Start in science. Research project "in the world of indicators" Indicators in nature research work
Karachay-Cherkess Republic
MKOU "Secondary School a. Small Zelenchuk named after the Hero of the Soviet Union
Umar Khabekova »
Khabezsky municipal district
in chemistry on the topic:
"Indicators in our house."
Work completed:
Kalmykova Sataney
8th grade student
Supervisor:
chemistry teacher of the highest qualification category
Okhtova Elena Ramazanovna
2015
Content
Introduction……………………………………………………………………..……3
Theoretical part.
1 .1.Natural dyes …………………………………………………………………………………………………………………………………………………………………………………………………………………………………4
1 .2.The concept of indicators………………………………………………………..6
1.3. Classification of school indicators and how to use them..7
1.4. Hydrogen index……………………………………………………..8
Practical part.
2.1 Receipt natural indicators……………………………………...…9
2.2. Study of the medium of solutions with plant indicators………….10
Chemical experiments with food………………………….10
Chemical experiments with detergents……………………...…11
Conclusions…………………………………………………………………………...13
Conclusion………………………………………………………………………….13
References……………………………………………………………....14
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.
At chemistry lessons, the teacher told us about indicators: indicators such 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.
Relevance and novelty themes is that “as a result of the uncontrolled scientific technical progress on the planet, in general, and in Russia, in particular, the ecological situation is deteriorating from year to year, both in cities and in rural areas. Food additives appear on sale - dyes, thousands of drugs made from new polymers that are qualitatively different from natural ones. The food industry has become widespread based on the technology of deep chemical processing of natural products, as well as the production of genetically modified cereals, vegetables and fruits. As a result of this, we already now live in a largely artificial, "toxic" ecosystem (atmosphere, hydrosphere, lithosphere, biosphere). This ecosystem is significantly different for the worse from the one in which our ancestors lived.”
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 solutions of indicators and working with them.
Hypothesis: Can plants or vegetables of the area serve as bioindicators of acidity as environmentally safe for human health.
Tasks:
prepare solutions of indicators that would indicate the presence of an acid or base;
Check the acidity of the environment of soap, tea and food.
Subject of study: grape juice, beets, tea, detergents and food.
I . theoretical part.
1.1. natural dyes.
People obtained the first paints from flowers, leaves, stems and roots of plants. For a long time, Russian peasants used vegetable dyes, they dyed wool and linen fabrics in various colors. To obtain the dye, crushed parts of plants were usually boiled in water and the resulting solution was evaporated to a thick or solid precipitate. Then the fabrics were boiled in a dye solution, adding soda and vinegar for color strength.
The main component of the paint is the dye.Dye - This is a coloring chemical compound that gives the material a certain color.
The use of natural dyes has been known since 3000 BC. In the old days, organic dyes were extracted exclusively from animals and plants. For example, a violet-blue dye was isolated from the leaves of the tropical plant Indigofera growing in India.indigo . From the leaves of the genus Lavsonia (Henna) of the Loosestrife family, they are still isolatedhenna- red-orange dye, green henna is obtained from dried and rubbed viburnum leaves, which are widely used to strengthen and color hair. The Chinese have been using dye to dye silk, paper, wood, and food since ancient times.curcumin, contained in the rhizomes and stems of plants of the genus turmeric (curry). In Russia, for a long time, for dyeing fabrics, eggs for Easter, they used onion peel, leafy bark, birch brooms, sleep-grass (snowdrop); marigold flowers, juniper berries and other dyes isolated from plants growing in our climatic conditions.
The color of paints is mainly determined by the pigments included in their composition (from the Latin “pigmentum” - paints). Pigments are different: natural and synthetic, organic and inorganic nature, chromatic (from the Greek "croma" - "color") and achromatic. Achromatic pigments determine the white and black colors, as well as all the gray colors lying between them.
Pigments , in biology - the colored substances of the tissues of organisms involved in their life. Determine the color of organisms in plants they participate in photosynthesis (chlorophylls, carotenoids), in animals - in tissue respiration (hemoglobins), in visual processes (visual purple), protect the body from the harmful effects of ultraviolet rays (in plants - carotenoids, flavonoids, in animals - mainly melanins ). Some pigments are used in the food industry and medicine.
Pigments (from Latin pigmentum - paint), in chemistry - colored chemical compounds used in the form of fine powders for dyeing plastics, rubber, chemical fibers, and making paints. They are divided into organic and inorganic. Of the organic pigments, the most important are azo pigments, phthalocyanine and polycyclic pigments. Pigments also include organic varnishes.
Inorganic pigments are divided into natural and artificial (soot, ultramarine, white, etc.).Mineral paints (natural), natural pigments (ochre, yellow red lead, cinnabar, mummy, chalk, lapis lazuli, etc.) used for coloring materials.
Vegetable paints are not stored for a long time, like aniline paints, so they are not used in industry. Dyes are used not only for dyeing fabrics, but also for the preparation of drinks, creams, caramel. Many vegetables owe their color to pigments - carotenoids. Numerous representatives of the carotene family differ from each other in the composition and structure of molecules, which affects the shades of their color, but they all have one common property - solubility in fats.
With the development of chemistry, natural dyes began to be replaced by synthetic ones. Nowadays, there are more than 15,000 dyes of various shades belonging to different classes of compounds.
1.2. The concept of indicators.
Indicators means "pointers". These are substances that change color depending on whether they are in an acidic, alkaline or neutral environment. The most common indicators are litmus, phenolphthalein methyl orange.
The first acid-base indicator was litmus. Litmus is an aqueous infusion of a litmus lichen that grows on rocks in Scotland.
