Question

The diagram shows an apparatus for the laboratory preparation of hydrogen chloride.
(i) Identify A and B.
(ii) Write the equation for the reaction.
(iii) How would you check whether or not the gas jar is filled with hydrogen chloride?
(iv) What does the method of collection tell you about the density of hydrogen chloride?

Answer 1

(i) The given image represents the laboratory preparation of hydrochloric acid. In the given figure, A and B denote concentrated sulphuric acid and sodium chloride, respectively.

(ii) The reaction takes place as follows:

NaCl + H₂SO₄ → NaHSO₄ + HCl (g)
Sodium chloride Sulphuric acid Sodium hydrogen Hydrogen chloride
sulphate gas

(iii) When a glass rod dipped in ammonia solution is brought near the mouth of a gas jar, dense white fumes are formed. This confirms the presence of HCl gas in the glass jar.

HCl (g) + NH₃ (aq) → NH₄Cl (s)

(iv) HCl gas is collected by the upward displacement of air. This concludes that HCl gas is heavier than air or density of HCl gas is more than that of air..