1.

The vapour pressure of acetone at 20^(@)C is 185 torr. When 1.2 g of a non-volatile substance was dissolved in 100 g of acetone at 20^(@)C, its vapour pressure was 183 torr. The molar mass (g mol-') of the substance is :

Answer»

128
488
32
64

Solution :Using RELATION,
`(p^(@) -p_(s))/(p _(s))=(w_(2) M_(1))/(w_(1)M_(2))`
`w_(2), M_(2)=` mas in g and MOL MASS of solvcnt `w_(2), M _(2)=` mass in g and mol. Mass of solutc
Let `M_(2) =x`
`p^(@)=185` torr
`p _(s) =183 ` torr
`(185-183)/(183)=(1.2xx58)/(100x)` (mol. mass of acctone = 58)`
`x= 64`
`THEREFORE ` Molar mass of SUBSTANCE = 64


Discussion

No Comment Found

Related InterviewSolutions