Calculate the freezing point and boiling point of a solution containing 14.8g of naphthalene (C10H8) in 120.0mL of benzene. Benzene has a density of 0.877 g/cm3.

F.P: -7 degrees celsius

B.P: 102 degrees celsius

To calculate the freezing point and boiling point of a solution, we need to use the concept of colligative properties. The freezing point depression and boiling point elevation depend on the molality (mol solute/kg solvent) of the solution.

First, we need to determine the molality of the naphthalene solution. We can find the number of moles of naphthalene by dividing its mass by its molar mass.

Molar mass of naphthalene (C10H8) = 10(12.01 g/mol) + 8(1.01 g/mol) = 128.18 g/mol

Number of moles of naphthalene = 14.8 g / 128.18 g/mol = 0.1154 mol

Next, we need to calculate the mass of benzene in the solution. We can use the density and volume of benzene provided.

Mass of benzene = density × volume
= 0.877 g/cm^3 × 120.0 mL
= 0.877 g/mL × 120.0 mL
= 105.24 g

To calculate the molality, we divide the number of moles of naphthalene by the mass of benzene (converted to kg).

Molality (m) = moles of solute / mass of solvent (in kg)
= 0.1154 mol / 105.24 g × (1 kg / 1000 g)
= 0.001096 mol/kg

Now we can use the molality to calculate the freezing point depression and boiling point elevation constants.

For the freezing point depression:
ΔTf = Kf × m

The freezing point depression constant (Kf) for benzene is approximately 5.12 °C/m.

ΔTf = 5.12 °C/m × 0.001096 mol/kg
= 0.00562 °C

The freezing point of benzene is 5.5 °C, so the freezing point of the naphthalene solution is:
Freezing point = 5.5 °C - 0.00562 °C
= 5.494 °C

For the boiling point elevation:
ΔTb = Kb × m

The boiling point elevation constant (Kb) for benzene is approximately 2.53 °C/m.

ΔTb = 2.53 °C/m × 0.001096 mol/kg
= 0.00277 °C

The boiling point of benzene is 80.1 °C, so the boiling point of the naphthalene solution is:
Boiling point = 80.1 °C + 0.00277 °C
= 80.10277 °C

Therefore, the freezing point of the solution containing naphthalene in benzene is approximately 5.494 °C, and the boiling point is approximately 80.10277 °C.

mass benzene = volume x density = ?

mols benzene = grams/molar mass = ?
m benzene = mols benzene/kg solvent

For f.p.: delta T = Kf*m, then subtract delta T from 0C to find new f.p.

For b.p.: delat T = Kb*m, the add delta T to 100 C to find new b.p.