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.
If there are no real chemical indicators, to determine the acidity of the environment, you can successfully use ... home, field and garden flowers, and even the juice of many berries - cherries, chokeberries, currants. Pink, crimson or red geranium flowers, peony petals or colored peas will turn blue when dipped in an alkaline solution. Cherry and currant juice will also turn blue in an alkaline environment. On the contrary, in acid the same “reagents” will take on a pink-red color.
Plant acid-base indicators here - dyes -anthocyanins. It is anthocyanins that give various shades of pink, red, blue and purple to many flowers and fruits.
beet coloring matterbetaine or betanidine in the in a local environment it becomes discolored, and in an acidic environment it turns red. That is why borscht with sauerkraut has such an appetizing color.
1.3. 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. In our time, 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.
1.4. Hydrogen index.
The indicator paper universal has a scale for definition of the environment (рН).
Hydrogen indicator,pHis a value characterizing the concentration of hydrogen ions in solutions. This concept was introduced in Danish chemist . The indicator is called pH, according to the first letters of Latin wordspotentia hydrogeni is the strength of hydrogen, orpondus hydrogenii is the weight of hydrogen. Aqueous solutions can have a valuepHin the range 0-14. In pure water and neutral solutionspH=7, in acidic solutionspH<7 и в щелочных pH>7. QuantitiespHmeasured with acid-base indicators.
Table #1
The color of the indicator in different environments.
Name of the indicator
Indicator color in different environments
in sour
in neutral
in alkaline
methyl orange
Red
(pH < 3,1)
Orange
(3,1 < pH < 4,4)
Yellow
(pH > 4.4)
Phenolphthalein
Colorless
( pH< 8,0)
Colorless
(8,0 < pH < 9,8)
Crimson
( pH >9,8)
Litmus
Red
( pH< 5)
Purple
(5 < pH < 8 )
Blue
( pH > 8)
Hydrogen indicator - the most important characteristic biological fluids; blood, lymph, saliva, gastric, intestinal and cell juice. Therefore, it is often determined in clinical analyzes, assessing human health.
DesignationpHwidely used in chemistry, biology, medicine, agronomy, ecology and other areas of life. It is no coincidence that so much is said about him in the media, and even people far from chemistry are keenly interested in this concept. TV screens show how it changespHin a person’s mouth after brushing their teeth with such and such a paste or after chewing such and such a gum ... An absolutely neutral environment corresponds to the valuepHequal to exactly 7. The more acidic the solution, the lesspH, and in the presence of alkalipHbecomes more than 7.
II . Practical part.
2.1. Obtaining natural indicators.
To obtain natural indicators, we acted as follows. The test material was rubbed on a grater, then boiled, as this leads to the destruction of cell membranes, and anthocyanins freely leave the cells, coloring the water. The solutions were poured into a transparent container. To find out which decoction serves as an indicator for a particular medium and how its color changes, it was necessary to conduct a test. We took a few drops of a home-made indicator with a pipette and added them alternately to an acidic or alkaline solution. Table vinegar served as an acidic solution, and baking soda solution served as an alkaline solution. If, for example, a bright red beetroot decoction is added to them, then under the influence of vinegar it will turn red, soda - red-violet, and in water - pale pink, because. in water the medium is neutral.
The results of all these experiments were carefully recorded in table No. 2; we present a sample of it here.
Table number 2
Indicator
Mortar color
original
in an acidic environment
in an alkaline environment
Grape juice
Dark red
Red
Green
red beets
Red
bright red
Red - purple
onion purple
light purple
Pink
light green
Red-headed cabbage
Purple
Red
light green
Grape juice
Red
Red
Light green
Also, regular tea can be used at home as an indicator. We noticed that tea with lemon is much lighter than without lemon. In an acidic environment, it becomes colorless, and in an alkaline environment it becomes darker.
tea neutral environment tea in acidic and alkaline environment
2.2. Investigation of the medium of solutions by plant indicators.
First, it was necessary to repeat the safety rules for working with chemicals and equipment.
2.2.1. Chemical experiments with food.
We decided with the help of a natural indicator - a decoction of beets - to check the acidity of the environment of milk 2.5% and sour cream 20%. A few drops of beetroot decoction were added to the milk. The solution became pale pink. This means that the environment in milk is closer to neutral. The same experiment was repeated with sour cream. The color of sour cream after adding the natural indicator was deep pink. This is closer to a slightly acidic environment. The conclusion is this: milk is a neutral environment, and sour cream is an acidic environment. Grape juice gave interesting results. In an alkaline environment, the juice turned blue, in an acidic environment - red, in a neutral environment - pink. Next, we added grape juice to milk and sour cream. In milk, it became light green, and in sour cream - pale pink. This means that sour cream is slightly acidic.
Table No. 3
Research product
beet color
Wednesday
Milk 2.5%
Pale pink
Neutral
Sour cream 20%
Pink
slightly acidic
2.2.2. Chemical experiments with detergents.
Next, we decided to test the medium in soap and detergent. For this, the Tide powder, soap "DOVEand laundry soap. First prepared solutions of these detergents. An indicator was added to each solution - a decoction of beets. In the laundry soap, the indicator turned purple, and in the soap "DOVE» - pink. So in laundry soap it is strongly alkaline, and soap "DOVE» has a neutral environment. A very high alkali content in soap causes great harm to the skin of the hands. In "laundry soap" there is a high content of alkali, while in soap "DOVE» lowest alkali content (neutral medium). From this we can conclude: in soap "DOVE» the lowest alkali content, therefore, it is safer for the skin of the hands. Our indicator was added to the Tide powder solution. The solution turned purple, and after a few minutes it became colorless. This means that the solution of the powder is strongly alkaline. In this way, you can check the acidity of any detergent.
