# An aqueous solution of 2 per cent (wt.//wt) non-volatile solute exerts a pressure of 1.004 bar at the boiling point of the solvent. What is the

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An aqueous solution of 2 per cent (wt.//wt) non-volatile solute exerts a pressure of 1.004 bar at the boiling point of the solvent. What is the molecular mass of the solute?
A. "23.4 g mol"^(-1)
B. "41.35 g mol"^(-1)
C. "10 g mol"^(-1)
D. "20.8 g mol"^(-1)

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Vapour pressure of pure water at boiling point =1 atm = 1.013 bar
Vapour pressure of solution (p_s)=1.004 bar
Let mass of solution = 100 g
Mass of solute=2 g
Mass of solvent = 100-2= 98 g
(p^@-p_s)/p^@=n_2/(n_1+n_2)=n_2/n_1 =(W_2//M_2)/(W_1//M_1) ( because n_2 lt lt lt n_1)
(1.013-1.004)/1.013=2/M_2xx18/98
or M_2=(2xx18)/98xx(1.013)/0.009 = 41.35 g mol^(-1)