Chemistry In Everyday Life
Class 6 | Science — Chemistry | Unit 3
Class 6 Unit 3 Science
Unit 3 Chemistry in Everyday Life
Learning Objectives
To understand the importance of science in everyday life
To understand the preparation of soaps and detergents
To know about kinds of fertilizers and its uses
To know about uses of cement, gypsum, Epsom, and plaster of paris
To know about uses of phenols and adhesives in day to day life
Introduction
We have studied earlier about the physical changes and chemical changes. Can you identify, from the following list which are physical changes and which are chemical changes?
- breaking of a stick into two pieces
- burning of a paper
- tearing paper into small pieces
- dissolving sugar in water
- burning of petrol or LPG gas
- preparation of tea
- water boiling into water vapour
- coconut oil becoming solid during winter
Can you see the important difference between the chemical change and physical change? When you cut a paper into two, both are still paper pieces, but once you burn it, there is no longer the paper, only some ash and the smoke are left. Chemical change results in the change of the substance; in physical change only the shape, size or volume changes; the state of the matter may also change, from liquid to gas or from liquid to solid, however the substance remains, chemically as it is.
Let us do the following experiment. Add a pinch of turmeric powder to water; water turns yellow. Take a small quantity of soap water in a beaker and add a pinch of turmeric powder to it. Now, what happens? Is there any change in colour of the solution? Is it also turning to yellow or to some other colour? Try adding turmeric powder to various household liquids and observe the result. Try it on, say, tamarind extract. Try it on with cleaning liquids in the house. Does it change the colour? Chemists identify turmeric powder as a 'natural indicator'. The change in colour indicates that the material is either acid or base medium.
Find answers for the following questions with the help of your teacher. This will help you to understand how chemistry plays a vital role in our life.
- How does milk change into curd?
- How can you remove stains on the copper vessels?
- Idli is a little bit hard while we cook by using newly grinded idli dough but it is soft with old dough. Why?
- How does rusting of iron happen?
- Why does white sugar change into black when heating?
We can understand the chemical changes that happen around us by knowing the answers for the above questions. We use chemical changes in various forms in our daily life.
Chemistry is the branch of science which deals with the study of particles around us. The beauty of chemistry is that it explains the properties of the basic components of particles such as atoms and molecules and the effects of their combination. We can consider all the particles around us as chemicals. The water (H2O) we drink is the combination of hydrogen and oxygen. The salt (sodium chloride) we use in our kitchen is a combination of the chemicals, sodium and chlorine. Even our body is made up of a lot of chemical particles.
Do You Know?
When we cut onion, we get tears in the eyes with irritation, because of the presence of a chemical, propane thial s-oxide in onion. This is easily volatile. When we cut onion some of the cells are damaged and this chemical comes out. It becomes vapour and reach our eyes result in irritation and tears in eyes. When we crush the onion, more cells will be damaged and more chemicals come out. Why the tears are less produced when onion is cut after soaking in water?
We could prepare soft idly as a result of a chemical change named fermentation that takes place in the idly batter. During fermentation the idly batter undergoes a chemical change by bacteria. While cooking, the food products undergo so many chemical changes. As a result, there are favourable changes in colour, flavour and taste in the food.
We can use chemical changes to produce certain materials. For example, some of the objects such as soaps, fertilizers, plastics and cement which we use in our daily life can be prepared by making chemical changes in some naturally occurring objects
Activity 1
Discuss with your group and list out a few chemicals which we use in our home and school.
We can study about the manufacturing processes and usages of certain materials We use in our daily life such as soaps, fertilizers, cement, gypsum, Epsom, plaster of paris, phenol and adhesives in this lesson.
3.1 Soaps and Detergents
Bathing soap and washing detergents are kinds of soaps which we use in our daily life. In addition to this, we are using washing powder to remove strong stains on the clothes. The detergent molecules have two sides, one side water loving, other water hating. Water hating goes and joins with dirt and oil in the cloth while the water loving joins with the water molecules. When you agitate the cloth, the dirt is surrounded by many molecules and is taken away from the cloth. The cloth becomes clean, and the dirt surrounded by the detergent molecules flat in the water making it dirty.
We can prepare our own soap by the following activity
Activity 2: Preparation of Soap
Materials Required:
- 35 ml of water
- 10 gram of Lye (Sodium hydroxide)
- 60 ml of coconut oil
Process:
- Cover your work area with old newspapers.
