Question

1.5 g of a non-electrolyte solute dissolved in 75 g of benzene lowered the freezing point of benzene by 0.50 K Molal depres
sion constant of benzene is 5.12 K kg mol-1 Molar mass of the solute (in g mol-) is 224.8 204.8 102.4 208.4​

Answer 1

Answer:

As ΔT

f

=K

f

×m

where,

K

f

= Freezing point depression constant;

ΔT

f

= Depression in freezing point;

m= molality

Now,

ΔT

f

=K

f

×

M

2

×W

1

W

2

×1000

where,

W

2

= mass of solute; W

1

= mass of benzene i.e. solvent; M

2

= molar mass of solute

⇒0.40=5.12×

M

2

×50

1.0×1000

⇒M

2

=256

Thus, the molar mass of non-electrolyte is