Question

When benzene freezes at 5.5oc its density changes from 0.879 g/cm3 to 0.891 g/cm3. its enthalpy of fusion is 10.59 kj/mol. estimate the freezing point of benzene at 1000 atm.

Answer 1

To estimate the freezing point of benzene at 1000 atm, we can use the formula: ΔTf = (Kf * m) / (i * M). Given the change in freezing point, the freezing point depression constant for benzene, and assuming ideal solution behavior, we can solve for the molar mass of the solute.

Step-by-step explanation:

To estimate the freezing point of benzene at 1000 atm, we can use the formula:

ΔTf = (Kf * m) / (i * M)

Where:

ΔTf is the change in freezing point

Kf is the freezing point depression constant for benzene

m is the molality of the solution

i is the van't Hoff factor (which is 1 for benzene)

M is the molar mass of the solute

Given that the change in freezing point is 5.5 °C - 0.4 °C = 5.1 °C, the freezing point depression constant for benzene is 5.12 K kg/mol, and assuming ideal solution behavior, we can solve for M:

5.1 °C = (5.12 K kg/mol * m) / (1 * M)

Solving for M, we find that the molar mass of the solute is approximately 105 g/mol.