Question 14 Marks
Redox reactions are those reactions in which oxidation and reduction occur simultaneously. A redox reaction is made up of two half reactions. In the first half reaction, oxidation takes place and in second half reaction, reduction occurs. Oxidation is a process in which a substance loses electrons and in reduction, a substance gains electrons. The substance which gains electrons is reduced and acts as an oxidising agent. On the other hand, a substance which loses electrons is oxidised and acts as a reducing agent.
i. Illustrate where oxidation and reduction occurs together with an example?
ii. What do you mean by oxidising agent and reducing agent?
iii. For the given reaction, identify the oxidation and reduction parts.
$ZnO + CO \longrightarrow Zn + CO _2$
OR
In the following reaction, which substance is reduced?
$\mathrm{PbS}+4 \mathrm{H}_{2} \mathrm{O}_{2} \longrightarrow \mathrm{PbSO}_{4}+4 \mathrm{H}_{2} \mathrm{O}$
i. Illustrate where oxidation and reduction occurs together with an example?
ii. What do you mean by oxidising agent and reducing agent?
iii. For the given reaction, identify the oxidation and reduction parts.
$ZnO + CO \longrightarrow Zn + CO _2$
OR
In the following reaction, which substance is reduced?
$\mathrm{PbS}+4 \mathrm{H}_{2} \mathrm{O}_{2} \longrightarrow \mathrm{PbSO}_{4}+4 \mathrm{H}_{2} \mathrm{O}$
Answer
View full question & answer→i. The oxidation and reduction occurring together are called a redox reaction. $\mathrm{CuO}+\mathrm{H}_{2} \longrightarrow \mathrm{Cu}+\mathrm{H}_{2} \mathrm{O}$. Example: In this reaction, copper oxide is being reduced to copper whereas hydrogen is being oxidised to water.
ii. Oxidising agents give oxygen to or removes hydrogen from other substances. The reducing agent undergoes loss of electrons. A reducing agent (also called a reductant or reducer) is an element or compound that loses (or "donates") an electron to another chemical species in a redox chemical reaction.
iii. ZnO is being reduced
ZnO is reduced to Zn and CO is oxidised to $\mathrm{CO}_{2}$
OR
$\mathrm{H}_{2} \mathrm{O}_{2}$ is reduced to water by removal of oxygen.
ii. Oxidising agents give oxygen to or removes hydrogen from other substances. The reducing agent undergoes loss of electrons. A reducing agent (also called a reductant or reducer) is an element or compound that loses (or "donates") an electron to another chemical species in a redox chemical reaction.
iii. ZnO is being reduced
ZnO is reduced to Zn and CO is oxidised to $\mathrm{CO}_{2}$
OR
$\mathrm{H}_{2} \mathrm{O}_{2}$ is reduced to water by removal of oxygen.