- Take 35 ml of water in a jar.
- Add 10 gram of concentrated sodium hydroxide and allow it to cool.
- Then add 60 ml of coconut oil drop by drop and stir it well.
- Pour that solution into an empty match box, soap can be obtained after getting dried.
- Try this soap to wash your handkerchief.
Different soaps for different purposes are prepared with various raw materials. We can understand this by doing the following activity.
Activity 3
Collect various kinds of soap's wrapper. Complete the following table based on the information provided in the wrapper.
| Serial Number | Name of the soap | Ingredients |
|---|
| 1 | Bathing soap | |
| 2 | Washing soap | |
| 3 | Bathing soap for kids | |
| 4 | Toilet Cleaners | |
| 5 | House floor cleaners liquid | |
Inference: Nature of the soaps varies according to its constituents.
3.2 Fertilizers
Apart from water, sunlight and air, certain nutrients are also needed for the growth of plants. We know that the plants get their nutrients from the soil. Nitrogen (N), Phosphorous (P) and Potassium (K) are the three important nutrients among the various nutrients needed for the growth of plants. These three are called Principal Nutrients.
The table given below depicts the quantity of elements absorbed by certain common plants.
| Crop | Approximate Yield per hectare in kilograms | Nitrogen in kilograms | Phosphorus in kilograms | Potassium in kilograms |
|---|
| Rice | 2,240 | 34 | 22 | 67 |
| Corn | 2,016 | 36 | 20 | 39 |
| Sugarcane | 67,200 | 90 | 17 | 202 |
| Groundnut | 1,904 | 78 | 22 | 45 |
What would happen to the nutrient content of the soil, if the field is farmed continuously?
How could we resend these nutrients back to the soil?
Fertilizers are organic or inorganic materials that we add to the soil to provide one or more nutrients to the soil. Fertilizers given to plants can be classified into two. They are organic and in organic fertilizers.
Organic fertilizers
Fertilizers containing only plant or animal-based materials or those synthesized by microorganisms are called organic fertilizers. These fertilizers can be prepared easily. This type of fertilizers are economical. example Vermicompost, compost.
Inorganic fertilizers
The fertilizers prepared by using natural elements by making them undergo chemical changes in the factories are called inorganic fertilizers. example Urea, Ammonium sulphate and Super phosphate and potassium nitrate.
The table given below lists the nutrients in inorganic fertilizers
| Name of the fertilizer | Nitrogen in percentage | Phosphorus in percentage | Potassium in percentage |
|---|
| Urea | 46 | 0 | 0 |
| Super phosphate | 0 | 8 TO 9 | 0 |
| Ammonium sulphate | 21 | 0 | 0 |
| Potassium nitrate | 13 | 0 | 44 |
If we use 50 kg of urea, then according to the table, 23 kg of nitrogen (46 percent) will be added to the soil.
The percentage of nitrogen in ammonium sulphate is
If 50 kg of potassium nitrate is added to soil, how much potassium would the soil get?
Activity 4
Make a visit to the agriculture field in your area. List out the various crops and types of fertilizers used there.
| Serial Number | Name of the crop | Name of the fertilizer |
|---|
| 1 | | |
| 2 | | |
| 3 | | |
Do You Know?
Earthworms take organic wastes as food and produce compost castings. So earthworms are known as Farmer's friends because of the multitude of services they provide to improve soil health and consequently plant health.
3.3 Cement
In the ancient period, the houses were constructed by using the mixture of lime, sand and wood. At present, the people widely use cement for construction of houses, dams and bridges. The cement is manufactured by crushing naturally occurring minerals such as lime, clay and gypsum through a milling process. Cement becomes hardened when it is mixed with water. Gypsum plays a very important role in controlling the rate of hardening of the cement. During the cement manufacturing process, a small amount of gypsum is added at the final grinding process. Gypsum is added to control the "setting of cement".
Do You Know?
In 1824, Joseph Aspdin invented Portland cement by burning finely ground chalk and clay in a kiln. It was named "Portland" cement because it resembled the high-quality building stones found in Portland, England.
Uses of cement
Cement is used as mortar, concrete and reinforced cement concrete.
Mortar
Mortar is a paste of cement and sand mixed with water. In houses, mortar is used to bind building blocks for constructing walls, to apply coating over them and to lay floor.
Concrete
Concrete is a mixture of cement, sand and gravel. It is used in the construction of buildings, bridges and dams.
