Chemistry in Everyday life
• 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
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 Physical change
• burning of a paper Chemical change
• tearing paper into small pieces Physical change
• dissolving of sugar in water Physical change
• burning of petrol or LPG gas Chemical change
• water boiling into water vapour Physical change
• coconut oil becoming solid during winter Physical change
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 is mixed with the air.
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 answer for the following questions with the help of your teacher. This will help you to understand how chemistry plays vital role in our life.
• How does milk change into curd?
• How can you remove stain 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 (NaCl) 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.
When we cut onion, we get tears in the eyes with irritation, because of the presence of a chemical, propanethial 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.
We could prepare soft idly as a result of a chemical change named fermentation 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 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.