Question

Calculate the boiling point of a solution of 500.0 g of ethylene glycol (C2H6O2) dissolved in 500.0 g of water. Kf = 1.86°C/m and Kb = 0.512°C/m. Use 100°C as the boiling point of water.

Answer 1

To calculate the boiling point of the solution, use the equation ΔT = Kb * molality, where ΔT is the boiling point elevation, Kb is the boiling point elevation constant, and molality is the molal concentration of the solution. Calculate the molality by dividing the number of moles of ethylene glycol by the mass of water. Substitute the molality into the equation to calculate the boiling point elevation, and add this elevation to the boiling point of pure water (100°C) to find the boiling point of the solution.

Step-by-step explanation:

To calculate the boiling point of the solution, we need to use the equation:

ΔT = Kb * molality

Where ΔT is the boiling point elevation, Kb is the boiling point elevation constant, and molality is the molal concentration of the solution.

First, we need to calculate the molality of the solution by dividing the number of moles of ethylene glycol by the mass of water. The number of moles of ethylene glycol can be found by dividing the mass of ethylene glycol by its molar mass, and the mass of water is given as 500.0 g.

Once we have the molality, we can substitute it into the equation to calculate the boiling point elevation. Finally, we add this elevation to the boiling point of pure water (100°C) to find the boiling point of the solution.

Answer 2

The boiling point of a solution of 500.0 g of ethylene glycol dissolved in 500.0 g of water is 108.258°C.

Step-by-step explanation:

Elevation in boiling point :
`\Delta T_b`

`\Delta T_b=T_b-T`

`\Delta T_b=K_b* m`

`T_b` = Boiling point of the solution

T = Boiling point of pure solvent

`K_b`= Molal elevation constant of solvent

m = molality of the solution

Molality of the ethylene glycol solution:

`molality=\frac{\text{Moles of solute}}{\text{Mass of solvent in kg}}`

Moles of ethylene glycol =
`(500.0 g)/(62 g/mol)=8.0645 mol`

Mass of solvent that uis water = 500.0 g = 0.5000 kg

`m=(8.0645 mol)/(0.5000 kg)=16.1290 m`

Molal elevation constant of water =
`K_b=0.512^oC/m`

`\Delta T_b=0.512^oC/m* 16.1290 m=8.258^oC`

Boiling point of the solution =
`T_b`

Boiling point of pure water = T = 100°C

`T_b=T+\Delta T_b=100^oC+8.258^oC=108.258^oC`

The boiling point of a solution of 500.0 g of ethylene glycol dissolved in 500.0 g of water is 108.258°C.