Question

What volume of $N{H}_3$ gas at $STP$ would be needed to prepare $100ml$ of $2.5$ molal $\left(2.5m\right)$ ammonium hydroxide solution?

• A. $0.056$ liters
• B. $0.56$ liters
• C. $5.6$ liters
• D. $11.2$ liters

Answer 1

The correct option is C $5.6$ liters

$2.5$ molal $N{H}_{4}OH$ means $2.5$ moles of $N{H}_3$ in $1000g{H}_{2}O$

Hence, $100cc$ solution of $N{H}_3$ requires $=0.25$ mole

$=0.25\times 22.4L=5.6L.$