Question

Which equation represents the reduction half-reaction for this redox equation?
Ca + Al(NO3)3 Al + Ca(NO3)2

Answer 1

Al³⁺ + 3e⁻ →  Al      the reduction half-reaction

Answer 2

Answer: The half reaction for reduction reaction is $Al^{3+}(aq.)+3e^-\rightarrow Al(s)$

Explanation:

Reduction reaction is defined as the reaction in which a substance gains electrons and the oxidation state of the substance is reduced.

Oxidation reaction is defined as the reaction in which a substance looses electrons and the oxidation state of the substance is increased.

For the given redox reaction:

$Ca(s)+Al(NO_3)_3(aq.)\rightarrow Al(s)+Ca(NO_3)_2(aq.)$

The half cell reactions for the above redox equation is:

Oxidation: $Ca(s)\rightarrow Ca^{2+}(aq.)+2e^-$

Reduction: $Al^{3+}(aq.)+3e^-\rightarrow Al(s)$

Hence, the half reaction for reduction reaction is $Al^{3+}(aq.)+3e^-\rightarrow Al(s)$