Question

In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as by-product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.

October 1, 2024

Answer

In the industrial process for manufacturing sodium hydroxide (NaOH), the gas X formed as a by-product is chlorine gas (Cl₂). When chlorine gas reacts with lime water (which is a solution of calcium hydroxide, Ca(OH)₂), it forms calcium hypochlorite (Ca(OCl)₂), which is the compound Y used as a bleaching agent.

The reactions can be represented by the following chemical equations:

1. Formation of chlorine gas (X):

2NaCl + 2H2O → Cl2 + H2 + 2NaOH

(This reaction shows the production of chlorine gas while making sodium hydroxide.)

2. Reaction of chlorine gas with lime water:

Cl2 + Ca(OH)2 → Ca(OCl)2 + H2O

(This reaction shows chlorine gas reacting with lime water to form calcium hypochlorite, the bleaching powder.)

So, in summary:

– Gas X: Chlorine (Cl₂)

– Compound Y: Calcium hypochlorite (Ca(OCl)₂)

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