Question

(i)Dry pellets of a base 'X' when kept in open absorbs moisture and turns sticky.
The compound is also formed by chlor-alkali process. Write chemical name and
formula of X. Describe chlor-alkali process with balanced chemical equation.
Name the type of reaction occurs when X is treated with dilute hydrochloric acid.
Write the chemical equation.

(ii) While diluting an acid, why is it recommended that the acid should be added to
water and not water to the acid ?
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Answer 1

Answer:

(i) ✎ X is NaOH (Sodium hydroxide)

✎ Chlor - alkali process : On passing electricity through an aqueous solution of sodium chloride(brine) it decomposes to form sodium hydroxide. This process is called chlor - alkali process because of the products formed. Chlor for chlorine and alkali for sodium hydroxide.

Reaction :-

$\rm{2NaCl+2H_2O\longrightarrow{}2NaOH+Cl_2+H_2}$

✎ The type of reaction between X and dil. HCl acid is a neutralization reaction(Acid + Base → salt + water).

Reaction :-

$\rm{NaOH+HCl\longrightarrow{}NaCl+H_2O}$

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(ii) ✎ The process of mixing an acid or base with water is a highly exothermic (heat releasing) one. During dilution, acid should be added slowly to water with constant stirring. If water is added to a concentrated acid, the exothermic process will take up a violent form and the heat generated may cause the mixture to splash out and cause severe skin burns.