Name: Solutions Which Deviate From Ideal Behaviour
Uploaded: 2019-07-19
Duration: 6 min 38 s
Description: Non-ideal solutions are the solutions that do not follow Raoult's law at all in their compositions. Let's discuss how these solutions deviate from ideal beha...

Question

19.5 g

of

{CH}_{2} FCOOH

is dissolved in

500 g

of water. The depression in the freezing point of water observed is

1 . 0^{°} C

. Calculate the Van't Hoff factor and dissociation constant of fluoroacetic acid.

Accepted Answer

Given :

$∆ T_{f} = 1 {}^{o}C$

$K_{f} = 1.86$

Weight of solute, $w_{2} = 19.5 g$

Weight of solvent, $w_{1} = 500 g$

Observed molecular mass can be calculated by using the formula

$M_{2} = \frac{1000 \times K_{f} w_{2}}{w_{1} ∆ T_{f}} = \frac{1000 \times 1.86 \times 1.95}{500 \times 1} = 72.54 g {mol}^{- 1}$

Calculated molecular mass of ${CH}_{2} FCOOH$ is,

$M_{2} = 12 + 2 + 19 + 12 + 2 \times 16 + 1 = 78 g / mol$

Van't Hoff factor, $i = \frac{M_{2} (calculated)}{M_{2} (observed)} = \frac{78}{72.54} = 1.0753$

Degree of dissociation, $α$ = $\frac{i - 1}{n - 1}$

Here, $n =$ Number of ions produced after dissociation $= 2$

$i =$ Van't Hoff factor

$α = \frac{1.0753 - 1}{2 - 1} = 0.0753$

${CH}_{2} FCOOH \leftrightarrow {CH}_{2} {FCOO}^{-} + H^{+} C 0 0 At equilibriumC (1 - α) Cα Cα K_{a} = \frac{CαCα}{C (1 - α)} = \frac{{Cα}^{2}}{1 - α} K_{a} = \frac{0.5 \times {(0.0753)}^{2}}{(1 - 0.0753)} = 3.06 \times 10^{- 3}$

$19.5 g$ of ${CH}_{2} FCOOH$ is dissolved in $500 g$ of water. The depression in the freezing point of water observed is $1 . 0^{°} C$ . Calculate the Van't Hoff factor and dissociation constant of fluoroacetic acid.

Important Questions on Solutions

Learn and Prepare for any exam you want !

19.5 g of CH2FCOOH is dissolved in 500 g of water. The depression in the freezing point of water observed is 1.0°C. Calculate the Van't Hoff factor and dissociation constant of fluoroacetic acid.

Important Questions on Solutions

Learn and Prepare for any exam you want !

$19.5 g$ of ${CH}_{2} FCOOH$ is dissolved in $500 g$ of water. The depression in the freezing point of water observed is $1 . 0^{°} C$ . Calculate the Van't Hoff factor and dissociation constant of fluoroacetic acid.