# The melting point of camphor is 177.5 degree Celsius while that of a mixture of one gram naphthalene  and 10 gram of camphor is 147 degree Celsius,

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The melting point of camphor is 177.5 degree Celsius while that of a mixture of one gram naphthalene  and 10 gram of camphor is 147 degree Celsius, calculate the cryoscopy constant of camphor.

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Cryoscopic constant is the depression of the freezing point of the solvent produced on dissolving are mole of substance in 1000g of it. it is also called molal depression constant. it is denoted by Kf.

As we know,

depression in freezing point

△Tf = Kf m

where,

m = molality

Kf = Cryoscopic constant

△T= depression in freezing point

we have given

△T= 177.5 - 147

= 30.5 °C

Number of moles of  Naphthalene = $\frac1{128}$ mole

molality = $\cfrac{\frac1{128}}{10}\times1000$

= 0.78 m

Therefore,

Kf$\frac{30.5}{0.78}$

Kf = 39.1 °C kg mol-1

Hence, the cryosopic constant will be 39.1 °C kg mol-1