Table No. 4
Changing the color of the indicator in detergents
Test solution
Color
Wednesday
Tide Powder
purple
alkaline
Laundry soap
purple
alkaline
Soap "DOVE»
pink
neutral
Any work should result in practical value. In the process of experiments, somehow by itself, a proposal came to dye the eggs with our natural dyes. An egg mashed with beetroot juice turns burgundy. Onion peel - brown. Prepared indicators cannot be stored for a long time, they are destroyed in water. You can extend their action by soaking a filter paper with the extract, and then drying it. Keep these papers in a closed container.
Conclusions.
By studying the indicators, we came to the following conclusions:
Acid-base indicators are necessary in chemical analysis to determine the medium of solutions.
There are natural plants that exhibit the properties of acid-base indicators.
Brightly colored beets, tea and grape juice can be used as natural indicators.
Solutions of natural indicators can be prepared and used at home.
Natural indicators are also quite "accurate" determinants of the acidity of liquids, as are the most "professional" indicators: litmus, phenolphthalein and methyl orange.
Coloring substances of plants in an acidic environment give shades of red tones, in an alkaline environment - purple, and in a neutral environment - pink.
Conclusion.
In conclusion, I want to say that I have learnedidentify the environment of solutions, showing the effect of soap solutions on the skin of the hands, synthetic detergents on fabrics when washing clothes.
The result of this work (research) was the development of my creative thinking and practical activities, the formation of interest in the knowledge of chemical phenomena and their patterns.
In the end, I want to express my attitude to chemistry in the words of M. Gorky: “First of all and most carefully study chemistry. This is an amazing science, you know ... Her keen, bold look penetrates into the fiery mass of the sun and into the darkness of the earth's crust, into the invisible particles of your heart, and into the secrets of the structure of stone, and into the silent life of a tree. She looks everywhere and, everywhere discovering harmony, stubbornly seeks the beginning of life ... "
Bibliography
1. Alekseeva A. A. Medicinal plants. / A. A. Alekseeva Ulan-Ude: Buryat. book. publishing house, 1974.- 178 p.
2. Alikberova L. Yu. Entertaining chemistry / L. Yu. Alikberova M.: AST-PRESS, 1999. - 560 p.
3 . Janis V.K. 200 experiments / V.K. Janice M.: AST-PRESS, 1995. - 252 p.
4 . Kuznetsova N. E. Chemistry. Textbook for grade 10 / N.E. Kuznetsova M: Ventana-Count, 2005.- 156 p.
5. Nikolaev N.G. Local history / N.G. Nikolaev, E.V. Ishkova M.: Uchpedgiz, 1961.- 164p.
6 . Novikov V.S. School atlas - determinant of higher plants / V.S. Novikov, I.A. Gubanov M: Enlightenment, 1991. - 353 p.
7. Savina L. A. I know the world. Children's Encyclopedia Chemistry / L.Ya. Savina M: AST, 1997.- 356p.
8. Sinadsky Yu. V. Healing herbs / Yu.V. Sinadsky, V.A. Sinadskaya M: Pedagogy, M. 1991.- 287p.
9 . Somin L.E. Fascinating chemistry / L.E. Somin M.: Pedagogy, 1978.- 383 p.
Municipal budgetary educational institution
"Secondary school No. 22"
from. Knevichi of the Artemovsky city district
Indicators around us
Completed by: Kozlova Ksenia
student of 8 "A" class
Head: Klets Elena Pavlovna
chemistry and biology teacher
Artem, 2018
Content
Introduction - - - - - - - - - - 3
1. Literary review. - - - - - - - 4
1.1. History of opening indicators - - - - - - 4
1.2. Indicators in nature - - - - - - - 5
1.3. Indicators in chemistry lessons - - - - - 6
2. Materials and methods - - - - - - - - 8
2.1. Experiment in the school laboratory - - - - - 8
2.2. Processing of results - - - - - - 9
Conclusions - - - - - - - - - - 10
Conclusion - - - - - - - - - 10
References - - - - - - - 11
Introduction
Indicators are widely used in chemistry, including at school. Any student will say what phenolphthalein, litmus or methyl orange is.
Indicator - a device, device, substance that displays changes in any parameter of a controlled process or state of an object. 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 medium changes.
I was interested in the question: the juices of which 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 food?
Relevance of the topic: attracting the interest of schoolchildren to the popularization of organic chemistry through simple and safe experiments.
Objective : Obtain natural indicators from surrounding natural materials. To study their properties on the example of their use as indicators.
Tasks:
Study the literature on 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.
1. Literature review
1.1 History of opening indicators
For the first time, substances that change their color depending on the environment were discovered in the 17th century by the English chemist and physicist Robert Boyle. He has done thousands of experiments. Here is one of them.
Candles were burning in the laboratory, something was boiling in the retorts, when the gardener came in inopportunely. He brought a basket of violets. Boyle was very fond of flowers, but the experiment had to be started. He took some flowers, sniffed them and put them on the table. The experiment began, the flask was opened, caustic steam poured out of it. When the experiment was over, Boyle 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. The scientist ordered the assistant to prepare solutions, a flower was lowered 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 [1 ].
Boyle began to prepare infusions from other plants: medicinal herbs, tree bark, plant roots, etc. However, the most interesting was a purple infusion obtained from litmus lichen. Acids change its color to red, and alkalis to blue.
