Question

Same amount of electric current is passed through solutions of $AgN{O}_3$ and $H_{2}O$. If 1.08 g of silver is obtained in the first case, the amount of hydrogen liberated at S.T.P. in the second case is:

• A. $224c{m}^3$
• B. $1.008g$
• C. $112c{m}^3$
• D. $22400c{m}^3$

Answer 1

Answer: (C)

$112c{m}^3$

The molar mass of $Ag$ is 108 g/mol.
Let $n$ be the number of moles of hydrogen liberated

$A{g}^{+}+e^{-}\to Ag$

$2H^{+}+2e^{-}\to H_2$

Thus 1 mole of hydrogen corresponds to 2 moles of silver.
Number of moles of hydrogen liberated

$\frac{1.08}{108}=2\times n$

$n=0.005$

At S.T.P, 1 mole of hydrogen occupies a volume of $22400c{m}^3$

0.005 moles of hydrogen will occupy a volume of $0.005\times 22400=112c{m}^3$