ICSE Class 9 Chemistry Question 23 of 26

Study of the First Element — Hydrogen — Question 24

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Question

Question 3(1993)

Account for the following facts :

(i) Though lead is above hydrogen in the activity series, it does not react with dilute hydrochloric acid or dilute sulphuric acid.

(ii) Potassium and sodium are not used to react with dilute hydrochloric acid or dilute sulphuric acid in the laboratory preparation of hydrogen.

Answer

(i) Lead reacts with dilute hydrochloric acid or dilute sulphuric acid forming an insoluble coating of lead chloride (PbCl2) and lead sulphate (PbSO4) respectively, hence, stops the further reaction.

(ii) Potassium and sodium are not used to react with dilute hydrochloric acid or dilute sulphuric acid in the laboratory preparation of hydrogen because the reaction is highly explosive and practically not-feasible.