Question

$0.5$ Faraday of electricity was passed to deposit all the copper present in $500$ ml of $CuS{O}_4$ solution. What was the molarity of this solution?

• A. $1$M
• B. $0.5$M
• C. $0.25$M
• D. $2.5$M

Answer 1

The correct option is B $0.5$M

Let molarity of solution b $xM$

number of mole in 500 ml, $n=500\times {10}^{-3}\times x$

$=0.5x$

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

$2F$ electricity needs for $1molCu$

$0.5$ electricity needs for $=\frac{1}{2}\times 0.5molCu=\frac{1}{4}molCu$

$=\frac{1}{4}=0.5x$

$x=\frac{1}{4\times 0.5}=0.5M$

Hence, the correct option is $B$