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ser-zykov [4K]
3 years ago
7

Pure nitrobenzene freezes at 5.67 C. When 1.0g of ethanol (C2H6O) is mixed with 20.0g nitrobenzene, the freeze point drops to –0

.53 C. What is the freezing-point depression constant (Kf) of nitrobenzene?
Chemistry
1 answer:
sukhopar [10]3 years ago
5 0

Answer: The freezing-point depression constant (Kf) of nitrobenzene is 5.7^0C/m

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=(5.67-(-0.53)^0C=6.2^0C = Depression in freezing point

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

K_f = freezing point constant = ?

m= molality

\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}

Weight of solvent = 20 g = 0.02 kg

mass of solute (ethanol) = 1.0 g

Molar mass of ethanol = 46 g/mol

6.2=1\times K_f\times \frac{1.0g}{46g/mol\times 0.02kg}

K_f=5.7^0C/m

Thus freezing-point depression constant (Kf) of nitrobenzene is 5.7^0C/m

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