Question

Which of the following is the cell reaction that occurs when the following half-cells are combined?
$I_2+2e^{-}\to 2I^{-}\left(1M\right)$; $E^o=+0.54$V
$B{r}_2+2e^{-}\to 2B{r}^{-}\left(1M\right);E^o=+1.09$V

• A. $2B{r}^{-}+I_2\to B{r}_2+2I^{-}$
• B. $I_2+B{r}_2\to 2I^{-}+2B{r}^{-}$
• C. $2I^{-}+B{r}_2\to I_2+2B{r}^{-}$
• D. $2I^{-}+2B{r}^{-}\to I_{2}B{r}_2$

Answer 1

Answer: (C)

A galvanic cell or simple battery is made of two electrodes. Each of the electrodes of a galvanic cell is known as a half cell. In a battery, the two half cells form an oxidizing-reducing couple. When two half cells are connected via an electric conductor and salt bridge, an electrochemical reaction is started.

Reduction potential of both $I_2$ and $B{r}_2$ is given. We have to note that more the value of reduction potential then less the element has the tendency to get reduced and hence $I_2$ having more reduction potential acts as anode i.e. undergoes oxidation. And $B{r}_2$ having less reduction potential than $I_2$ undergoes reduction and acts as cathode.

$2I^{-}\to I_2+2e^{-}$ (Oxidation)
$B{r}_2+2e^{-}\to 2B{r}^{-}$ (Reduction)
$\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$
$2I^{-}+B{r}_2\to I-2+2B{r}^{-}$ is net cell reaction
$\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$

Hence option (C) is correct.