Boyle ordered paper to be soaked with this infusion and then dried. Thus, 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. Having poured out the infusion, Boyle filled the flask 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 testing and found that litmus turns blue in an alkaline medium. Thus, the first indicator for the detection of acids and alkalis was discovered, named after the lichen litmus. Since then, this indicator has been one of the indispensable indicators in various studies in the field of chemistry [2 ].
1.2 Indicators in nature
The plant kingdom is striking in its variety of colors. The color palette is diverse and is determined by the chemical composition of the cellular contents of each plant, which includes pigments. Pigments are organic compounds present in plant cells and tissues that color them. Pigments are located in chromoplasts. More than 150 types of pigments are known.
If there are no real chemical indicators, to determine the acidity of the environment, you can successfully use ... home, field and garden flowers, and even the juice of many berries - cherries, chokeberries, currants. Pink, raspberry or redgeranium flowers, petalspeonyorcolored peasturn blue when immersed in an alkaline solution. Juice will also turn blue in an alkaline environmentcherriesorcurrants. On the contrary, in acid, the same "reagents" will take on a pink-red color. Plant Acid-Base Indicators Here - Coloring Agents by Nameanthocyanins . Exactlyanthocyanins give a variety of shades of pink, red, blue and purple to many flowers and fruits.
beet coloring matterbetaine in an alkaline environment it becomes discolored, and in an acidic environment it turns red. That is why borscht with sauerkraut has such an appetizing color.
Plants with a high concentration of anthocyanins are popular in landscape design.
Carotenoids (from the Latin word "carrot") are natural pigments from yellow to red-orange in color, synthesized by higher plants, fungi, sponges, corals. Carotenoids are polyunsaturated compounds, in most cases they contain 40 carbon atoms in a molecule. These substances are unstable in the light, when heated, under the action of acids and alkalis. From plant materials, carotenoids can be isolated by extraction of organic solvents.
Natural dyes are found in flowers, fruits, and rhizomes of plants.
Unfortunately, almost all natural indicators have a serious drawback: their decoctions deteriorate rather quickly - turn sour or moldy. Another disadvantage is the too wide range of color change. At the same time, it is difficult or impossible to distinguish, for example, a neutral medium from a slightly acidic or slightly alkaline one.
1.3 Indicators in chemistry lessons
Indicators means "pointers". These are substances that change color depending on whether they are in an acidic, alkaline or neutral environment. The most common indicatorslitmus, phenolphthalein and methyl orange.
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.
Litmus - black powder. Soluble in water, 95% alcohol, acetone, glacial acetic acid. The color of the solution changes from red to blue.
In the laboratory, less common indicators can also be used: methyl violet, methyl red, thymolphthalein. Most indicators are used only in a narrow pH range, but there are also universal indicators that do not lose their properties at any values of the hydrogen index.[ ].
2. Materials and methods
2.1 Experiment in the school laboratory
For my research, I usedred onions and their husks, cherries, cranberries, beets and cauliflower.
For the preparation of vegetable indicatorsa small amount ofraw materialseach sampleIcrushedin a mortar, transferred to a test tubeflooded12 ml of water and boiled for 1-2 minutes. The resulting broths were cooled and filtered.(Fig. 1).
Having thus obtained solutions of indicators, I checked what color they have in different environments.
To obtain a solution with an acidic medium, citric acid was used, and with an alkaline one, baking soda was used.
The prepared solutions were tested for the acidity of the medium using a universal indicator, comparing their indicators with those of hydrochloric acid and alkali solution (Fig. 2).
I poured these solutions into test tubes for further experiment. For convenience, I divided the test tubes by color: with pink marking - soda solution, with yellow marking - citric acid solution. ViapipetteAndI added to solutionsa few drops of homemade indicator.
2.2 Handling results
The results of these experimentspresentedin tablese.
Table 1. Results
Raw materials for the preparation of the indicator
Natural indicator color
Staining in an acidic environment
Coloring in an alkaline environment
Red onion peel
Red
Red
brown green
Red onion
colorless
light pink
light yellow
Beet
bright red
bright red
Dark red
Cauliflower
colorless
light pink
colorless
Cranberry
bright red
bright red
dark blue
Cherry
Dark red
bright red
purple
The best result was obtained with a decoction of cranberries, cherries, red onion husks (Fig. 3)
conclusions
Received natural indicators from surrounding natural materials;
Studied their properties on the example of their use as indicators;
We studied the literature on indicators;
Conclusion
After doing research, I came to the following conclusions:
many natural plants have the properties of indicators that can change their color depending on the environment in which they fall;
the following natural raw materials can be used to make plant indicator solutions: berriescherries, cranberries, cauliflower, beets, red onions and their husks;
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.
This research should be continued in the summer when there are many flowering plants. The brightly colored flowers contain many different pigments that can be used as indicators and dyes.
