`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 = `10 g`
Number of moles of glucose = `0.0556`
Mass of sucrose = `20 g`
Number of moles of sucrose =`0.0585`
Mass of water =`100 g`
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^(@)`
`= 5.556 / 5.67 xx 30 = 29.3 mm Hg`