1,1,2: Boiling point elevation

Equation for change in boiling point

∆Tb = i∙Kb∙m ∆Tb = Difference in boiling point i = Van Hoff's factor = Number of dissociated moles of particles per mole of solute = 1 for all non-electrolyte solues, equals number of ions released for electrolytes Kb = Boiling point elevation constant, depending on used solvent m = Concentration in molality

Definition

Boiling point is the temperature where vapour pressure equals atmospheric pressure. If this is increased, we need a higher temperature, more energy, to reach this point.

Consequences from adding a non-volatile solute

Decreased freezing point Decreased vapour pressure Increased boiling point Increased osmotic pressure