`10 g` of glucose (molar mass 180) and `20 g` of sucrose (molar mass 342) are dissolved in `100 g` of water. What will be the vapour pressure of the resultant solution if the vapour pressure of water is `30 mm Hg`?

Explanation

Mass of glucose = 10g
No. of moles of glucose = 0.0556
Mass of sucrose = 20g
No. of moles of sucrose = 0.0585
Mass of water = 100g
No. of moles of water = 5.556
Total number of moles `= 5.556+0.0585+0.0556`
`=5.67`
Mole fraction of water `= (5.556)/(5.67)`
Vapour pressure of solution = Mole fraction of water `xx p_(0)`
`=(5.556)/(5.67) xx 35 = 34.3` mm Hg.