Question

The vapour pressure of 100 g of water reduces from 17.53 mm to 17.22 mm when 17.10 g, of substance X is dissolved in it. Substance X can be ______.

पर्याय

• methanol

• glucose 

• carbon dioxide 

• cannot predict

Answer 1

The vapour pressure of 100 g of water reduces from 17.53 mm to 17.22 mm when 17.10 g, of substance X is dissolved in it. Substance X can be glucose.

Explanation:

Given p° = 17.53, p_s = 17.22 and W = 17.10

`("p"^circ - "p"_"s")/"p"^circ = "n"/("n + N") = ("w"/"m")/("w"/"m" + "W"/"M")`

`because "w"/"m" "<<" "W"/"M"`

`therefore ("p"^circ - "p"_"s")/"p"^circ = ("w"//"m")/("W"//"M")` 

`= "w"/"m" xx "W"/"M"`

`therefore (17.53 - 17.22)/17.53 = 17.10/"m" xx 18/100`

`=> "m" = (17.10 xx 18 xx 17.53)/(0.31 xx 100)`

⇒ m = 174.05