A solid consists of a mixture of NaNO3 and Mg(NO3)2. When 6.75 g of the solid is dissolved in 50.0 g water, the freezing point is lowered by 5.35°C. What is the composition, by mass, of the solid?
van't hoff factor for NaNO3, i = 2 2 ions for every formula unit dissociated
van't hoff factor for Mg(NO3)2, i = 3 3 ions for every formula unit dissociated
Kf of water = 1.86 C/m
molar mass : NaNO3 = 85 g/mol
Mg(NO3)2 = 148 g/mol
mass of water = 50 g
mass of NaNO3 + Mg(NO3)2 = 6.75 ...
The expert examines composition by mass of NaNO3 mixed with Mg(NO3)2.