Question

Determine the freezing point of a 0.765 m solution of nitrobenzene in naphthalene. (given: naphthalene Kf = 7.45o C Kg/ mole and the pure freezing point is 80.3o C) Report answers to one decimal place.

Answer 1

Answer: The freezing point of a 0.765 m solution of nitrobenzene in naphthalene is $74.6^0C$

Explanation:

Depression in freezing point is given by:

$\Delta T_f=i\times K_f\times m$

$\Delta T_f=T_f^0-T_f=(80.3-T_f)^0C$ = Depression in freezing point

i= vant hoff factor = 1 (for non electrolyte such as nitrobenzene)

$K_f$ = freezing point constant = $7.45^0C/m$

m= molality  = 0.765

$(80.3-T_f)^0C=1\times 7.45\times 0.765$

$T_f=74.6^0C$

Thus the freezing point of a 0.765 m solution of nitrobenzene in naphthalene is $74.6^0C$