Question

Which among $\mathrm{Cu}$, $\mathrm{Fe}$, $\mathrm{Mg}$, $\mathrm{Na}$ and $\mathrm{Zn}$ does not react with a dilute $\mathrm{HCl}$ solution ?

Answer 1

• Copper does not react with a dilute $\left(\mathrm{HCl}\right)$ hydrochloride acid because, in the reactivity series, copper $\left(\mathrm{Cu}\right)$ is present below hydrogen which shows the less reactivity of copper than hydrogen.
• When $\left(\mathrm{Fe}\right)$ Iron reacts with dilute $\mathrm{HCl}$ solution then $\left({\mathrm{FeCl}}_2\right)$ Iron $\left(\mathrm{II}\right)$ chloride and hydrogen $\left({\mathrm{H}}_2\right)$ gas is produced.

$\mathrm{Fe}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{FeCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

Here, iron displaces hydrogen from hydrochloric acid to form iron chloride and hydrogen gas.

• When magnesium $\left(\mathrm{Mg}\right)$ reacts with the $\mathrm{HCl}$ solution then it forms a salt of magnesium chloride $\left({\mathrm{MgCl}}_2\right)$ and hydrogen gas.

$\mathrm{Mg}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}.\right)\to {\mathrm{MgCl}}_2\left(\mathrm{aq}.\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

• When sodium $\left(\mathrm{Na}\right)$ reacts with $\mathrm{HCl}$ solution then it forms sodium chloride $\left(\mathrm{NaCl}\right)$ and hydrogen ${\mathrm{H}}_2$ gas.

$2\mathrm{Na}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to 2\mathrm{NaCl}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

• When zinc $\left(\mathrm{Zn}\right)$ reacts with $\mathrm{HCl}$ solution then it gives zinc chloride $\left({\mathrm{ZnCl}}_2\right)$ with evolution of hydrogen ${\mathrm{H}}_2$ gas.

$\mathrm{Zn}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{ZnCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

Hence, from given elements, Copper $\mathbf{\left(}\mathbf{Cu}\mathbf{\right)}$ does not react with a dilute $\mathbf{HCl}$ solution.