the elevation of boiling point (ΔTb) is directly proportional to the molal concentration of
the solute in a solution. Thus
ΔTb ∝ m
or ΔTb = Kbm
Here m (molality) is the number of moles of solute dissolved in 1 kg
of solvent and the constant of proportionality, Kb is called Boiling Point
Elevation Constant or Molal Elevation Constant (Ebullioscopic
Constant). The unit of Kb is K kg mol-1.
Molarity (M) is defined as number of moles of solute dissolved in one litre (or one cubic decimetre) of solution.
(a) Mol. mass of
Volume of solution = 4.3 L
(b) Number of moles present in 1000 ml of 0.5M H2SO4= 0.5 mol
therefore number of moles present in 30ml of 0.5M H2SO4=mol =0.015mol
therefore molarity =0.015/0.5L
thus molarity is 0.03M
Molality (m) is defined as the number of moles of the solute per kilogram (kg) of the solvent and is expressed as:
Calculate (a) molality (b) molarity and (c) mole fraction of KI if the density of 20% (mass/mass) aqueous KI is 1.202 g mL-1.