Calculate the vapor pressure lowering of a solution of 280 g

Calculate the vapor pressure lowering of a solution of 2.80 g of aspirin (molecular weight = 180.15 g/mol) in 45.0 g of methanol (CH₃OH) at 21.2

Solution

moles of aspirin=2.8/180.15

=0.0155 moles

so,

moles of methanol=45/32

=1.40625

so

p/Po=n/No

or p/101 = 0.0155/(0.0155+1.40625)

or p=1.1011 torr