Question

Write balanced equation for the following reaction:

(d) Zinc is treated with cold dilute sodium hydroxide solution.

Answer 1

Reaction summary:

• When Zinc $\left(\mathrm{Zn}\right)$ reacts with cold dilute Sodium hydroxide $\left(\mathrm{NaOH}\right)$, Sodium zincate $\left({\mathrm{Na}}_2{\mathrm{ZnO}}_2\right)$ is formed along with the release of Hydrogen gas $\left({\mathrm{H}}_2\right)$.

Skeleton reaction:

$\mathrm{Zn}\left(\mathrm{s}\right)+\mathrm{NaOH}\left(\mathrm{aq}\right)\to {\mathrm{Na}}_2{\mathrm{ZnO}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\uparrow$

• In the above unbalanced reaction, there is $1$ atom of sodium on reactant side while there are $2$ atoms of sodium on product side.
• Thus, in order to balance this, one we will write a stoichiometric coefficient $2$ in front of $\mathrm{NaOH}$ on reactant side and this will balance all the other atoms too.

Balanced chemical reaction:

$\mathrm{Zn}\left(\mathrm{s}\right)+2\mathrm{NaOH}\left(\mathrm{aq}\right)\to {\mathrm{Na}}_2{\mathrm{ZnO}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\uparrow$