Question

Two samples of $C{H}_{3}COOH$ each of 10 g were taken separately in two vessels containing water of 6 litre and 12 litre respectively at ${27}^{0}C$.The degree of dissociation of $C{H}_{3}COOH$ will be:

• A. More in 12 litre vessel
• B. More in 6 litre vessel
• C. Equal in both vessels
• D. Half in 6 litre vessel than in 12 litre vessel

Answer 1

Answer: (B)

More in 6 litre vessel

Molar Concentration of sample$=\frac{10/60}{6}$

$=0.028$ $mol/L$

$C{H}_{3}COOH\leftrightharpoons C{H}_{3}CO{O}^{-}+H^{+}$

$0.02B$ $0$ $0$

$0.02B-0.02B{\alpha }_1$ $0.02B{\alpha }_1$ $0.02B{\alpha }_1$

$K_{\alpha }=\frac{\left(0.02B{\alpha }_1\right)\left(0.02B{\alpha }_1\right)}{0.02B\left(1.4\right)}$

$1.8\times {10}^{-15}=0.028{\alpha }_1^2$ ($1-{\alpha }_1\cong 1$)

${\alpha }_1=0.025$

Molar concentration of second sample$=0.0138$ $mol/L$

${\alpha }_2=\sqrt{\frac{K_a}{0.0138}}=\sqrt{\frac{1.3\times {10}^{-5}}{0.0138}}=0.036$

The correct answer is 0.036.