Bibliography
1. Vetchinsky K.M. Vegetable indicator. M .: Education, 2002. - 256 p.
2. Vronsky V.A. vegetable indicator. - St. Petersburg: Parity, 2002. - 253 p.
3. Stepin B. D., Alikberova L. Yu. Entertaining tasks and spectacular experiments in chemistry. - M .: Bustard, 2002
4. Strempler G.I. Home laboratory. (Chemistry at leisure). - M., Enlightenment, Educational literature.-1996.
5. http://www.alhimik.ru/teleclass/glava5/gl-5-5.shtml
6. fb.ru/article/276377/chto -takoe -indikator -v -himii -opredelenie -primeryi- printsip -deystviya
"Secondary school No. 2 of Zhirnovsk"
Volgograd region
Research work in chemistry on the topic:
"Indicators in our life"
Completed by: student 8 "A" class MOU "Secondary School No. 2 of Zhirnovsk"
Danina Maria Vitalievna (14 years old)
Head: chemistry teacher Aleshkova Anastasia Sergeevna
Zhirnovsk, 2015
Introduction ………………………………………………………………………..3 – 4
Indicators ………………………………………………………. ………five
Chemical indicators. The history of the formation of indicators. ...5 – 7
natural indicators. Characterization and classification ……7 – 9
Experimental part ………………………………………………….10
Research methodology ……………………………………………...10
Results and discussion ……………………………………………………………………………………………………………………………………………………………12
Conclusion ………………………………………………………………………… 14
References ……………………………………………………………...15
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.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 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 contents of each plant. To be more precise, 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, flavonones, and others. The benefits of many plants are undeniable. Since ancient times, people have used plants as medicines. Therefore, it was not for nothing that traditional medicine based on the unique and medicinal properties of plants arose.
Why we chose this topic.
First, we are interested in the properties of plant objects.
Secondly, what is their role in such a science as chemistry?
What determines their indicator properties?
And, thirdly, how can their properties be used for medical purposes.
Therefore, we will consider such flavonoids as anthocyanins. Since they are ideal candidates for our study.
Relevance of the topic is that today more and more interested 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 study their properties.
Research objectives:
1) Analyze literature on plant physiology and biochemistry of indicators
2) Examine natural objects for the presence of indicators - anthocyanins;
3) Prove the indicator properties of plant pigments - anthocyanins;
4) Reveal the significance and biochemical role of natural objects containing anthocyanins.
object research is: lemon peel, carrot roots, beet roots, black tea, onion peel, flowers of Decembris, geraniums, gerberas and violets.
Indicators
Chemical indicators. The history of the formation of indicators
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 are able to 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 in ancient Rome, where it was used as a purple 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 was 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, hard work was in full swing: candles were burning, various substances were heated in retorts. A gardener entered Boyle's office and placed a basket of deep purple violets in the corner. At this time, Boyle was going to conduct an experiment to obtain sulfuric acid. Fascinated by the beauty and aroma of violets, the scientist, taking with him a bouquet, went to the laboratory. The technician informed Boyle that two bottles of hydrochloric acid had arrived yesterday from Amsterdam. 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 going to his study, he took his bouquet and noticed that the violets were slightly smoking from the splashes of acid that had fallen on them. To wash the flowers, he dipped them into a glass of water. After a while, he glanced at the glass of violets, and a miracle happened: the dark purple violets turned red. Naturally, the scientist began research. He discovered that other acids also turned violet petals red. He thought that if you make an infusion from the petals and add it to the test solution, you can find out whether it is sour or not. Boyle began to prepare infusions from other plants: medicinal herbs, tree bark, plant roots, etc. However, the most interesting was a purple infusion obtained from litmus lichen. Acids change its color to red, and alkalis to blue.
Boyle ordered paper to be soaked with this infusion and then dried. Thus, 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. Having poured out the infusion, Boyle filled the flask 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 testing and found that litmus turns blue in an alkaline medium. Thus, the first indicator for the detection of acids and alkalis was discovered, named after the lichen litmus. Since then, this indicator has been one of the indispensable indicators in various studies in the field of chemistry.”
Acid-base indicators.
Most often, acid-base indicators are used in laboratories. These include phenolphthalein, litmus, methyl orange, bromthymol blue, and others.
Acid-base indicators are organic compounds that can change color in solution when the acidity changes. They change color within fairly narrow pH ranges. There are many such indicators, and each of them has its own scope.
Such indicators are among the most stable and in demand in chemistry laboratories.
natural indicators. Characteristics and classification.
The pigments of many plants are able to 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 common name for natural pigments is flavonoids. This group includes carotenoids, xanthophylls, anthocyanins, respectively, which determine the yellow, orange, red, blue, and purple 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, 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 the color changes depending on the balance of acids and alkalis.
The structure of anthocyanins was established in 1913 by the German biochemist R. Wilstetter. 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: they become purple in a neutral environment, red in an acidic environment, and green-yellow in an alkaline environment.
Indicators allow you to quickly and fairly 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, natural indicators - 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 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.
experimental part
Research methodology.
Reagents: 1) water
2) 5% hydrochloric acid
3) 5% sodium hydroxide
Equipment and utensils: mortar, pestle, test tubes, pipette, tripod
Material under study: plant objects
Results and discussion
Table 2.1
Changing the color of natural indicators in an acid-alkaline environment
| № | Material under study | Color change in an acidic environment | Color change in an alkaline environment | Natural color solution |
| 1 | Violet Indoor | Crimson | discolored | Blue |
| 2 | Geranium Indoor (light pink) | Crimson | discolored | Light pink |
| 3 | Geranium Indoor (dark pink) | Crimson | discolored | Dark pink |
| 4 | Decembris | Crimson | discolored | Purple |
| 5 | Gerbera | Crimson | discolored | Brown |
| 6 | Beet | Dark red | discolored | Dark red |
| 7 | Common carrot | pink shade | discolored | Pale orange |
| 8 | Onion | pink shade | discolored | Yellow |
| 9 | lemon zest | Did not change | Bright yellow | pale yellow |
| 10 | Tea | discolored | Dark brown | Brown |
As a result, we found that the color of plant pigments under the action of acids and alkalis changes depending on the type of plant and the color of the original pigments. For example, common carrot carotenoids practically do not give a color change with a change in acidity. And since the studied pigments of onion peel and lemon peel are very similar in color to carrot pigments and, like carrots, did not change color with a change in acidity, we can assume that their color is also due to carotenoids. Carotenoids are unsuitable as acid-base indicators.
