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Ethylene glycol (molar mass = 62 g "mol"^(-1)) is a common automobile antifreeze. Calculate the freezing point of a solution containing 12.4 g of this substance in 100 g of water. Would it be advisable to keep this substance in the car radiator during summer ? Given : K_f for water = 1.86 K kg/mol, K_bfor water = 0.512 K kg/mol. |
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Answer» SOLUTION :(i)Molality of the solution (m) = ` = (12.4 xx 1000)/(62 xx 100) = 2` ` Delta T_f = K_f xx m = 1.86 xx 2 = 3.72 K` Freezing point of the solution = 273.15 K - 3.72 K = 269.43 K (ii) `Delta T_b = K_bxx m = 0.512 xx 2 = 1.024 K` Boiling point of the solution = 373 K + 1.024 K = 374.02 K Yes, it is ADVISABLE to KEEP this SUBSTANCE in the car radiator during summer. |
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