What is the expected boiling point of a solution made by combining 400.0 g of water with 100.0 g of Na₂CO₃?

Question

Quizplus · Accepted Answer

The boiling point of a solution is elevated by the addition of a non-volatile solute. The boiling point elevation is directly proportional to the molality of the solution. The molality of a solution is defined as the number of moles of solute per kilogram of solvent. In this case, the solvent is water and the solute is Na₂CO₃. The molar mass of Na₂CO₃ is 105.99 g/mol. Therefore, the number of moles of Na₂CO₃ in 100.0 g is 100.0 g / 105.99 g/mol = 0.944 mol. The mass of water in the solution is 400.0 g. Therefore, the molality of the solution is 0.944 mol / 0.400 kg = 2.36 mol/kg. The boiling point elevation constant for water is 0.512 °C/mol/kg. Therefore, the boiling point elevation is 2.36 mol/kg x 0.512 °C/mol/kg = 1.21 °C. The boiling point of pure water is 100.0 °C. Therefore, the expected boiling point of the solution is 100.0 °C + 1.21 °C = 101.2 °C.

What Is the Expected Boiling Point of a Solution Made