|
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. *****
Municipal budgetary educational institution "Secondary school No. 22" With. Knevichi Artemovsky urban district Project work Indicators around us Completed by: Kozlova Ksenia student of 8th grade "A" Head: Klyots Elena Pavlovna teacher of chemistry and biology Artem, 2018 Content Introduction - - - - - - - - - - 3 1. Literature review. - - - - - - - 4 1.1. History of indicator opening - - - - - - 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 results - - - - - - 9 Conclusions - - - - - - - - - - 10 Conclusion - - - - - - - - - 10 References - - - - - - - 11 Introduction Indicators are widely used in chemistry, including in school. Any schoolchild will tell you what phenolphthalein, litmus or methyl orange are. An indicator is a device, device, substance that displays changes in any parameter of a controlled process or the state of an object. 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 plant juices 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? Relevance of the topic:
attracting the interest of schoolchildren to popularize organic chemistry through simple and safe experiments. Goal of the work
: Obtain natural indicators from surrounding natural materials. Study their properties using the example of their use as indicators. Tasks:
Study the literature on indicators; Familiarize yourself with their opening and functions; Learn to identify indicators from natural objects; Investigate the effect of natural indicators in various environments. 1. Literature review 1.1 History of the discovery of indicators Substances that change 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. The scientist ordered his assistant to prepare solutions, and dropped a flower 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 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 [2
].
1.2 Indicators in nature The plant kingdom amazes with its variety of colors. The color palette is varied 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, you can successfully use... home, wild and garden flowers and even the juice of many berries - cherries, chokeberries, currants - to determine the acidity of the environment. Pink, crimson or redgeranium flowers, petalspeonyorcolored peaswill turn blue if placed in an alkaline solution. Juice will also turn blue in an alkaline environment.cherriesorcurrants. On the contrary, in acid the same “reagents” will take on a pink-red color. Plant acid-base indicators here are colorants namedanthocyanins
. Exactlyanthocyanins
impart various 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's why borscht with sauerkraut has such an appetizing color. Plants with high concentrations of anthocyanins are popular in landscape design. Carotenoids (from the Latin word “carrot”) are natural pigments from yellow to red-orange, synthesized by higher plants, fungi, sponges, and corals. Carotenoids are polyunsaturated compounds, in most cases containing 40 carbon atoms per molecule. These substances are unstable in light, when heated, and when exposed to 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. 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 environment 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 under the name "purgen") -
white or white with a slightly yellowish tint, finely crystalline powder. Soluble in 95% alcohol, practically insoluble in water. Colorless phenolphthalein is colorless in acidic and neutral environments, but turns crimson in an alkaline environment. Therefore, phenolphthalein is used to determine the alkaline environment. Methyl orange
- orange crystalline powder. Moderately soluble in water, easily 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. Transition of solution color from red to blue. Less common indicators can also be used in laboratory conditions: 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 value of the hydrogen index[
].
2. Materials and methods 2.1 Experiment in the school laboratory For research work I usedred onions and their peels, cherries, cranberries, beets and cauliflower.
For preparing plant indicatorsa small amount ofraw materialseach sampleIcrushedin a mortar,
transferred to a test tubeflooded12
ml of water and boiled for 1-2 minutes. The resulting decoctions were cooled and filtered(Fig. 1).
Having thus obtained the indicator solutions, I checked what color they had in different environments. To obtain a solution with an acidic environment, citric acid was used, and with an alkaline solution, baking soda was used. The prepared solutions were checked 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: those with pink markings are a soda solution, and those with yellow markings are a citric acid solution. By usingpipetteAndI added to the solutions according toa few drops of homemade indicator.
