Question

In the reaction ${\text{CuO + }}{{\text{H}}_{\text{2}}} \to {\text{Cu + }}{{\text{H}}_{\text{2}}}{\text{O}}$ which substance gets oxidized and which gets reduced? Give one more example of such a reaction.

Answer 1

Hint: The given reaction is a redox reaction or an oxidation – reduction reaction.In a redox reaction, the reducing agent or the reductant gets oxidized while the oxidizing agent or oxidant gets reduced.

Complete step by step answer:
-In redox reactions, the reactants undergo a change in their oxidation states. All the redox reactions involve two processes- a reduction process and an oxidation process. These two processes always occur simultaneously. Thus redox reactions are chemical reactions that involve the transfer of electrons between the reactants taking part in it.
-Now, in the given reaction ${\text{CuO + }}{{\text{H}}_{\text{2}}} \to {\text{Cu + }}{{\text{H}}_{\text{2}}}{\text{O}}$ , copper which is in +2 oxidation state in cupric oxide gains 2 electrons and gets reduced to 0 state in copper atom.
${\text{C}}{{\text{u}}^{{\text{2 + }}}}{\text{ + 2}}{{\text{e}}^{\text{ - }}} \to {\text{C}}{{\text{u}}^{\text{0}}}$
 -On the other hand, hydrogen in 0 state in a hydrogen atom loses 2 electrons and gets oxidized into +1 state in water.
Thus, hydrogen is oxidized and copper is reduced.
-One more example of a redox reaction is the reaction between lead sulfide and hydrogen peroxide. Lead sulfide having the chemical formula ${\text{PbS}}$ reacts with hydrogen peroxide, ${{\text{H}}_{\text{2}}}{{\text{O}}_{\text{2}}}$ to give lead sulphate which has the chemical formula ${\text{PbS}}{{\text{O}}_{\text{4}}}$ and water as products. The balanced chemical equation of the reaction between lead sulfide and hydrogen peroxide is shown below.
${\text{PbS + 4}}{{\text{H}}_{\text{2}}}{{\text{O}}_{\text{2}}} \to {\text{PbS}}{{\text{O}}_4} + {\text{4}}{{\text{H}}_{\text{2}}}{\text{O}}$
Lead sulfide is a black precipitate and lead sulphate is a white precipitate.
-This is a redox reaction in which hydrogen peroxide oxidizes lead sulfide in which sulphur is in -2 oxidation state to lead sulphate in which sulphur is in +6 oxidation state. On the other hand, oxygen of hydrogen peroxide in -1 state is reduced to -2 state in water. Thus, in this redox reaction, hydrogen peroxide acts as the oxidizing agent and lead sulfide acts as the reducing agent.

Note:
Redox reactions have many applications in electrochemistry. Redox reaction is used by the battery used for generating DC current to produce electrical energy.
Storage cells used in vehicles to supply all the electrical needs of vehicles are also based on redox reactions.
The process of photosynthesis is also a redox reaction as carbon dioxide is reduced to carbohydrates and water is oxidized to oxygen.
$6{\text{C}}{{\text{O}}_{\text{2}}}{\text{ + 12}}{{\text{H}}_{\text{2}}}{\text{O + light}} \to {{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}{\text{ + 6}}{{\text{O}}_{\text{2}}}{\text{ + 6}}{{\text{H}}_{\text{2}}}{\text{O}}$