Twenty grams of a substance were dissolved in 500ml. Of water and the osmotic pressure of the solution was found to be 600mm of mercury at `15^(@)"C".` Determine the molecular weight of the substance.

Options

A. 1120
B. 1198
C. 1200
D. None of these

Answer

B

Explanation

Here it is given that
w = 20 gm , V = 500 ml .
= `500/1000` = 0.5 litre
`pi=600mm=600/760atm,`
T = 15 + 273 = 288 K
m = ?
According to Van’t Hoff equation ,
`piV=nST`
`piV=w/MST`
`:.m=(wST)/(piV)=(20xx0.0821xx288xx760)/(600xx0.5)=1198`