slide 3

• Object of study:
• Subject of study: solutions of plant indicators.
• Hypothesis:

slide 4

From the history of indicators

• 1640 - heliotrope
• 1663 litmus by Robert Boyle
• 1871 - synthesis of phenolphthalein Adolf von Bayer

slide 5

natural indicators

• raspberries
• mallow petals
• strawberries
• Black chokeberry berries
• Buckthorn bark
• red cabbage

slide 6

Method for manufacturing indicators

• To prepare vegetable indicators, it is necessary to take 50 g of raw materials, grind, pour 200 ml of water and boil for 1-2 minutes. The resulting broths cool and filter. In order to protect against spoilage, it is necessary to add alcohol to the resulting filtrate in a ratio of 2:1.

Slide 7

• Changing the color of natural indicators

Slide 8

Medium reaction of detergent solutions

• vegetable indicator
  • Red cabbage decoction
  • Red cabbage decoction
  • Strawberry decoction
  • A decoction of chokeberry berries
• Color indicator
  • pale green
  • Green
  • pale yellow
  • pale pink
• Solution medium
  • slightly alkaline
  • alkaline
  • slightly alkaline
  • subacid

Slide 9

• many natural plants have the properties of acid-base indicators;
• natural plants can be used to make plant indicator solutions;
• plant indicator solutions can be used as acid-base indicators both in chemistry lessons and at home;
• detergents for dishes "Myth", "Fairy", "AOS" have an alkaline and slightly 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;
• home-made indicators from natural raw materials can be used in chemistry lessons in rural schools if there is a problem in providing the school with chemical indicators.

Slide 10

Thank you for your attention!

View all slides

Abstract

�PAGE � �PAGE �7�

In the world of indicators

Salakhova Gulina Faritovna

Introduction page 3

From the history of indicators page 4

Natural indicators page 6

Conclusion page 9

References page 10

Appendix pages 11-12

Introduction

Objective: preparation of solutions of plant indicators from natural raw materials and determination of the environment of solutions of detergents for dishes with their help.

tasks:

Object of study: natural plants with indicator properties.

Subject of study

Hypothesis: vegetable indicator solutions can be prepared independently and used at home to determine the environment of dish detergent solutions.

From the history of indicators

Classification of indicators

indicators called adsorption.

fluorescent indicators

natural indicators

Conclusion

Bibliography

Internet resources.

Application

Mallow flower Buckthorn

Chokeberry Raspberry

Strawberries Red cabbage

�PAGE � �PAGE �7�

In the world of indicators

Chemistry teacher, Satlamyshev secondary school

Salakhova Gulina Faritovna

Introduction page 3

From the history of indicators page 4

Classification of indicators page 5

Natural indicators page 6

Method of manufacturing indicators from natural raw materials p. 7

Determining the environment of dishwashing detergents using

plant indicators page 8

Conclusion page 9

References page 10

Appendix pages 11-12

Introduction

Indicators are organic and inorganic 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 will tell you in a visual form whether the chemical reaction has gone to the end or not, whether one reagent has been added to another or more needs to be added. (5)

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 medium changes.

I was interested in the question: what plants can be used as indicators? Is it possible to prepare solutions of vegetable indicators on my own? Are homemade indicators suitable for use at home, for example, to determine the environment of dishwashing detergents in order to identify their negative effect on the skin of the hands?

Objective: preparation of solutions of plant indicators from natural raw materials and determination of the environment of solutions of detergents for dishes with their help.

To achieve this goal, it is necessary to solve the following tasks:

To study literary sources on the topic;

Consider the classification of indicators;

Prepare indicator solutions from natural raw materials;

Conduct a study to determine the environment of dish detergent solutions.

Object of study: natural plants with indicator properties.

Subject of study: solutions of plant indicators.

Hypothesis: vegetable indicator solutions can be prepared independently and used at home to determine the environment of dish detergent solutions.

