Answer to Question #165784 in General Chemistry for Phyroe

Question

Assuming that the following salt solution have effective ion concentration equal to the actual salt concentration determine the approximate freezing point of the solution: 

 A 0.1 F potassium sulfate solution.

Answer 1

$\Delta T_f=i×m×K_f...... (i)$

where $\Delta T_f$  is the freezing point depression,i is the vanhoff's factor, m is the molality of the solute and $K_f$  is the freezing point depression constant

here value of K_f for water is 1.86 , m is 0.1

now calculating value of $i$

As potassium sulfate solution will undergo 100 % dissociation

So the total 3 ions are formed on 100% dissociation so value of $i$ =3

Substituting these values in the equation (1) we get $\Delta T_f=3×0.1×1.86=0.558°C$

Freezing point =$T_f-\Delta T_f =(0-0.558) °C$

$=-0.558°C$