Question

A more reactive metal displaces a less reactive metal from the aqueous solution. From the following set tell which one represents a correct picture, of both the possible ($\mathbf{Y}$) reaction and impossible ($\mathbf{N}$) reactions between metals and the solution of different salts.

• A.

  Metal	${Al}_2{\left({SO}_4\right)}_2$	${CuSO}_4$	${FeSO}_4$	${ZnSO}_4$
  $Al$	$N$	$Y$	$Y$	$Y$

• B.

  Metal	${Al}_2{\left({SO}_4\right)}_2$	${CuSO}_4$	${FeSO}_4$	${ZnSO}_4$
  $Cu$	$Y$	$N$	$N$	$N$

• C.

  Metal	${Al}_2{\left({SO}_4\right)}_2$	${CuSO}_4$	${FeSO}_4$	${ZnSO}_4$
  $Fe$	$Y$	$Y$	$N$	$N$

• D.

  Metal	${Al}_2{\left({SO}_4\right)}_2$	${CuSO}_4$	${FeSO}_4$	${ZnSO}_4$
  $Zn$	$N$	$Y$	$N$	$Y$

Answer 1

The correct option is A

Metal	${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_2$	${\mathrm{CuSO}}_4$	${\mathrm{FeSO}}_4$	${\mathrm{ZnSO}}_4$
$\mathrm{Al}$	$\mathbf{N}$	$\mathbf{Y}$	$\mathbf{Y}$	$\mathbf{Y}$

The explanation for the correct answer.

Option A

Case(I)

• When Aluminium Sulphate is added to Aluminium no change will be observed as both metals are the same, i.e.Aluminium
• $$\begin{gathered} \mathbf{Al}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{Al}}_{\mathbf{2}}{\mathbf{\left(}{\mathbf{SO}}_{\mathbf{4}}\mathbf{\right)}}_{\mathbf{3}}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{No}\mathbf{}\mathbf{reaction} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Aluminium}\mathbf{}\mathbf{Sulphate} \end{gathered}$$
• Hence, no reaction takes place.

Case (II)

• When Copper Sulphate solution is added to the Aluminium, Aluminum displaces Copper from the Copper Sulphate solution because Aluminium is more reactive than Copper.
• $$\begin{gathered} \mathbf{2}\mathbf{}\mathbf{Al}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{3}\mathbf{}{\mathbf{CuSO}}_{\mathbf{4}}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}{\mathbf{Al}}_{\mathbf{2}}{\mathbf{\left(}{\mathbf{SO}}_{\mathbf{4}}\mathbf{\right)}}_{\mathbf{3}}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{3}\mathbf{}\mathbf{Cu}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Iron}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Aluminium}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Sulphate}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Sulphate} \end{gathered}$$

Case (III)

• When Iron Sulphate solution is added to the Aluminium, Aluminum displaces iron from the Iron Sulphate solution because Aluminium is more reactive than Iron. So the green colour of ${\mathbf{FeSO}}_{\mathbf{4}}$ disappears.
• $$\begin{gathered} \mathbf{2}\mathbf{}\mathbf{Al}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{3}\mathbf{}{\mathbf{FeSO}}_{\mathbf{4}}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}{\mathbf{Al}}_{\mathbf{2}}{\mathbf{\left(}{\mathbf{SO}}_{\mathbf{4}}\mathbf{\right)}}_{\mathbf{3}}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{3}\mathbf{}\mathbf{Fe}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Iron}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Aluminium}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Sulphate}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Sulphate} \end{gathered}$$

Case (IV)

• When Zinc Sulphate is added to the Aluminium, then Aluminium displaces Zinc from the Zinc Sulphate solution because Aluminium is more reactive than Zinc.
• $$\begin{gathered} \mathbf{2}\mathbf{}\mathbf{Al}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{3}\mathbf{}{\mathbf{ZnSO}}_{\mathbf{4}}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}{\mathbf{Al}}_{\mathbf{2}}{\left({\mathrm{SO}}_4\right)}_{\mathbf{3}}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{}\mathbf{3}\mathbf{}\mathbf{Zn}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Zinc}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Aluminium}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Sulphate}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Sulphate} \end{gathered}$$
• Copper, Iron and Zinc are placed below Aluminium in the reactivity series, hence these are possible reactions.
• Aluminium can not react with Aluminium Sulphate (${\mathbf{Al}}_{\mathbf{2}}{\mathbf{\left(}{\mathbf{SO}}_{\mathbf{4}}\mathbf{\right)}}_{\mathbf{2}}$), hence it is an impossible reaction
• Hence option (A) is correct.