Calculate the vapour pressure of 10% (w/w) aqueous glucose solution at `30^@C`, if vapour pressure of pure water is 31.8 mm.

Explanation

100 grams solution = 10 grams glucose + 90 g water.
Number of moles of glucose, `n_1 = 10//180 = 1//18`.
Number of moles of water, `n_2 = 90//18 = 5`
`(p^@ - p)/(p^@) = (n_1)/(n_1 + n_2) , (31.8 - p)/(31.8) = (1//18)/(5 + 1//18)`
Vapour pressure of solution, `p - 31.8 (1 - 1//91) = 31.45 mm`.