Reinforced Cement Concrete
Reinforced cement concrete is a composite material by mixing iron mesh with cement. This is very strong and firm. It is used in the construction of dams, bridges, centering works in houses and construction of pillars. Huge water tanks, water pipes and drainages are built with this.
Activity 5
Take three empty tumblers of the same size and name them as A, B and C. Add two teaspoonful of cement in each of the containers. Then pour one teaspoonful of water in container A and two spoon ful of water in B and three spoonful of water in C. After an hour, observe which container of the cement set fast? Touch the containers and see if they are warm or cool. From this experiment, we understand that water and cement should be mixed in a certain ratio for a fast setting.
3.4 Gypsum
Gypsum is a soft white or grey, naturally available mineral. The chemical name of gypsum is calcium sulphate dihydrate. The molecular formula of gypsum is CaSO4 · 2H2O.
Uses
- Used as fertilizers.
- Used in the process of making cement.
- In the process of making Plaster of Paris.
3.5 Epsom
Epsom salt is magnesium sulphate hepta hydrate. The molecular formula of Epsom is MgSO4 · 7H2O. It offers a wide range of uses.
Uses
- Eases stress and relaxes the body
- Helps muscles and nerves function properly
- Medicine for skin problems
- improving plant growth in agriculture
3.6 Plaster of Paris
Plaster of Paris consists of fine white powder (calcium sulphate hemihydrate) The molecular formula of Plaster of Paris is CaSO4 · ½H2O. Known since ancient times, plaster of paris is so called because of its preparation from the abundant gypsum found near Paris, capital of France. Plaster of paris is prepared by heating gypsum, where it gets partially dehydrated.
Uses
- In making black board chalks.
- In surgery for setting fractured bones.
- For making casts for statues and toys etc.
- In construction industry
3.7 Phenol
Have you ever observed the oily material which is used to clean your house? Do you know what it is? It is a chemical, named as Phenol. Phenol is a carbolic acid of an organic compound. It is a necessary ingredient for preparing a variety of phenol products. The molecular formula of phenol is C6H5OH, it is a weak acid. It is a volatile, white crystalline powder. It is a colourless solution, but changes into red in the presence of dust. It irritates when exposed on human skin. It is widely used for industrial purposes. Phenol itself is used (in low concentrations) in mouthwash and as a disinfectant in household cleaners. Phenol is used as a surgical antiseptic since it kills microorganisms.
3.8 Adhesives
What will you do when a page of your book is torn accidentally? It can be fixed by using a cello tape. How does Sellotape work? There is a paste-like material on one surface of the cello tape. Have you ever discussed this material? The paste like substance is called adhesive. It is commonly known as glue, mucilage, or paste. The substances applied to one surface, or both the surfaces of two separate items that binds them together and resists their separation are called adhesives. Adhesives are substances that are used to join two or more components together through attractive forces acting across the Interfaces.
A practical experience
Do you notice how the puncture of your bicycle is repaired by the shopkeeper? He ensures the punctured surfaces are clean, dry and free of dust, and roughens the area around the hole using a metal scraper. He takes an appropriate patch of tyre-tube and applies a suitable adhesive to both the roughened area and to the underside of the patch, applying firm pressure and allows drying completely. Why does he apply pressure? This increases the adhesive capacity at both the surfaces and ensures proper binding.
Types of adhesives
There are two kinds of adhesives, one is natural made from starch and another one is artificial made from chemicals. The one used in a puncture shop is an artificial adhesive. Artificial adhesives may be classified in a variety of ways depending on their utilities. Their forms are paste, liquid, film, pellets, tape. It is used in various conditions such as hot melt, reactive hot melt, thermo setting, pressure sensitive, and contact.
Points to Remember
- Soaps are prepared by heating the mixture of olive oil, animal fat and concentrated sodium hydroxide solutions.
- Fertilizer facilitates growth of plants.
- Vermicompost has high nutrient benefits and it is useful for sustaining the land fertility.
- Cement is manufactured by using lime, clay and gypsum.
- Plaster of Paris is used to fix bone fractures.
- Diluted phenol is used as a cleaner, disinfectant and mouthwash.
- Adhesives are substances that are used to join two or more components together.
ICT Corner
Nutrients for life
Through this activity you will be able to learn about the 4Rs of crop nutrients and their importance.
Step 1: Type the following URL in the browser. 'NUTRIENTS FOR LIFE' activity page will open.
