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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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Answer» 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 △Tf = depression in freezing point we have given △Tf = 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 |
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