Question

A black metal oxide XO₂ is used as a catalyst in the preparation of oxygen gas from potassium chlorate. The oxide XO₂ is also used in ordinary dry cells. The metal oxide XO₂ cannot be reduced satisfactorily with carbon to form metal X.
(a) Name the metal X.
(b) Name the metal oxide XO₂.
(c) Which reducing agent can be used to reduce XO₂ to obtain metal X?
(d) Name another metal which can also be extracted by the reduction of its oxide with the above reducing agent.

Answer 1

(a) Metal X is manganese. 
Manganese dioxide, MnO₂ (black in colour), is used as a catalyst in the preparation of oxygen gas from potassium chlorate. Manganese dioxide is also used in ordinary dry cells. Manganese is a reactive metal; therefore, manganese dioxide cannot be reduced satisfactorily with carbon to form manganese metal. 

(b)The metal oxide is manganese dioxide, MnO₂.

(c) Manganese dioxide, MnO₂, cannot be reduced satisfactorily with carbon to form manganese metal. Manganese is comparatively more reactive; therefore, aluminium is used in place of carbon as a reducing agent.

(d) Iron can also be extracted when aluminium is used as a reducing agent. This reaction is called thermite reaction.In this reaction, iron (III) oxide is reduced by with aluminium powder to give iron and aluminium oxide. This reaction is used for welding broken railway tracks.