Question

Hydrogen can be obtained from displacement from:
(i) dilute hydrochloric acid
(ii) dilute sulphuric acid.
Justify your answer by writing balanced chemical equations with zinc.
Why copper metals does not show similar behaviour with these acids?

Answer 1

(ii) Diluted Sulphuric Acid

Explanation:

Hydrogen can be obtained by displacement from diluted sulphuric acid.

Zn + H2SO4 ----> H2 + ZnSO2

Zinc reacts with H2SO4 to form Zinc Sulphate and hydrogen gas is also liberated. This happens beacause zinc is more reactive than hydrogen. This is a displacement reaction. But copper does not react with H2SO4 as copper is less reactive than hydrogen.

Option II is the correct answer.

Answer 2

Answer:

(a) Zinc and iron lie above hydrogen in reactivity series and can displace hydrogen from acid.

Zn + H2SO4 → ZnSO4 + H2 ↑

(dilute)

Fe + H2SO4 → FeSO4 + H2 ↑

(dilute)

(b) Zn + 2HCl → ZnCl2 + H2 ↑

(dilute)

Fe + 2HCl → FeCl2 + H2 ↑

(dilute)

Copper lies below hydrogen. Thus, it cannot displace hydrogen from acids