Question

Bleaching powder loses its power on keeping for a long time because :
(A) It changes into calcium hypochlorite
(B) It changes into calcium chloride and calcium hydroxide
(C) It absorbs moisture
(D) It changes into calcium chloride and calcium chlorate

Answer 1

Hint: In this question, we will discuss the bleaching powder. First we understand some common properties of bleaching powder, then we discuss what happens when the bleaching powder is exposed to air and why it loses its power after a long time.

Complete Step by Step Solution:
Bleaching powder's chemical formula is CaOCl₂ with a chemical name as Calcium hypochlorite This is a light yellowish powder and has a strong smell of chlorine. If bleaching powder is held exposed in the air, it reacts with carbon dioxide from the atmosphere to produce calcium carbonate $(CaC{{O}_{3}})$ and chlorine gas $(C{{l}_{2}})$
$CaOC{{l}_{2}}+C{{O}_{2}}\to CaC{{O}_{3}}+C{{l}_{2}}$

Calcium carbonate is a food fibre that is used when the calcium contained in the diet is not proper. Calcium is essential for healthy bones, muscles, nervous system and heart. Also, calcium carbonate is used as an antacid to mitigate heartburn, acid indigestion and stomach discomfort. Chlorine is a compound used in making goods for household washing. Chlorine is a gas, at room temperature. It is shown a yellow-green colour, and an unpleasant, pungent smell.

When the bleaching powder is exposed to air for a long time, it undergoes autoxidation into calcium chlorate and calcium chloride and loses its power.
$6CaOC{{l}_{2}}\to 6Ca{{(ClO{}_{3})}_{2}}+5CaC{{l}_{2}}$
Thus, Option (D) is correct.

Note: Bleaching powder has many uses in our daily life. It is used for bleaching dirty clothes in the laundry, and acts as a bleaching agent for cotton and linen in the textile industry. It is used as a purifier which is used for disinfecting water to make fresh water.