Plants in which anthocyanins were present changed their color under the influence of acids and alkalis. For example, room violet, room geranium, decabris, gerbera, beets in an alkaline environment became discolored, and in an acidic environment they acquired a crimson color. Regular tea can also be used at home as a natural indicator. Have you noticed that tea with lemon is much lighter than without lemon. In an acidic environment, it becomes colorless, and in an alkaline environment it becomes darker.
conclusions
The literature on the biochemistry of indicators was analyzed
The indicator properties of the studied objects are proved
A regularity has been revealed: all these natural objects in an acidic environment are predominantly colored red, and in an alkaline environment they become discolored. Which proves the presence of anthocyanins.
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 other various studies.
And also anthocyanins are 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 a long and healthy life of cells, which means they 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 advise eating only half a glass of blueberries a day - fresh or frozen. Therefore, preparations containing blueberries are most in demand in medicine.
Bibliography:
Vetchinsky K.M. Vegetable indicator. M .: Education, 2002. - 256 p.
Vronsky V.A. vegetable indicator. - St. Petersburg: Parity, 2002. - 253 p.
Galin G.A. Plants help geologists. - M.: Nauka, 1989. - 99s.
Zacer L.M. On the question of the use of indicator plants in chemistry. - M.: Nauka, 2000. - 253 p.
Leenson I.A. Entertaining chemistry: 8-11 grades. - M.: Enlightenment, 2001. - 102p.
Sokolov V.A. Natural dyes. M .: Enlightenment, 1997.
Journal "Chemistry at school" No. 2, No. 8 - 2002.
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Introduction
In our life we meet with various substances that surround us. This year we started to study 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?
In the lessons when studying the topic “The most important classes of inorganic compounds”, I got acquainted with indicators - litmus, phenolphthalein and methyl orange. What are indicators? Indicators are substances that change color depending on the medium of the solution. With the help of indicators, you can determine the environment of the solution.
I decided to find out as much as possible about these amazing substances, and whether it is possible to use the natural materials that are at home as indicators.
Relevance of the topic: Today, the properties of plants and the possibilities of their application in chemistry, biology and medicine are of great interest.
Objective: to study natural indicators and how we can use them in everyday life.
To achieve the goal, the following tasks were set:
Learn about indicators as chemicals.
Study natural indicators.
Find out how you can apply knowledge about natural indicators in everyday life.
To achieve my goals, I studied the literature in the library and the chemistry classroom, used materials from Internet sites, and also used the methods of observation, experiment, comparison, and analysis.
My work consists of three chapters. In the first chapter, I considered the variety of indicators and their chemical nature. In the second, what plants are indicators and their role in nature and human life. In the third chapter, my practical research.
1.Chemical indicators
1.1 History of opening indicators
Indicators (from lat.Indicator - pointer) - substances that allow you to monitor the composition of the environment or the progress of a chemical reaction. To date, 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.
The pigments of many plants are able to change color depending on the acidity of the cell sap. Therefore, 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 commonly used vegetable acid-base indicator in chemistry is litmus. It was already known in ancient Egypt and in ancient Rome, where it was used as a purple substitute for expensive purple. The use of pigments to determine the medium of a solution was first scientifically applied by Robert Boyle (1627 - 1691). 1663, as usual, hard work was in full swing in the laboratory: candles were burning, various substances were heated in retorts. A gardener came into Boyle's office and placed a basket of magnificent deep purple violets in a corner. At this time, Boyle was going to conduct an experiment to obtain sulfuric acid. Fascinated by the beauty and aroma of violets, the scientist, taking with him a bouquet, went to the laboratory. His lab assistant, William, told Boyle that two bottles of hydrochloric acid had arrived yesterday from Amsterdam. Boyle wanted to look at this acid, and to help William pour the acid, he put the violets on the table. Then he took a bouquet from the table and went to the office. Here Boyle noticed that the violets were slightly smoking from the splashes of acid that fell on them. To wash the flowers, Boyle dipped them into a glass of water. After a while, he glanced at the glass of violets, and a miracle happened: the dark purple violets turned red. Naturally, Boyle, as a true scientist, could not ignore such a case and began research. He discovered that other acids also turned violet petals red. The scientist thought that if you make an infusion from the petals and add a little to the test solution, you can find out whether it is sour or not. Boyle began to prepare infusions from medicinal herbs, tree bark, plant roots. However, the most interesting was a purple infusion obtained from a certain lichen. Acids changed its color to red, and alkalis to blue. Boyle ordered paper to be soaked with this infusion and then dried. Thus, the first litmus test was created, which is now available in any chemical laboratory. Thus, one of the first substances was discovered, which Boyle already then called indicators.
1.2. Varieties of indicators
The Chemical Encyclopedic Dictionary distinguishes among the indicators: adsorption, isotopic, acid-base, redox, complexometric, luminescent indicators.
My work is devoted to acid-base indicators. With the development of chemistry, the number of acid-base indicators grew. Indicators obtained as a result of chemical synthesis: phenolphthalein, introduced into science in 1871 by the German chemist A. Bayer, and methyl orange, discovered in 1877.
