Question

What takes place when zinc metal is added to an aqueous solution containing magnesium nitrate and silver nitrate?
$1.Zn$ is oxidised
$2.M{g}^{2+}$ is reduced
$3.A{g}^{+}$ is reduced
$4.$ No reaction takes place

• A. $1$ and $2$ only
• B. $1$ and $3$ only
• C. $1,2$ and $3$ only
• D. $4$ only

Answer 1

Answer: (B)

$1$ and $3$ only

$\to$ The electrodes with relatiely positive value of electrode potential suggest that forward reaction [reduction reaction involving the addition of electrons] is not possible.However, electrodes with relatively negative value of electrode potential suggest that reverse reaction [oxidation reaction involving loss of electrons] is feasible.

$\to$Electrode potential of

$Zinc\to -0.763$

$M{g}^{2+}\to -2.37$

$A{g}^{+}\to +0.799$

$\to$ When Zinc is added to Magnesium Nitrate, it does not react with it. Magnesium is more reactive than Zinc and so, it has higher tendency to form positive ions than Zinc. Hence, Zinc cannot replace the magnesium ions in the compound.

$\to$ Zinc will get oxidized and replace silver in silver nitrate. $A{g}^{+}$ will get reduced.