From the history of indicators

The history of indicators begins in the 17th century. As early as 1640, botanists described heliotrope, a fragrant plant with dark purple flowers, from which a dye was isolated. This dye, along with the juice of violets, has become widely used by chemists as an indicator. This can be read in the writings of the famous 17th century physicist and chemist 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. Having poured out the infusion, Boyle filled the flask with acid and was surprised to find that the acid turned red. Intrigued by this, Boyle added a few drops of litmus infusion to an aqueous solution of sodium hydroxide for testing and found that litmus turns blue in an alkaline environment. Thus, the first indicator for the detection of acids and bases was discovered, named after the lichen litmus. (one)

Phenolphthalein, which is used in the form of an alcoholic solution, acquires a crimson color in an alkaline environment, and is colorless in a neutral and acidic environment. The synthesis of phenolphthalein was first carried out in 1871 by the German chemist Adolf von Bayer, the future Nobel Prize winner. (5)

As for the methyl orange indicator, it is indeed orange in a neutral environment. In acids, its color becomes pink-crimson, and in alkalis - yellow.

Currently, chemists often use indicator paper impregnated with a mixture of different indicators - a universal indicator.

Classification of indicators

One of the most common - acid-base indicators, which change color depending on the acidity of the solution. This happens because in an acidic and alkaline environment, the indicator molecules have a different structure. 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, in the form of ions, and the solution has a crimson color.

In addition to acid-base indicators, other types of indicators are also used.

Redox indicators change their color depending on whether an oxidizing or reducing agent is present 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 purple, while the reduced form is colorless.(2)

Widespread complexometric indicators- substances that form colored complex compounds with metal ions.

Some substances are adsorbed on the surface of the sediment, changing its color; such indicators called adsorption.

When determining the environment of cloudy or colored solutions, in which it is almost impossible to notice a change in the color of conventional acid-base indicators, use fluorescent indicators. They glow (fluoresce) in different colors depending on the pH of the solution. It is important that the glow of the indicator does not depend on the transparency and intrinsic color of the solution.(5)

natural indicators

If there are no real chemical indicators, then self-made indicators from natural raw materials can be successfully used to determine the environment of solutions.

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 can serve as feedstock.

These natural indicators contain colored substances that can change their color in response to a particular impact. And, getting into an acidic or alkaline environment, they clearly signal this. (6)

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.

Method for manufacturing indicators from natural raw materials

For research work, I used dried mallow petals, raspberries, chokeberries, strawberries, buckthorn bark, red cabbage.

To prepare plant indicators, I took 50 g of raw materials, chopped them, poured 200 ml of water and boiled for 1-2 minutes. The resulting broths were cooled and filtered. In order to prevent spoilage, alcohol was added to the resulting filtrate in a ratio of 2: 1. (8)

Having thus obtained solutions of indicators, I checked what color they have in different environments.

I took a few drops of a homemade indicator with a pipette and added them alternately to acidic or alkaline solutions. The results of all these experiments were recorded in a table.

Table 1. Color change of natural indicators in various media.

Determination of the environment of dish detergent solutions using vegetable indicators

In biology class, 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 makes up the acid mantle of the skin. Therefore, normal skin is acidic, with a skin pH of 5.5 on average. (2)

When using detergents for dishes that have an alkaline environment, we violate the normal acidic environment of the skin of the hands.

To protect the skin of the hands from the negative effects of dishwashing detergents, they must 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 various dishwashing detergents have.

Table 2. Environmental reaction of dish detergent solutions.

Conclusion

After doing research, I came to the following conclusions:

Many natural plants have the properties of acid-base indicators that can change their color depending on the environment in which they fall;

For the manufacture of plant indicator solutions, the following natural raw materials can be used: raspberries, strawberries, chokeberries, buckthorn bark, mallow petals, red cabbage;

Vegetable indicator solutions can be used as acid-base indicators to determine the environment of household dish detergent solutions;

Detergents for dishes "Myth", "Fairy", "AOS" have an alkaline and slightly 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;

Self-made indicators from natural raw materials can be used in chemistry lessons in rural schools if there is a problem of providing the school with chemical indicators.

Bibliography

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.