Nowadays, several hundred artificially synthesized acid-base indicators are known. We can meet some of them in the school chemistry laboratory. Phenolphthalein - in chemistry - an indicator expressed as colorless crystals without taste and smell. Melting point - 259-263°C. In medicine, it is a laxative (the outdated name is purgen). In an alkaline environment, it turns into a bright crimson color, and in a neutral and acidic environment it is colorless. Litmus (lakmoid) is an indicator extracted from some lichens, and turns red under the action of acids, and blue under the action of alkalis. Methyl orange is an acid-base indicator, a synthetic organic dye from the group of azo dyes. It is pink in acids and yellow in alkalis. Depending on the acidity of the medium, the brilliant green dye also changes color (its alcohol solution is used as a disinfectant - “brilliant green”). In order to check this, you need to prepare a dilute solution of brilliant green: pour a few milliliters of water into a test tube and add one or two drops of a pharmaceutical preparation. The solution acquires a beautiful green - blue color. In a strongly acidic environment, its color changes to yellow, and the alkaline solution becomes colorless.
Table of some chemical indicators:
|
Indicator |
pH interval |
Color change |
|
thymol blue |
Red - yellow |
|
|
methyl orange |
Red - orange yellow |
|
|
methyl red |
Red - yellow |
|
|
Red - blue |
||
|
thymol blue |
Yellow - blue |
|
|
Phenolphthalein |
Colorless - red |
|
|
thymolphthalein |
Colorless - blue |
The table lists acid-base indicators common in laboratory practice in ascending order of pH values that cause a color change. The first color corresponds to the pH values before the interval, the second color - after the interval.
However, most often in laboratory practice, a universal indicator is used - a mixture of several acid-base indicators. It makes it easy to determine not only the nature of the medium (acidic, neutral, alkaline), but also the acidity (pH) value of the solution.
2. Indicators in nature
2.1. Anthocyanins and carotenoids
Nature is a unique creation of the Universe. This world is beautiful, mysterious and complex. The plant kingdom is striking in its variety of colors. The color palette is diverse and is determined by the chemical composition of the cellular content of each plant, which includes pigments - bioflavonoids. Pigments are organic compounds present in plant cells and tissues that color them. Pigments are located in chromoplasts. More than 150 types of pigments are known. Bioflavonoids include, for example, anthocyanins and carotenoids.
Anthocyanins are widely distributed coloring substances in the plant kingdom. Anthocyanins (from the Greek words for "flower" and "blue") are natural colorants. Anthocyanins give plants a color ranging from pink to dark purple.
The structure of anthocyanins was established in 1913 by the German biochemist R. Wilstetter. The first chemical synthesis was carried out in 1928 by the English chemist R. Robinson. They are most often dissolved in cell sap, sometimes found in the form of small crystals. Anthocyanins are easily extracted from any blue or red parts of the plant. If, for example, you boil chopped beet roots or red cabbage leaves in a small amount of water, it will soon turn purple from anthocyanins.
The presence of anthocyanins in the cell sap of plants gives the flowers of bluebells a blue color, violets - purple, forget-me-nots - sky blue, tulips, peonies, roses, dahlias - red, and flowers of carnations, phloxes, gladioli - pink. Why is this dye so many-sided? The fact is that anthocyanin, depending on the environment in which it is located (acidic, neutral or alkaline), is able to quickly change its shade. Anthocyanins have good indicator properties: they become purple in a neutral environment, red in an acidic environment, and green-yellow in an alkaline environment. Unfortunately, almost all natural indicators have a serious drawback: their decoctions deteriorate rather quickly - turn sour or moldy (see Appendix 1). Another disadvantage 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 slightly acidic one or a slightly alkaline one from a strongly alkaline one.
Plants with a high concentration of anthocyanins are popular in landscape design.
Carotenoids (from the Latin word "carrot") are natural pigments from yellow to red-orange in color, synthesized by higher plants, fungi, sponges, corals. Carotenoids are polyunsaturated compounds, in most cases they contain 40 carbon atoms in a molecule. These substances are unstable in the light, when heated, under the action of acids and alkalis. Carotenoids can be isolated from plant materials by extraction with organic solvents.
Natural dyes are found in flowers, fruits, and rhizomes of plants.
2.2 Indicator geobotany
In ancient folk beliefs, it was often said about herbs and trees that could reveal various treasures. There are many books on flower geologists. In "Ural Tales" P.P. Bazhov wrote about magical flowers and "gap-grass" that open storerooms of copper, iron, and gold to people. In recent years, links between certain plants and deposits of certain minerals have been scientifically substantiated. Tricolor field violets, pansies or field horsetail tell a person that the soil, albeit in a minimal amount, contains zinc and gold. Pink bindweed and golden coltsfoot grow in whole clearings on clay and calcareous soils. Often, by the ugly development of some plants, one can learn about the presence of many minerals in the soil. For example, on soils with a normal content of boron, plants such as wormwood, prutnyak, saltwort grow tall, and on soils with a high content of this element, these plants become dwarfed. The altered shape of the poppy petals indicates that there are deposits of lead and zinc underground.
It will help you find water and determine whether it is fresh or salty, licorice is a large plant with dark greens and red-purple flower tassels. If the plant blooms magnificently - the water is fresh, if it is weak and a light coating appears on the leaves - the water is salty.
Sometimes so many valuable elements accumulate in plants that they themselves become “ore”. The very rare metal beryllium is accumulated by cranberries, larch bark, and Amur adonis. It turned out that ordinary quinoa contains a lot of lead, and sage contains germanium and bismuth. Wormwood turned out to be the best scout. Above the ore zones, it contains a lot of mercury, lead, zinc, silver, antimony, and arsenic. The accumulation of ore elements and heavy metals does not pass without a trace for the plant, appearance it changes. Boron inhibits plant growth and causes branching. Plants do not bloom, roots die. An excess of beryllium changes the shape of branches in young pines. If there is a lot of iron in the soil, the plants have bright green foliage and appear strong and healthy. And with the advent of autumn, they are the first to turn yellow and lose their leaves. A high concentration of manganese in the soil discolors the leaves.