Step 2: Click the 'X' icon on the top left of the activity window to close the welcome note and start the activity or click on 'Next' on the bottom to read the instructions.
Step 3: A com field, 4 cubes and 4 dials are shown, Using the mouse grab the cubes at the bottom which are labelled WATER, N, P, K and drop them over the crop.
Step 4: Each time you apply water or nutrients on the crop it will rise the dial. Keep all the dials in the green. Repeat the same process till the crop is fully grown.
Nutrients for life URL: http://seedsurvivor.com/agrium-games/Feeding%20the%20Future/
pictures are indicative only
Evaluation
Exercise 1. Choose the appropriate answer
1. Soaps were originally made from ______.
a. proteins b. animal fats and vegetable oils c. chemicals extracted from the soil d. foam booster
2. The saponification of a fat or oil is done using ______ solution for hot process.
a. Ammonium hydroxide b. Sodium hydroxide c. Hydrochloric acid d. Sodium chloride
3. Gypsum is added to the cement for ______.
a. fast setting b. delayed setting c. hardening d. making paste
4. Phenol is ______.
a. carbolic acid b. acetic acid c. benzoic acid d. hydrochloric acid
5. Natural adhesives are made from ______.
a. Protein b. fat c. starch d. Vitamins Exercise 2. Fill in the Blanks
1. gas causes tears in our eyes while cutting onions.
2. Water, coconut oil and are necessary for soap preparation.
3. is called a farmer's best friend.
4. fertilizer is eco-friendly.
5. is an example for natural adhesive.
Exercise 3. True or False. If False, give the correct statement 1. Concentrated phenol is used as a disinfectant. 2. Gypsum is largely used in medical industries. 3. Plaster of Paris is obtained from heating gypsum. 4. Adhesives are the substances used to separate the components. 5. N P K are the primary nutrients for plants. Exercise 4. Match the following
| 1. Soap | |
| 2. Cement | |
| 3. Fertilizers | |
| 4. Gypsum | |
| 5. Phenol | |
Options: C6H5OH, CALCIUM SULPHATE 2H2O, sodium hydroxide, RCC, NPK
Exercise 5. Arrange the following statements in correct sequence Pour that solution into an empty match box, soap can be obtained after drying. Take the necessary quantity of water in a jar. Then add coconut oil drop by drop and stir it well. Add concentrated sodium hydroxide in the jar and allow it to cool. Try this soap to wash your hand kerchief. Cover your work area with old newspapers. Exercise 6. Analogy
1. Urea: Inorganic fertilizer: Vermicompost:
2. STARCH: Natural adhesives: Cello tape:
Exercise 7. Give very short answer
1. What are the three main constituents of soap?
2. What are the two different types of molecules found in the soap?
3. Give an example for inorganic fertilizer.
4. Mention any three physical properties of phenol.
5. Explain the uses of plaster of paris.
6. What are the ingredients of the cement?
7. Why is gypsum used in cement production?
Exercise 8. Give short answer
1. Why is an earthworm called a farmer's friend?
2. Explain the process of manufacturing cement.
3. What are the uses of Gypsum?
Exercise 9. Answer in detail
1. Explain what is RCC and give its uses?
2. How are detergents manufactured?
Exercise 10. Questions based on Higher Order Thinking Skills
1. Ravi is a farmer; he rears many cattle in his farm. His field has many bio wastes. Advise Ravi how to change this bio waste to compost by using vermicomposting techniques. Explain the benefits of vermi castings.
Exercise 11. Project
Take 100 ml of hot water in a glass jar. Add 50 gram of maida in the hot water and stir it well. A paste-like substance is formed. Add a small quantity of copper sulphate for a long use. Now you test this paste by binding your damaged book.
📝 Summary
- Chemistry plays a vital role in everyday life, with chemical changes occurring all around us - from cooking food to preparing materials like soaps and fertilizers.
- Chemical changes result in the formation of new substances (like burning paper into ash), while physical changes only alter shape, size, or state without changing the substance itself.
- Turmeric powder acts as a natural indicator that changes color when mixed with different household liquids, helping identify whether a substance is acidic or basic.
- Common everyday processes involve chemical changes, such as milk turning into curd, fermentation making soft idli, rusting of iron, and sugar turning black when heated.
- All particles around us are essentially chemicals - water is a combination of hydrogen and oxygen, salt combines sodium and chlorine, and even our bodies are made up of chemical particles.