Question

Write three complete and balanced pairs of below mention electrochemical half reactions. For each pair of reactions, identify which reaction is the cathode reaction and which reaction is the anode reaction,
a. Cu → Cu2+ +2e-
b. 2H+ 2e →H2
c. O2- → 1/2O2 + 2e

Answer 1

Answer: a) $Cu\rightarrow Cu^{2+}+2e^-$  : anode

b. $2H^++2e^-\rightarrow H_2$ : cathode

c. $O^{2-}\rightarrow \frac{1}{2}O_2+2e^-$:  anode

Explanation:

Electrochemical cell is a device which converts chemical energy into electrical energy. It consist of two electrodes, anode and cathode.

Oxidation i.e. loss of electrons , which results in an increase in oxidation number occurs over anode.

Reduction i.e. gain of electrons, which results in decrease in oxidation number occurs over cathode.

a. $Cu\rightarrow Cu^{2+}+2e^-$  : oxidation :  anode

b. $2H^++2e^-\rightarrow H_2$ : reduction : cathode

c. $O^{2-}\rightarrow \frac{1}{2}O_2+2e^-$: oxidation : anode