Answer:
The freezing point of solution = -0.34 °C
The boiling point of solution = 82.98 °C
Explanation:
Step 1: Data given
Mass of naphthalene = 14.2 grams
Molar mass naphthalne = 128.17 g/mol
Volume of benzene = 111.0 mL
Density of benzene = 0.877 g/mL
Kf(benzene)=5.12°C/m
Freezing point benzene = 5.5 °C
Kb(benzene)=2.53°C/m
Boiling point benzene = 80.1 °C
Step 2: Calculate mass of benzene
Mass benzene = density * volume
Mass benzene = 0.877 g/mL * 111.0 mL
Mass benzene = 97.3 grams
Step 3: Calculate moles naphthalene
Moles naphthalene = mass naphthalene / molar mass napthalene
Moles napthalene = 14.2 grams / 128.17 g/mol
Moles naphthalene = 0.111 moles
Step 4: Calculate molality
Molality = moles naphthalene / mass benzene
Molality = 0.111 moles / 0.0973 kg
Molality = 1.14 molal
Step 5: Calculate freezing point of a solution
ΔT = i*kf*m
ΔT = 1 * 5.12 °C/m * 1.14 m
ΔT = 5.84 °C
ΔT = T(pure solvent) − T(solution)
The freezing point of solution = T pure - ΔT
5.5 - 5.84 = -0.34 °C
The freezing point is -0.34 °C
Step 6: Calculate boiling point of a solution
ΔT = i*kb*m
ΔT = 1 * 2.53 °C/m * 1.14 m
ΔT = 2.88 °C
ΔT = Tb (solution) - Tb (pure solvent)
The boiling point of solution = T pure + ΔT
The boiling point of solution = 80.1 °C + 2.88
The boiling point of solution = 82.98 °C
