drawback is that the color change interval is too wide. In this case, it is difficult or impossible to distinguish, for example, a neutral medium from a weakly acidic one or a weakly alkaline from a strongly alkaline one.

What is the biochemical role of indicators?

Indicators allow you to quickly and accurately control the composition of liquid media, monitor changes in their composition or the progress of a chemical reaction.

As already mentioned, the common name for all natural pigments and natural indicators is flavonoids.

Flavonoids are heterocyclic compounds. Depending on the structure and degree of oxidation, 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 fruits their purple, blue, brown, and red colors.

Since anthocyanins have good indicator properties, they can be used as indicators to identify acidic, alkaline or neutral environments, both in chemistry and in everyday life.

2.2. Research part.

2.2.1. Introduction.

Strawberries, bird cherry fruits, black currants, cherries, rose hips, red cabbage, blueberries and table beets were selected as natural indicators. These are those natural objects that contain the highest concentration of anthocyanins. Therefore, we set ourselves

purpose of the study: with the help of research, prove the presence of natural indicators - anthocyanins in plant objects and 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) identify 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 different environments,

their presence can be proven or disproved. To do this, it is necessary to cut or rub the material under study, then boil it, as this leads to the destruction of cell membranes, and anthocyanins freely leave the cells, coloring the water. The solutions are poured into transparent containers 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.

Anthocyanins can also be extracted from plant cells mechanically: grind the material in a mortar and sand, add about 10 ml of water and filter.

2.2.3 Research results.

Material under study

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.

tea neutral environment tea in acidic and alkaline environment

8th grade students, while conducting research on primroses, discovered an interesting feature of the lungwort. Its stems developed while still under the snow, and when the soil was exposed, the lungwort appears with already colored buds.

The buds are pink and the blooming flowers are bright pink. But several days pass, and the color of the flower changes: it becomes purple, and then violet, then turns blue, and later sometimes turns blue and even white. The lungwort inflorescence is a multi-colored bouquet.

The topmost, newly bloomed flowers are pink, the lower ones are purple and blue.

Why does the color of the flower change?

This depends on the presence of a special coloring substance, anthocyanin, in the petals of the flower. This substance changes its color: it turns pink from acid and blue from alkali. As the flower ages, the composition of the cell sap in the petals of the lungwort changes: the sap, which is initially acidic, then becomes alkaline. The color of anthocyanin also changes: it turns blue. Let's check these phenomena with the help of experiments.

We conducted the following experiments with lungwort flowers:

1. Dip a pink lungwort flower into water and drop ammonia or soda solution into it - the flower turns blue. Why? (Because the solution environment has become alkaline.)

2.Take a blue flower, put it in another glass of water and drop vinegar essence into it - the blue flower will turn pink. Cause?

(the environment has become acidic.)

2.2. 4 . Conclusions of the study.

Based on the results of our study, the indicator properties of the studied objects were proven. Moreover, the following pattern is observed here - all these natural objects are predominantly colored red in an acidic environment, and green-yellow in an alkaline environment. And this proves that they do indeed contain anthocyanins. This study showed us that in nature there are 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 proven 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 other various studies.

Anthocyanins are also often used in medicine due to

their unique properties. Anthocyanins are of great 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 long and healthy cell life, and therefore prolong our life. 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 have diabetes. To get all these benefits, scientists recommend eating just half a cup of blueberries—fresh or frozen—a day. Therefore, preparations containing blueberries are most in demand in medicine.

4. Literature.

1. Vetchinsky K.M. Plant indicator. M.: Education, 2002. – 256 p.

2. Vronsky V.A. Plant indicator. - St. Petersburg: Parity, 2002. – 253 p.

3. Galin G.A. Plants help geologists. – M.: Nauka, 1989. - 99 p.

4. Zatser L.M. On the issue of using indicator plants in chemistry. – M.: Nauka, 2000. – 253 p.

5. Leenson I.A. Entertaining chemistry: grades 8-11. - M.: Education, 2001. – 102 p.

6. Sokolov V.A. Natural dyes. M.: Education, 1997.

7. Magazine “Chemistry at school” No. 2, No. 8 – 2002.

Municipal state educational institution

"Secondary school No. 17"

Pallasovki

Chemistry Research Project:

"Indicators around us"

Performed

Iskalieva Diana,

student of 8th grade "B"

Head – Baryshnikova M.V.,

chemistry teacher

Pallasovka, 2018

Content

INTRODUCTION

HISTORY OF THE DISCOVERY OF INDICATORS

II.

CHEMICAL INDICATORS

5 - 6

III.

USING INDICATORS

IV.

PRACTICAL PART

CONCLUSION

LIST OF SOURCES USED

INTRODUCTION

I first became acquainted with chemical substances in the 8th grade, when I began studying a chemistry course. I was amazed by the variety of substances in the modern world. I wondered how you can distinguish between substances, since some of them are visually identical? Recently we got acquainted with the classes of inorganic substances and their individual representatives, and learned some of their properties. During laboratory work, I found out that most solutions are colorless. How to distinguish between solutions? What can serve as a pointer in the endless world of chemicals? It turns out that there are such pointers in chemistry - these are indicators.Any schoolchild will tell you what phenolphthalein, litmus or methyl orange are.Therefore, the topic of my project is “Indicators around us.”

