Question

In the laboratory two solutions, one of glucose (molar mass $=180g/mol$), the other of sucrose(molar mass$=342g/mol$) are made. If glucose solution had $180$ grams in $1,000$ grams of water and the sucrose had $342$ grams in $1,000$ grams of water, which statement about the freezing points of the solutions is the most accurate?

• A. The glucose solution would have the lower freezing point
• B. The sucrose solution would have the lower freezing point
• C. The freezing point of the sucrose solution would be lowered twice as much as that of the glucose solution
• D. Both solutions would have the same freezing point
• E. The freezing points of the solutions would not be affected, because both solutes are nonpolar

Answer 1

Answer: (D)

Both solutions would have the same freezing point

The depression in freezing point is given by

$\Delta T_f=K_{f}m$

For same $K_f$,

$\Delta T_f\propto m$

Since the molality of both the solutions are same, the depression in freezing point would also be same. Hence, both the solutions will have the same freezing point