Question

Standard electrode potential for $Sn ^{4+} / Sn ^{2+}$ couple is $+0.15 V$ and that for the $Cr ^{3+} / Cr$ couple is $-0.74$. These two couples in their standard state are connected to make a cell. The cell potential will be

• A. +1.83 V
• B. +1.19 V
• C. + 0.89 V
• D. + 0.18 V

Answer 1

Answer: (C)

$E _{ Sn ^{4+} / Sn ^{2+}}^{0}=+0.15 V$
$E _{ Cr ^{3+} / Cr }^{0}=-0.74 V$
Now,
$E _{\text{cell} }^{0}= E _{ C }^{0}- E _{ A }^{0}$
$=0.15-(-0.74)$
$E _{\text{ cell }}^{0}=+0.89\, V$