Question

Name the type of following chemical reaction.
\[CuO+{{H}_{2}}\to Cu+{{H}_{2}}O\]
(A) Combination
(B) Displacement
(C) Decomposition
(D) Neutralisation

Answer 1

Hint: In combination reaction two reactants combine and form the product. Example \[Fe+S\to FeS\]. In displacement reaction, the more reactive element displaces the less reactive element and forms the product. Example \[CuS{{O}_{4}}+Fe\to Cu+FeS{{O}_{4}}\]. The decomposition reaction is the reaction in which two or more products are formed from one reactant. Example \[2{{H}_{2}}O\to 2{{H}_{2}}+{{O}_{2}}\]. Neutralisation reaction is the reaction in which acid and base react together to form salt and water. Example \[HCl+NaOH\to NaCl+{{H}_{2}}O\]

Complete answer:
In the above reaction the copper oxide is converting to copper and hydrogen is converting to water. So the oxygen is being displaced from copper to hydrogen in the given reaction. Hence this is a displacement reaction because one element is being displaced from the compound. So the correct option for this question is option ‘b’. In this reaction the oxidizing agent is copper oxide because oxygen is being removed from copper oxide in the reactant and converted into copper in product, this shows loss of oxygen. The oxidized substance is water and the reduced substance is copper. This reaction is a redox reaction also because in this both oxidation and reduction is happening. Oxidation means loss of electrons or when oxygen is combined with the element thus changing its appearance in reaction. Hydrogen changing to water is oxidation. Reduction means gain of electrons or when oxygen is reduced from the element thereby changing its appearance in reaction. Here copper oxide is being changed to copper is a reduction reaction.

Hence the correct option is B.

Note: The one more type of displacement reaction is double displacement reaction. In this reaction the reactant ions interchange their positions to form new reactants .The product formed by double displacement reaction is generally a product. Example \[CuC{{l}_{2}}(aq)+2AgN{{O}_{3}}(aq)\to Cu{{(N{{O}_{3}})}_{2}}(aq)+2AgCl(s)\]]