Question

Zinc displaces hydrogen from acid solution (\[\ce{E^{\circ}_{Zn^{2+}/Zn}}\] = −0.76 V). Explain.

Answer 1

Zinc displaces hydrogen from acid solution because it has a lower (more negative) standard reduction potential than hydrogen.

\[\ce{E^{\circ}_{Zn^{2+}/Zn}}\] = −0.76 V

\[\ce{E^{\circ}_{H^+/H_2}}\] ​= 0.00 V

Since zinc’s reduction potential is more negative, it is more easily oxidised than hydrogen. Thus, zinc donates electrons to H⁺ ions (from the acid), reducing them to hydrogen gas.

\[\ce{Zn_{(s)} + 2H^+_{ (aq)} −> Zn^{2+}_{ (aq)} + H2_{(g)}}\]