Question

pH of 1M HA (weak acid) is 3. Hence, van't Ho
factor is​

Answer 1

Answer: The Van't Hoff factor is 1.001

Explanation:

To calculate the hydrogen ion concentration in the solution, we use the equation:

$pH=-\log[H^+]$

We are given:

pH of the solution = 9

Putting values in above equation, we get:

$3=-\log[H^+]$

$[H^+]=10^{-3}M$

Van't hoff factor is defined as the ratio of observed colligative property to the calculated colligative property.

Mathematically,

$i=\frac{\text{observed colligative property}}{\text{Calculated Colligative property}}$         ........(1)

The chemical equation for the dissociation of HA follows:

                      $HA\rightleftharpoons H^++A^-$

Initial:            1

At eqllm:     $1-\alpha$     $\alpha$    $\alpha$

Total concentration after dissociation =  $(1-\alpha+\alpha+\alpha)=1+\alpha$

Observed colligative property = $(1+\alpha)=(1+10^{-3})=(1+0.001)=1.001$

Calculated colligative property = 1

Putting values in equation 1, we get:

$i=\frac{1.001}{1}=1.001$

Hence, the Van't Hoff factor is 1.001