Answer to Question #285515 in General Chemistry for Nonny

Question

Suggest why barium reacts with dilute hydrochloric acid but appears not to react with dilute sulphuric acid.

Answer 1

Solution:

H₂SO₄ reacts with Ba forming BaSO₄ which is insoluble, so it forms a thin layer on the metal's surface, preventing a further action of the acid.

In the case of the reaction of barium chloride with dilute hydrochloric acid, the double displacement reaction cannot take place due to the same anions with both the reactants.

$$BaCl_2(aq)+HCl(aq) \implies no \;reaction$$

BaCl₂ (aq.)+ HCl (aq.) ----- > no reaction

The reaction of barium chloride with dilute sulphuric acid forms a white precipitate of barium sulphate and hydrochloric acid. This type of reaction is called a double displacement reaction in which both the reactants exchange their partners.

$$BaCl_2(aq)+H_2SO_4(aq) \implies BaSO_4(s)+2HCl(aq)$$

For a reaction to take place, either of the following conditions which must take place:

(a) the formation of insoluble product or precipitate.

(b) the evolution of gas.

(c) the formation of non-dissociating product.

Neither of these conditions is taking place on the reaction of barium chloride with dilute hydrochloric acid hence, no reaction takes place in either of these cases contrary to that of dilute sulphuric acid.