Question

\[{\text{NaCl}}\,\,{\text{ + }}\,{{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_4}\, \to \,{\text{NaHS}}{{\text{O}}_{\text{4}}}{\text{ + }}\,{\text{HCl}}\]
This reaction occurs when temperature is:
A. Less than $200{^ \circ }{\text{C}}$
B. More than $200{^ \circ }{\text{C}}$
C. Less than $200{^ \circ }{\text{C}}$
D. None of the above

Answer 1

Hint: The reaction of metal chloride and sulphuric acid produce hydrochloric gas as a by-product. The reaction occurs at a low or normal temperature.

Complete answer:
The metal chloride reacts with concentrated sulphuric acid produces hydrochloric gas as a by-product.
Here, the metal chloride is sodium chloride.
When sodium chloride is mixed with sulphuric acid, no reaction occurs.
When solid sodium chloride is heated with concentrated sulphuric acid in the temperature range $30 - 40{\,^ \circ }{\text{C}}$ , the products sodium bisulphate and hydrogen chloride form.
\[{\text{NaCl}}\,\,{\text{ + }}\,{{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_4}\, \xrightarrow{< \,200^\circ} \,{\text{NaHS}}{{\text{O}}_{\text{4}}}{\text{ + }}\,{\text{HCl}}\]
So, the reaction occurs in the range of $30 - 40{^ \circ }{\text{C}}$ temperature, so option (A) is correct.
The reaction does not occur above $200{^ \circ }{\text{C}}$ temperature, so option (B) is incorrect.
The reaction does not occur at $200{^ \circ }{\text{C}}$ temperature, so option (C) is incorrect.

So the correct answer is (A).

Additional Information: Hydrochloric acid is also known as hydronium chloride. The common name of hydrochloric acid is muriatic acid. It is a strong acid. Hydrochloric acid is also present in the digestive juice of the human stomach.
The hydrochloric acid is formed by the reaction of hydrogen gas with chlorine gas in presence of sunlight. The reaction is as follows:
\[{{\text{H}}_{\text{2}}}(g)\,{\text{ + }}\,{\text{C}}{{\text{l}}_{\text{2}}}(g)\,\mathop \to \limits^{{\text{sunlight}}} \,{\text{2HCl}}\,\,(g)\]
This hydrogen chloride gas is dissolved into water to form hydrochloric acid.

Note: The reaction is mainly used for the preparation of hydrochloric acid. The boiling point of the hydrochloric acid is $108{^ \circ }{\text{C}}$ so, at $200{^ \circ }{\text{C}}$ temperature or above it, the liquid will be volatile so, it cannot be prepared at $200{^ \circ }{\text{C}}$ temperature or above it.