Q34 of 45 Page 2

(a) Identify the compound of calcium which is yellowish white powder and is used for disinfecting drinking water. Write its chemical name and formula. How is it manufactured? Write the chemical equation for the reaction involved. Also, list two other uses of the compound.

(b) Write the balanced chemical equation of chlor-alkali process.

(a) The compound of calcium which is a yellowish white powder and is used for disinfecting drinking water is CaOCl2 commonly known as bleaching powder.

Its chemical name is – Calcium oxychloride


Formula - CaOCl2

Formation of bleaching powder.

When chlorine gas is allowed to pass through the slaked lime solution leads to the formation of bleaching powder.
The chemical equation for the reaction involved is: -

Ca(OH)2 + Cl2→ CaOCl2 + H2O

Two other uses of the compound are:-

1. It is used as an oxidising agent in many chemical industries.

2. It is used for bleaching cotton and linen in the textile industry, wood pulp bleaching and for bleaching washed clothes in the laundry.


(b) The balanced chemical equation of chlor-alkali process is : -


2NaCl (aq) +2H2O (l) → 2NaOH (aq) + Cl2 (g) + H2 (g)

More from this chapter

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31

Explain the following chemical properties of acids with the help of balanced chemical equations only.

(i) when an acid reacts with a metal carbonate


(ii) when an acid reacts with a metal bicarbonate


(iii) when an acid reacts with a metal oxide

 32

In the following schematic diagram for the preparation of hydrogen gas as shown in the given figure, what would happen if the following changes are made?


(a) In place of zinc granules, same amount of zinc dust is taken in the test tube.


(b) Instead of dilute sulphuric acid, dilute hydrochloric acid is taken.


(c) In place of zinc, copper turnings are taken.


(d) Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.

 33

(a) Identify the acid and the base whose combination forms the common salt that you use in your food. Write its formula and chemical name of this slat. Name the source from where it is obtained.

(b) What is rock salt? Mention its colour and the reason due to which it has this colour.


(c) What happens when electricity is passed through brine? Write the chemical equation for it.

 35

(a) Crystals of a substance changed their colour on heating in a closed test tube but regained it after sometime when they were allowed to cool down. Name the substance and write its formula and explain the phenomenon involved.

(b) Name the compound whose one formula unit is associated with 10 water molecules. How is it prepared? Give equations of related reactions. Give two uses of the compound.