Question

Iron can react with copper sulphate solution to form iron sulphate and copper, but copper cannot react with iron sulphate to form copper sulphate and iron. Explain.

Answer 1

Reactivity series:

• Reactivity series is the arrangement of metals in the decreasing order of their reactivity in a tabular form.
• In the reactivity series, a metal can displace the metals present below that element in the reactivity series.

Reaction of iron with copper:

• Iron is placed above the copper in the reactivity series. So, iron can displace copper from its salt solution.
• Now, Iron $\left(\mathrm{Fe}\right)$ can react with copper sulphate $\left({\mathrm{CuSO}}_4\right)$ solution to form iron sulphate $\left({\mathrm{FeSO}}_4\right)$ and copper $\left(\mathrm{Cu}\right)$.
• This reaction is a type of displacement reaction.
• Displacement reaction: The reaction in which a more reactive element displaces a less reactive element from its compound, is known as a displacement reaction.

Example - $$\begin{gathered} \mathrm{Fe}\left(\mathrm{s}\right)+{\mathrm{CuSO}}_4\left(\mathrm{aq}\right)\stackrel{}{\to }{\mathrm{FeSO}}_4\left(\mathrm{aq}\right)+\mathrm{Cu}\left(\mathrm{s}\right) \\ (\mathrm{blue}\mathrm{colour})(\mathrm{green}\mathrm{colour}) \end{gathered}$$

• But copper cannot react with iron sulphate to form copper sulphate and iron because copper cannot displace iron from its solution as copper is less reactive than iron.

$\mathrm{Cu}\left(\mathrm{s}\right)+{\mathrm{FeSO}}_4\left(\mathrm{aq}\right)\stackrel{}{\to }\mathrm{No}\mathrm{reaction}$