Question

In the electrolysis of water, which of the following is the cathode reduction reaction?

• A. $2H_{2}O\left(l\right)+2e^{-}\to H_2\left(g\right)+2O{H}^{-}+O_2\left(g\right)$
• B. $2H_{2}O\left(l\right)\to \frac{1}{2}{O}_2\left(g\right)+2H^{+}+2e^{-}$
• C. $2O{H}^{-}+2e^{-}\to O_2\left(g\right)+H_2\left(g\right)$
• D. $2H^{+}+2e^{-}\to H_2\left(g\right)$
• E. $2H_{2}O\left(l\right)+4e^{-}\to O_2\left(g\right)+2H_2\left(g\right)$

Answer 1

The correct option is D $2H^{+}+2e^{-}\to H_2\left(g\right)$

In the electrolysis of water, the cathode reduction reaction is $2H^{+}+2e^{-}\to H_2\left(g\right)$.
At cathode, hydrogen ions accept electrons to form hydrogen molecule. This is reduction reaction.
At anode, oxidation reaction generates oxygen molecules.