How does molar mass affect the freezing point?

1 Answer
Jun 14, 2018

see below


a common relation for freezing point of a solution is:
#Delta T_f = i xx m xx K_f#
where the decrease of the frezing temperature is proportional to the number of ions the you have from the ionization of the solute (i), to a costant that depends also from the MM of the solvent (more is big the MM more is the valour of the costant) and to m that is the molality, that is the number of mol of solute in 1000 g of solvent.

If you have a certain amount in gramms of solute, the number of mol is smaller, how much its MM is highter, infact:
N° mol = (mass)/(molar mass)
so, for example, 100 g of LIF (MM =26 g/mol)are almost 4 mol while 100g of KI (MM= 168) is little more than 1/2 mol