Question

Assuming the van't hoff factor of FeCl3 is 3.4. Calculate the mass of the solute required to produce the aqueous solution of iron chloride that has 300g of water and a boiling point of 103 degrees celcius.

Answer 1

Boiling point elevation

T = i x Kb x m

(103 - 100) = 3°C = 3.4 x 0.512 °C/m x moles of solute /mass of water

moles of solute /mass of water = 1.723

moles of solute = 1.723 x 0.300 kg

= 0.517 moles

Mass of iron chloride = moles x molecular weight

= 0.517 moles x 162.206 g/mol

= 83.86 g