This means that by studying the chemical composition of plants, new deposits can be discovered. And now the geobotanical method is still used in practice. There was even a science - “indicator geobotany”, which studies plants that are sensitive to changes environment and helping to discover the wealth of the earth's interior.
3. Practical part: the study of natural indicators
I decided to find out which of the edible plants available at home can be used as acid-base indicators. For the experience, I took frozen blueberries, strawberries, cherries, raspberries, beet roots.
For the experiments, I used the following materials and equipment: glasses, funnels, test tubes, mortars with pestles, a knife, filter paper, water, ethyl alcohol, solutions of sodium hydroxide and hydrochloric acid.
I ground the berries in a mortar, crushed the beets with a grater. The extraction of the pigment (paint) from the crushed raw materials was carried out in two ways: using alcohol and water (see Appendix 2).
Colored alcohol and aqueous solutions were filtered using a paper filter and gauze to rid the infusion of plant particles. The entire chemical experiment was carried out in school office chemistry together with the supervisor.
Experience 1. Investigation of the change in color of prepared solutions depending on the medium.
Alkali and acid solutions were poured into test tubes, and solutions of natural indicators were added. A change in the color of the solutions was noted (see Appendix 3).
Research results.
Scale of color transitions of infusions of some plants in various environments.
|
Plants |
Acidic pH< 7 |
Neutral medium pH = 7 |
Alkaline pH> 7 |
|
blue green |
|||
|
burgundy |
|||
|
Dark red |
Light red (scarlet) |
||
|
Strawberry |
Experience 2. Investigation of the environment of solutions of household chemicals.
With the help of natural prepared indicators, I examined the environment of the shampoo that I use at home, baby soap, washing milk, dishwashing detergent (see Appendix 4).
Research results.
As a result of the study, I concluded that the shampoo and facial wash are quite suitable for use. But the dishwashing detergent is alkaline in nature and can affect the skin of the hands, because. Our skin is slightly acidic.
Experience3. Heating the beetroot solution to a boil.
An aqueous solution of beets was heated to a boil, and the color changed from rich red to pale red. When hydrochloric acid was added, the color returned and even became more pronounced. This happens when cooking borscht. To return a beautiful rich color, you can add a little malic or acetic acid.
Conclusion
This work turned out to be very interesting and useful. Causes a desire to learn and get more information about the use of plants. As a result, it has been proven that many plants contain anthocyanins, thanks to which they can be natural indicators. They can be used both in everyday life and in chemistry for research. And I also learned that when 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. They 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.
The surface of our skin is slightly acidic, which protects it from bacteria, and after studying the environment of personal care solutions, I came to the conclusion that frequent use of soap, especially by adolescents, adversely affects the skin. The skin of the hands is also affected by washing powder, dishwashing detergent, as they have an alkaline environment.
So, I came to the conclusion:
The color of leaves, fruits, flowers of plants is determined by the presence of pigments belonging to the group of anthocyanins. Anthocyanins are found in cell sap and are highly soluble in water.
Representatives of the studied plants (cherries, raspberries, beets, strawberries, blueberries) can be used as indicators.
Plant indicators are available, safe to use, economical.
It was not in vain that I worked on this topic, since my small discoveries will be useful not only for me, but also for other students.
In summer, you can pick flowers and berries in the garden and in the forest. These can be irises, pansies, tulips, raspberries, cherries, etc. Dry the collected petals and fruits for future use (fruits can be frozen), and you can safely use them as indicators.
Bibliography
IN AND. Artamonov Green oracles. - Publishing house "Thought", 1989.
L.A. Savina I know the world. Children's encyclopedia. Chemistry. - M.: AST, 1996.
B.D. Stepin, L.Yu. Alikberova Entertaining tasks and spectacular experiments in chemistry. - M.: Bustard, 2002.
G.I. Strempler. Home laboratory. (Chemistry at leisure). - M., Education, Educational literature. - 1996.
Encyclopedic Dictionary of a Young Chemist. - M.: Pedagogy, 1982.
Internet resources
6.1 www.alhimik.ru
6.2 http://xumuktutor.ru/e-journal/2011/10/16/robert_boyle/
6.3http://www.inflora.ru/cosmetics/cosmetics258.html
Applications
Photographic report on the conducted research.
Attachment 1.
Photo of alcohol and aqueous solution on the eighth day after preparation.
Appendix 2
Photo of the process of preparing solutions of natural indicators.
Appendix 3
Photo of the experiment “Research on the change in color of prepared solutions depending on the medium (alkaline, acidic).
Appendix 4
Photo of the experiment "Study of the environment of solutions of household chemicals ».
1. Dishwashing liquid
2.Foam for washing
3. Shampoo
4. Washing powder
5. Laundry soap
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. In our time, 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 investigated 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 medium. The results of the obtained studies were entered in the table
| Object under study | Initial color of the solution in a neutral medium | Staining in an acidic environment | Coloring in an alkaline environment |
| 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) | |||
| Carrot (juice) | orange | ||
| Beet (juice) | |||
| Dandelion | yellow-green | light yellow | dark yellow |
| blackcurrant berries | |||
| raspberries | |||
| Geranium (bright pink flowers) | hot pink | hot pink | light brown |
| Geranium (white flowers) | white | light yellow | white |
| Pansies (violet flowers) | purple | hot pink | emerald green |
| Pansies (yellow flowers with a brown center) | gray | bright green | hot pink |
| Hibiscus |
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