Question

20 g of solute X are dissolved in 50 g of water. 15 g of solute Y are dissolved in 70 g of benzene. The

molalities of the solutes in these two solutions are the same. Hence, the ratio of the molecular

weights of solute X to that of the solute Y is​

Answer 1

Answer:

Explanation:

GIVEN :

wt. of solute X = 20 g

wt. of water = 50 g

wt. of solute Y = 15 g

wt. of benzene = 70 g

MOLALITY OF X = MOLALITY OF Y

TO FIND : Ratio of molecular weight of solute X to solute Y

SOLUTION :

molality of solution x = no. of moles of  solute x / wt. of solvent (g) x 1000

                           = given weight(X) × 1000/ molecular weight(X)× wt. of solvent (H₂O)

    Molality of x   = 20 x 1000 / X x 50

                                 = 400/X

similarly,

Molality of Y = given weight (Y) x 1000 / molecular weight (Y) x wt. of solvent ( benzene )

 Molality of solution (Y)  = 15 x 1000 / Y x 70  g

                                       = 214.28 / Y

Molality of X = Molality of Y

  $\frac{400}{X}$ = $\frac{214.28}{y}$

$\frac{X}{Y}$ = $\frac{400}{214.28}$

X : Y = 1.86 : 1

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