Question

Choose the solvent below that would show the greatest freezing point lowering when used to make a 0.20 m nonelectrolyte solution. diethyl ether, kf = 1.79°c/m benzene, kf = 5.12°c/m chloroform, kf = 4.70°c/m ethanol, kf = 1.99°c/m carbon tetrachloride, kf = 29.9°c/m

Answer 1

Answer : Carbon tetrachloride,
`k_f=29.9^oC/m` will show the greatest freezing point lowering.

Explanation :

For non-electrolyte solution, the formula used for lowering in freezing point is,

`\Delta T_f=k_f* m`

where,

`\Delta T_f` = lowering in freezing point

`k_f` = molal depression constant

m = molality

As per question, the molality is same for all the non-electrolyte solution. So, the lowering in freezing point is depend on the
`k_f` only.

That means the higher the value of
`k_f`, the higher will be the freezing point lowering.

From the given non-electrolyte solutions, the value of
`k_f` of carbon tetrachloride is higher than the other solutions.

Therefore, Carbon tetrachloride,
`k_f=29.9^oC/m` will show the greatest freezing point lowering.