Write the equations for the reaction of zinc with each of the following:
(a) sodium hydroxide solution.
(b) dilute sulphuric acid.
(c) copper sulphate solution.

(a) Zinc reacts with an aqueous solution of sodium hydroxide and forms sodium hydroxy zincate, with the evolution of hydrogen gas.

$$\begin{gathered} \mathrm{Zn}+2\mathrm{NaOH}+2{\mathrm{H}}_2\mathrm{O}\stackrel{}{\to }{\mathrm{Na}}_2\mathrm{Zn}(\mathrm{OH}{)}_4+{\mathrm{H}}_2 \\ \mathrm{Zinc}\mathrm{Sodium}\mathrm{hydroxide}\mathrm{Solu}.\mathrm{Sodium}\mathrm{hydroxy}\mathrm{zincate}\mathrm{Hydrogen}\mathrm{gas} \end{gathered}$$

(b) Because zinc is more reactive than hydrogen, it reacts with dilute sulphuric acid and the displaced hydrogen from the acid, forming zinc sulphate and liberating hydrogen gas.

$$\begin{gathered} \mathrm{Zn}+{\mathrm{H}}_2{\mathrm{SO}}_4\stackrel{}{\to }{\mathrm{ZnSO}}_4+{\mathrm{H}}_2 \\ \mathrm{Zinc}\mathrm{Sulphuric}\mathrm{acid}\mathrm{Zinc}\mathrm{sulphate}\mathrm{Hydrogen}\mathrm{gas} \end{gathered}$$

(c) Because zinc is more reactive than copper, it displaces copper from its salt solution. On adding zinc, the blue colour of copper sulphate solution becomes colourless and a reddish brown copper metal is formed.

$$\begin{gathered} \mathrm{Zn}\left(\mathrm{s}\right)+{\mathrm{CuSO}}_4\left(\mathrm{aq}\right)\stackrel{}{\to }{\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)+\mathrm{Cu}\left(\mathrm{s}\right) \\ \mathrm{Zinc}\mathrm{Copper}\mathrm{sulphate}\mathrm{Zinc}\mathrm{sulphate}\mathrm{Copper} \end{gathered}$$