Question

Which chemicals are used to carry out the following actions?
i) To make drinking water free of germs
ii) To make tasty, crispy pakoras in the kitchen
iii) To remove permanent hardness of water
iv) To make toys and decorative materials

Answer 1

Hint: Think about what exactly occurs chemically during each of the processes mentioned in the options. Consider the best chemical that will carry out the given tasks in an efficient manner.

Complete step by step answer:
We will look at each of the options given one by one to determine which chemicals are used for the enlisted actions.
i) To make drinking water free of germs
To make drinking water free of germs, we usually add chemicals to it that will kill of all the germs present by making the environment toxic for them. We have seen the chemical ‘chlorine’ added to swimming pools and have noticed its distinctive smell. This chlorine is used to make drinking water potable as well but the quantity required to do this is not as much as is required in swimming pools. So, the chemical that makes water free of germs most effectively is chlorine.

ii) To make tasty, crispy pakoras in the kitchen
To make tasty crispy pakoras, some carbon dioxide needs to be released while the cooking occurs as the pakoras need to be crispy and airy despite all the oil. This release of $C{{O}_{2}}$ while cooking can be achieved by adding baking soda to the batter of the pakoras. The chemical formula of baking soda is $NaHC{{O}_{3}}$. We can also add baking soda to cakes to make them tastier. So, the chemical used during this process is baking soda.

iii) To remove permanent hardness of water
The permanent hardness occurs due to the presence of calcium and magnesium sulphates and phosphates. These reduce the cleaning capacity of soap by forming a white layer that has no cleaning properties called scum. These ions need to be precipitated out of the water. Carbonate compounds of calcium and magnesium are insoluble in water. A chemical called washing soda is used to remove this permanent hardness of water. The chemical formula of washing soda is $N{{a}_{2}}C{{O}_{3}}$.

iv) To make toys and decorative materials
There are actually many materials and chemicals that can be used to make toys as well as decorative articles. But the most common out of them are plastics and synthetic materials. We see that a lot of toys and decorative articles are made of different types of plastics. So, the chemical used in these processes is plastic

Note: The common names for baking soda and washing soda are sodium bicarbonate and sodium carbonate respectively. To remember these names, it will help to remember that baking and bicarbonate both start with a B.
In earlier times, plaster of paris was also a material that was used to make toys and decorative articles, but today, the widespread use of plastic is seen.