Dilarutkan 6 gram suatu zat non elektrolit dalam 90 gram air, ternyata tekanan uap jenuh larutan 23,53 mmHg. Bila tekanan uap jenuh air 24 mmHg, masa molekul re

P = P° × xp
23.53 = 24 × xp
xp = 0.98
xp (fraksi mol pelarut)
np (mol pelarut), nt (mol terlarut)

np= 90/18 = 5
xp = np / (np+nt)
0.98 = 5/(5+nt)
5+nt = 5/0.98 = 5.099 = 5.1
nt= 0.1

Mr = massa/ nt = 6/0.1 = 60 gram/mol