Question

The boiling point of water is elevated when 125 g of ethylene glycol (C₂H₆O₂) is dissolved in 1200 g of water. What is the new boiling point of water? Kb for water is 0.52 C°/m.

Answer 1

100.87°C

Step-by-step explanation:

This is about elevation of boiling point, one of the colligative properties.

Formula is:

Boiling T° of solution - Boiling T° of pure solvent = Kb . m . i

Kb is the boiling constant.

m means molality (mol/kg of solvent)

i = numbers of ions dissolved.

Our solute is C₂H₆O₂. As it is an organic compound, no ion is generated, so i = 1.

We determine moles of solute: 125 g . 1mol /62g = 2.02 moles.

We determine molality = 2.02 mol / 1.2 kg → 1.68 m.

Boiling T° of solution - 100°C = 0.52°C/m . 1.68m . 1

Boiling T° of solution = 0.52°C/m . 1.68m . 1 + 100°C → 100.87 °C