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 of 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.