Question

$108 \, g$ of silver (molar mass $108 \, g$ $mol^{- 1}$ ) is deposited at cathode from $AgNO_{3}$ (aq) solution by a certain quantity of electricity. The volume (in L) of oxygen gas produced at $273 \, K$ and $1$ bar pressure from water by the same quantity of electricity is

• A. $2.82 \, L$
• B. $5.675 \, L$
• C. $1.41 \, L$
• D. $0.746 \, L$

Answer 1

Answer: (B)

$\left[\right.n_{A g}\left]\right._{d e p o s i t}=\frac{108}{108}=1$ $mole$

$Ag^{+}+1e^{-} \rightarrow Ag$

1F charge is required for 1 mole of Ag

$H_{2}O \rightarrow \frac{1}{2}O_{2}+2H^{+}+2e^{-}$

2F charge deposit $=\frac{1}{2}$ mole

1F charge deposit $=\frac{1}{4}$ mole

$PV=nRT$

$V=\frac{1}{4}\times \frac{0. 0821 \times 273}{1}$

$V=5.675 \, L$