2.2 Processing of results The results of these experimentspresentedin tablese.
Table 1. Results Raw materials for preparing the indicator
Natural indicator color
Coloring in an acidic environment
Alkaline painting
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 Navy blue Cherry Dark red bright red violet The best result was obtained with a decoction of cranberries, cherries, and red onion peels (Fig. 3)
 conclusions Obtained natural indicators from surrounding natural materials; We studied their properties using the example of their use as indicators; We studied the literature on indicators;
Conclusion After conducting research work, I came to the following conclusions: many natural plants have indicator properties that can change their color depending on the environment in which they find themselves; The following natural raw materials can be used to produce solutions of plant indicators: berriescherries,
cranberries,
cauliflower, beets, red onions and their peels;
homemade 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 needs to be continued in the summer when there are many flowering plants. Brightly colored flowers contain many different pigments that can be indicators and used as dyes. Bibliography 1.
Vetchinsky K.M. Plant indicator. M.: Education, 2002. – 256 p. 2. Vronsky V.A. Plant 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.
Shtrempler G.I. Home laboratory. (Chemistry at leisure). - M., Education, 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
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 known, 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. 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 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 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.
Slide 1"Natural indicators" RESEARCH WORK
The work was carried out by 11th grade students of the Municipal Autonomous Educational Institution Lyubokhonskaya Secondary School named after twice Hero of the Soviet Union A.A. Golovacheva Elena Alekseevna Gunko and Elena Viktorovna Kovalchuk, a teacher of biology and chemistry.
Municipal autonomous educational institution Lyubokhonskaya secondary school named after twice Hero of the Soviet Union A.A. Golovachev.
village Lyubohna, 2013
Slide 2
CONTENT
Chapter 1. Introduction Chapter 2. Main part 2.1. From the history of indicators. Classification of indicators. 2.2. Natural indicators. Biochemical role of natural indicators. Requirements for indicators. Chapter 3. Experimental part 3.1. Methods for producing indicators from natural raw materials. 3.2. Table with research results. 3.3. Determination of the environment of dishwashing detergent solutions using plant indicators. 4. Conclusion. 5. Recommendations. 6. Literature.
Slide 3
1. Introduction
Indicators are substances that change their color depending on the reaction of the environment. The name "indicators" comes from the Latin word indicator, which means "pointer". In a chemical laboratory or factory, indicators will tell you in a visual form whether a chemical reaction has been completed or not, whether one reagent has been added to another is enough or whether more needs to be added. When studying acids and bases in chemistry lessons, I learned that the juices of brightly colored berries, fruits and flowers have the properties of acid-base indicators, that is, they change their color when the acidity of the environment changes. I was interested in the question: what plants can be used as indicators? Is it possible to prepare solutions of plant indicators yourself? And can the prepared indicator solutions be used to determine the reaction of dishwashing detergents in order to determine whether they have a negative effect on the skin of the hands? The relevance of the topic lies in the fact that the properties of plant objects can be used for application in various fields of science, such as, for example, chemistry.
Slide 4
1. Introduction
Purpose of the work: with the help of research, prove the presence of natural indicators in plant objects, study their properties, and use them to determine the reaction of the environment in solutions of dishwashing detergents. Research objectives: 1) Study literary sources on the topic; 2) Explore natural objects for the presence of indicators; 3) Study the properties of indicators contained in natural objects; 4) Conduct a study to determine the reaction of the environment of dishwashing detergent solutions. Objects of research: cherry, strawberry, rowan, blueberry, lingonberry, blackberry, chokeberry, black currant; leaves of red cabbage, parsley, black currant; fruits: beets; flowers: red rose, red geranium, multi-colored carnation. Research hypothesis: if plants change color in different environments, then they can be used as indicators Research methods: 1. Study of scientific literature on this issue 2. Qualitative analysis. 3. Observation.
Slide 5
2.1. From the history of indicators
The history of indicators begins in the 17th century. Back in 1640, botanists described heliotrope, a fragrant plant with dark purple flowers (see picture), from which a dye was isolated. This dye, along with violet juice, became widely used by chemists as an indicator. You can read about this in the works 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. 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. Thus, the first indicator for detecting acids and bases was discovered, named litmus after the lichen. Phenolphthalein, which is used in the form of an alcohol solution, acquires a crimson color in an alkaline environment, but 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, a future Nobel Prize winner. As for the methyl orange indicator, discovered in 1887, it is truly orange in a neutral environment. In acids its color becomes pink-crimson, and in alkalis it turns yellow.
