On dissolving a non volatile and non electrolyte solute in water the vapour pressure of water decreases to 740 mm - Chemistry - Solutions

Question

On dissolving a non volatile and non electrolyte solute in water
the vapour pressure of water decreases to 740 mm hg The molality of
solution approximately will be

Vartika Jain · Accepted Answer

Dear Student,

At RT, Vapour pressure of water (P°)=760 mmHgVapour pressure on addition of solute (P)=740 mmHgWe know that,P°-PP° = x2where x2 is the mole fraction of soluteSo, x2 = 760-740760=20760=0
026Molality (m ) =1000x2x1M1where M1 is the molar mass of solventSolvent is water here so M1=18 gmol-1x1=1-0
026=0 974So, m =1000×0 0260 974×18=1
48 molal

On dissolving a non volatile and non electrolyte solute in water the vapour pressure of water decreases to 740 mm hg. The molality of solution approximately will be