Question

A constant current of $30\, A$ is passed through an aqueous solution of $NaCl$ for a time of $1.00\, h$. What is the volume of $Cl_2$ gas at STP produced?

• A. 30.00 L
• B. 25.08 L
• C. 12.54 L
• D. 1.12 L

Answer 1

Answer: (C)

Due to electrolysis
$2H_{2}O\left(l\right)+2e^{-} \rightarrow H_{2}\left(g\right)+2OH^{-}\left(aq\right)$
$\frac{2Cl^{-}\left(aq\right) \rightarrow Cl_{2}\left(g\right)+2e^{-} }{2H_{2}O\left(l\right)+2Cl^{-}\left(aq\right) \rightarrow H_{2}\left(g\right)+Cl_{2}\left(g\right)+2OH^{-}_{\left(aq\right)}}$
$\frac{ }{OH^{-} formed =NaOH formed =Z it }$
$=\frac{E}{96500}\times i\times1$
$=\frac{40}{96500}\times30\times1\times60\times60=44.77\, g$
$=\frac{44.77}{40}=1.12 \,mol$
$Cl_2$ formed = $\frac{1}{2}$ mol of $NaOH$
$=\frac{1.12}{2}=.056$ mol
$= 0.56 × 22.4 \,L$ at $STP = 12.54\, L$