Objective of the project : Study the effect of chemical indicators in various environments.

Project objectives:

study literary sources on the topic;

consider three main types of indicators and their classification;

become familiar with their opening and functions;

study the effect of chemical indicators in various solution environments;

carry out practical work using three types of indicators.

I . HISTORY OF THE DISCOVERY OF INDICATORS

For the first time, substances that change their color depending on the environment were discovered inXVIIcentury English chemist and physicist Robert Boyle. He conducted thousands of experiments.Here's one of them.

In 1667, Robert Boyle proposed soaking filter paper with a decoction of tropical lichen - litmus, as well as decoctions of violets and cornflowers. Dried and chopped "tricky"Robert Boyle called the pieces of paper indicators, which translated from Latin means “pointer”, since they point to the solution environment.

In 1640, botanists described heliotrope, a fragrant plant with dark purple flowers, from which a coloring substance was also isolated. This dye became widely used by chemists as an indicator, which was red in an acidic environment and blue in an alkaline environment.

Later, in the middleXIXcenturies, chemists learned to artificially synthesize acid-base indicators. So in 1871, the German organic chemist Adolf von Bayer, a future Nobel Prize laureate, first synthesized phenolphthalein.

Today, several hundred artificially synthesized acid-base indicators are known.

II . CHEMICAL INDICATORS

The word "indicator"used in various fields of human activity - mechanics, mathematics, biology, ecology, economics, social sciences, social sciences and others.

Indicator(from Insk indicator - pointer) is a device, device, information system, substance or object that displays changes in any parameter of a controlled process or the state of an object in a form that is most convenient for direct human perception visually, acoustically, tactilely or in another easily interpretable way. We will only consider chemical indicators.

Chemical indicators - these are substances that change color, luminescence, or form a precipitate when the concentration of any component in the solution changes. They are of natural and chemical origin. Indicators are most often used to determine 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 most common indicators are litmus, phenolphthalein and methyl orange.

The very first acid-base indicator appearedlitmus . In fact, natural litmus is a complex mixture.This is a black powder, soluble in water, 95% alcohol, acetone, and glacial acetic acid.

The color of litmus in different environments changes as follows:

Acid

Alkali

Neutral

Wednesday

red

blue

violet

Phenolphthalein WITH 20 N 14 ABOUT 4 (sold in pharmacies under the name "purgen") - 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 environment, and is colorless in neutral and acidic environments.

Acid

Alkali

Neutral

Wednesday

colorless

crimson

colorless

Methyl orange , C 14 H 14 N 3 O 3 SNa, - orange crystalline powder, moderately soluble in water, insoluble in organic solvents. MEthyl orange is truly orange in a neutral environment. In acids its color becomes pink-crimson, and in alkalis it turns yellow.

Acid

Alkali

Neutral

Wednesday

pink

yellow

orange

III . USING INDICATORS

Indicators allow you to quickly and accurately control the composition of liquid media, monitor changes in their composition or the progress of a chemical reaction.

As already mentioned, plants contain a lot of natural pigments, natural indicators, most of which are anthocyanins.

Natural indicators are used in many areas of human activity: in medicine and ecology, in agriculture and national economy, in the food industry and in everyday life.

Anthocyanins are also used in cosmetics, because have a stabilizing effect and are collagens and in the food industry in the form of additive E163 as natural dyes. They are used in the production of confectionery, drinks, yoghurts and other food products. In addition to medicine, indicators are also used in agriculture, for example, to assess the chemical composition of the soil, the degree of its fertility, and during mineral exploration.

Plant indicators can also be used at home.

Indicators help determine the environment of solutions of various household chemicals and cosmetics and remove stains of plant origin.

Even housewives use indicators to ensure that the borscht is bright red - a little food acid - acetic or citric - is added to it before the end of cooking; the color changes right before your eyes.

In the past, 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.

IV . PRACTICAL PART

Action of chemical indicators in various environments

During laboratory research, I received indicator solutions and worked with them.

A few drops of each sample were added to solutions of water (neutral medium), hydrochloric acidHCl(acidic environment) and sodium hydroxideNaOH(alkaline environment).

Conclusion. All indicators changed their color in acidic and alkaline environments.

CONCLUSION

From literary and Internet sources, I learned about the actions of chemical indicators in various environments, i.e. achieved its main goal. I learned what groups indicators are divided into and how they behave in acidic, basic and alkaline environments. It turns out that indicators can be used for various purposes.

After conducting a series of experiments, I became convinced that indicators are actually substances that change color when the concentration of hydrogen ions in a solution changes.

In the modern world, with a huge variety of chemicals, it is necessary to know the rules for the correct use of these substances. Do not neglect the instructions for use.

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. (Teacher's manual) - M.: Education, 1977.

Gabrielyan O.S. Chemistry. 8th grade. Basic level: educational for educational institutions. - M.: Bustard. 2008.

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."

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