Question

A certain current liberated $0.504g$ of hydrogen in $2$ hours. How many grams of copper can be liberated by the same current flowing for the same time in $CuS{O}_4$ solution?

• A. $12.7g$
• B. $15.9g$
• C. $31.8g$
• D. $63.5g$

Answer 1

The correct option is B $15.9g$

$H^{+}+e^{-}\to 0.5H_2$

moles of $H_2=\frac{0.504}{2}=0.252moles$

moles of electrons consumed$=0.504moles$

charge passed$=0.504\times 96500=48636C$

$current\left(I\right)=\frac{48636}{2\times 3600}=6.755A$

${Cu}^{2+}+2e^{-}\to Cu$

Same current passed for same time, hence charge passed is same.

Also, moles of $e^{-}$ are same.

moles of $Cu$ for $0.504$ moles $e^{-}=\frac{0.504}{2}=0.252moles$

weight of $Cu$$=0.252\times 63.5=15.9g$