Question

When iron is added to $CuS{O_4}$solution, copper is precipitated . It is due to :
A.oxidation of $C{u^{ + 2}}$
B.reduction of $C{u^{ + 2}}$
C.hydrolysis of $CuS{O_4}$
D.ionization of $CuS{O_4}$

Answer 1

Hint: We know that when iron is added in $CuS{O_4}$solution , copper is precipitated . The reaction between iron and $CuS{O_4}$is an example of redox reaction . That is it undergoes both oxidation and reduction reaction simultaneously .

Complete step by step solution:
The chemical reaction between $CuS{O_4}$solution and iron can be written as : $Fe + CuS{O_4} \to Fe(S{O_4}) + Cu$. Now we will write the chemical reaction by denoting their respective oxidation states: $F{e^0} + C{u^{II}}SO{}_4 \to F{e^{II}}(S{O_4}) + C{u^0}$. We can observe that The oxidation number of $Fe$ is changing from $0$ to $2$. The oxidation number is increasing , that means it is undergoing oxidation. Similarly the oxidation state of $Cu$ is changing from $2$ to $0$. The oxidation number is decreasing , that means $C{u^{ + 2}}$ is undergoing a reduction reaction.

Hence, option: B. reduction of $C{u^{ + 2}}$ is correct.

Additional information: $CuS{O_4}$ is also known as blue vitriol (pentahydrate).In the reaction $Fe + CuS{O_4} \to Fe(S{O_4}) + Cu$ ,$CuS{O_4}$ is an oxidising agent and $Fe$is a reducing agent. $CuS{O_4}$ can kill bacteria, algae, roots, plants ,snails and fungi. Copper sulphate can be toxic. The toxicity depends on the copper content. The anhydrous copper sulphate is greenish white in colour .The pentahydrate form is blue in colour. The density of anhydrous copper sulphate is $3.60g/c{m^3}$. An anhydrous compound does not contain water molecules attached to it.

Note:
Always remember that whenever iron is added to $CuS{O_4}$ solution, the reaction we will observe is $F{e^0} + C{u^{II}}SO{}_4 \to F{e^{II}}(S{O_4}) + C{u^0}$. Copper ions get reduced and get precipitated. The iron gets oxidised from $Fe$to $F{e^{II}}$.In this reaction $CuS{O_4}$is an oxidising agent and $Fe$ is a reducing agent.