Slide 6
2.1. Classification of indicators
Some of the most common are acid-base indicators, which change color depending on the acidity of the solution. 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. In addition to acid-base indicators, other types of indicators are also used. Redox indicators change their color depending on whether an oxidizing agent or a 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 in color, while the reduced form is colorless. Complexometric indicators - substances that form colored complex compounds with metal ions - have become widespread. Some substances are adsorbed on the surface of the sediment, changing its color; such indicators are called adsorption indicators. When determining the environment of turbid or colored solutions, in which it is almost impossible to notice a change in color of conventional acid-base indicators, fluorescent indicators are used. 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. Universal indicators are often used - a mixture 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 (for example, from 1 to 11). Strips of paper are often impregnated with a solution of a universal indicator, which allows you to quickly (albeit with not very high accuracy) determine the pH of the solution being analyzed by comparing the color of the strip soaked in the solution with a reference color scale.
Slide 7
2.2 Natural indicators
If there are no real chemical indicators, then indicators isolated from natural raw materials can be successfully used to determine the 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 influence and, when exposed to an acidic or alkaline environment, they visually signal this. Such pigments are, first of all, anthocyanins: in a neutral environment they acquire a purple color, in an acidic environment - red, in an alkaline environment - green-yellow. 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 associated with 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.
Slide 8
2.2 Biochemical role of indicators
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 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.
Slide 9
2.2 Requirements for indicators
In order for any substance to serve as an indicator, it must satisfy the following necessary conditions: 1) must be a weak acid or a weak base; 2) its molecules and ions must have different colors; 3) their color must be extremely intense in order to be noticeable when a small amount of indicator is added to the test solution. Natural indicators have a serious drawback: their decoctions deteriorate quite quickly - they turn sour or mold (alcohol solutions are more stable). 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.
Slide 10
3.1. Own research
Over the summer I prepared indicators. The starting materials were plants. From all the collected plants, I received extracts one by one. To do this, I crushed the fruits, filled them with water and boiled them for 1-2 minutes. Then the solution was cooled and filtered. The resulting filtrate was diluted with alcohol at the rate of two volumes of filtrate and one volume of alcohol in order to protect it from spoilage. Extracts from flower petals and leaves were prepared in the same way. To prepare indicators, chemical glassware was used: test tubes, beakers, pipettes, funnels, filter paper, and a water bath. Distilled water and solutions with acidic and alkaline media were also required. The acidic solution was table vinegar (9%), and the alkaline solution was a solution of washing (soda ash). The prepared plant indicators were tested when exposed to acidic and alkaline solutions. The fruits, petals, leaves, and flowers of the following plants were examined: cherry, strawberry, blueberry, lingonberry, blackberry, chokeberry, beetroot, black currant, clove, red rose, red cabbage, red geranium, parsley, rowan. The results of the study are listed in Table 1.
Slide 11
3.2. Results of the study of indicator plants TABLE 1:
RAW MATERIALS FOR PREPARING INDICATORS NATURAL COLOR OF INDICATOR COLOR OF SOLUTION COLOR OF SOLUTION
RAW MATERIALS FOR PREPARATION OF INDICATORS NATURAL COLOR OF INDICATOR in an acidic environment (pH > 7) in an alkaline environment (pH Cherry (berries) Dark red Bright red Dirty green
Strawberry (berries) Pink Orange Light brown
Rowan (berries) Red Raspberry Pink
Blueberries (berries) Light purple Violet Dirty green
Lingonberry (berries) Dark red Yellow Orange
Blackberries (berries) Dark purple Red Brown
Chokeberry (berries) Burgundy Red Dirty green
Beetroot (fruit) Ruby Bright red Yellow
Red cabbage (leaves) Dark purple Green Lilac
Black currant (berries) Burgundy Red Green
Blackcurrant (leaves) Yellow-green Yellow Brown
Parsley (leaves) Yellow-green Light brown Yellow
Red rose (flowers) Pink Burgundy Bright red
Multi-colored carnation (flowers) Brown Pale pink Yellow
Red geranium (flowers) Red Orange Light brown
Slide 12
3.3. Determination of the environment of dishwashing detergent solutions using plant indicators In biology class, 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 dishwashing detergents, we disrupt the normal acidic environment of the skin on our hands. To protect the skin of your hands from negative effects, dishwashing detergents must have a pH value that corresponds to the pH value of the acid mantle of the epidermis. Using prepared solutions of natural indicators, I checked what kind of environment different dishwashing detergents have.