Oganesyan E.T. A guide to chemistry for those entering universities. – M.: graduate School, 1998.

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

New encyclopedic dictionary. – M.: Great Russian Encyclopedia. Rinol Classic, 2000.

Encyclopedic Dictionary of a Young Chemist. - M .: Pedagogy, 1982.

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

Internet resources.

Application

Plants are natural indicators

Mallow flower Buckthorn

Chokeberry Raspberry

MKOU Marshanskaya secondary school

Research work in chemistry

"Indicators in our lives".

The work was done by 8th grade students.

Sidorova Larisa

Kuryshko Anastasia

Burmatova Svetlana

Leader: Sinitsina Margarita

Anatolyevna - chemistry teacher

2016

Introduction

History of opening indicators

Classification of indicators.

natural indicators

Experimental part.

Conclusion.

Bibliography.

1. Introduction

In nature, we encounter various substances that surround us. This year we started 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 are 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 such indicators as litmus, phenolphthalein and methyl orange.

Indicators (from English indicate-indicate) are substances that change their color depending on the medium of the solution. With the help of indicators, you can determine the environment of the solution

We decided to find out whether it is possible to use the natural materials that are at home as indicators.

Objective:

To study the concept of indicators;

Familiarize yourself with their opening and their functions;

Learn to identify indicators from natural objects;

Investigate the effect of natural indicators in various environments;

Research methods :

The study of popular science literature;

Obtaining indicator solutions 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 conducting another study, a 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 experimented with solutions, adding violets each time and observing what happened to the flowers. In some glasses, the flowers immediately began to turn red. The scientist realized that the color of violets depends on what solution is in the glass, what substances are contained in the solution. The best results were given by experiments with litmus lichen. Boyle dipped ordinary paper strips into the infusion of litmus lichen. I waited until they were saturated with infusion, and then dried them. These cunning pieces of paper Robert Boyle called indicators, which in Latin means "pointer", as they indicate the medium of the solution. It was the indicators that helped the scientist to 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 is 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 called "purgen") - white or white with a slightly yellowish tint fine crystalline powder. Soluble in 95% alcohol, practically insoluble in water. Colorless phenolphthalein is colorless in an acidic and neutral environment, and in an alkaline environment it turns crimson. Therefore, phenolphthalein is used to determine the alkaline environment.

methyl orange - orange crystalline powder. Sparingly soluble in water, freely soluble in hot water, practically insoluble in organic solvents. The color of the solution changes from red to yellow.

Lakmoid (litmus) - black powder. Soluble in water, 95% alcohol, acetone, glacial acetic acid. The color of the solution changes 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 method of application is the use of strips of paper impregnated with an indicator solution or a mixture of indicators and dried at room temperature. Such strips are produced in a wide variety of versions - with or without a color scale printed on them - a color standard.

3. Natural indicators

Acid-base indicators are not only chemical. They are all around us, but usually we do not think about it. These are vegetable indicators that can be used in everyday life. For example, table beet juice in an acidic environment changes its ruby ​​color to bright red, and in an alkaline environment it changes to yellow. Knowing the property of beetroot juice, you can make the color of borscht bright. To do this, add a little table vinegar or citric acid to the borscht. If you drop lemon juice or dissolve a few crystals of citric acid into a glass of strong tea, 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 parts of plants are most often used as natural indicators. Such solutions must be stored in a dark container. Unfortunately, natural indicators have a serious drawback: their decoctions deteriorate rather quickly - turn sour or moldy (alcoholic solutions are more stable). In this case, it is difficult or impossible to distinguish, for example, a neutral medium from a slightly acidic one or a slightly alkaline one from a strongly alkaline one. Therefore, in chemical laboratories, synthetic indicators are used that sharply change their color within fairly narrow pH limits.

experimental part

What indicators can be used at home? To answer this question, we examined solutions of the 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 (pink and white flowers), dandelion, pansies, blackcurrant and raspberry (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: some leaves, flowers or fruits were ground in a mortar, then a little water was added. 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 environment. The results of the obtained studies were entered in the table

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