Slide 13
3.3. Reaction of the environment of dishwashing detergent solutions TABLE 2:
No. Dish detergent Plant indicator Indicator color Solution medium
1 “Myth” Red cabbage decoction Pale green Slightly alkaline
2 “Fairy” Red cabbage decoction Green Alkaline
3 “AOS” Strawberry decoction Pale yellow Slightly alkaline
4 “Pril” Chokeberry berry decoction Pale pink Slightly acidic
Slide 14
4. Conclusion After conducting 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 find themselves; - solutions of plant indicators can be used, for example, as acid-base indicators to determine the environment of dishwashing detergent solutions at home; - homemade indicators from natural raw materials can be used in chemistry lessons in schools if there is a problem of providing the school with chemical reagents. Based on the results of the 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 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.
Slide 15
1) Natural indicators can be used in chemistry lessons and elective courses. 2) Plant indicators can also be used in everyday life. 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. 3) To determine the composition of drugs used for treatment, natural indicators can be used. Many drugs are acids, salts and bases. By studying their properties, you can protect yourself. For example, aspirin (acetylsalicylic acid), many vitamins cannot be taken on an empty stomach, since the acids in their composition will damage the gastric mucosa. 4) The results of the research work can be used to determine the pH (hydrogen value) of various solutions, for example, dairy products, broths, lemonade and others, as well as to determine the acidity of the soil, since on the same soil, depending on its acidity, there is one type plants can produce high yields, while others will be depressed. 5) Dishwashing detergents “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; 6) In the poem “Blue Roses” by the famous English poet R. Kipling, there are the following lines: Once upon a time, I brought a whole heap of red roses to my dear one. She didn’t take it - and in her blue tears, find her roses. I have traveled all over the world in vain - there are no blue roses under the sun. Of course, there are no crimson cornflowers and blue lilies of the valley, but you can give the flowers a fantastic color. Pour concentrated ammonia into the cylinder and place a red rose flower. After a few minutes, a color change can be observed. When interacting with ammonia vapor, the color of the red rose turns blue.
Slide 16
6. References 1. Alikberova L.Yu. Entertaining chemistry. – M.: AST-PRESS, 2002. 2. Alikberova L.Yu. Entertaining chemistry. A book for students, teachers and parents. – M.: AST-PRESS, 1999. 3. Oganesyan E.T. A guide to chemistry for university applicants. – M.: Higher School, 1998. 4. Savina L.A. I'm exploring the world. Children's encyclopedia. Chemistry. – M.: AST, 1996. 5. New encyclopedic dictionary. – M.: Great Russian Encyclopedia. Rinol Classic, 2000. 6. Encyclopedic dictionary of a young chemist. – M.: Pedagogika, 1982. 7. Stepin B.D., Alikberova L.Yu. Entertaining tasks and spectacular experiments in chemistry. – M.: Bustard, 2002. 8. Internet resources. 9. Pilipenko A.T. "Handbook of Elementary Chemistry". Kyiv "Naukova Duma". 1973 Pages 164 -167. 10. Baykova V.M. "Chemistry after school." 1976 Page 90-95. 11. Scientific and practical magazine “Chemistry for schoolchildren” No. 4 2007. p.60 12. Educational and methodological newspaper for chemistry teachers “First of September”, No. 22, 2007. 13. Balaev I.I. "Home experiment in chemistry." 14. Nazarova T.S., Grabetsky A.A. “Chemical experiment at school” Moscow. 1987 15. Information from the website alchemic.ru “Good advice.”
|
