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Calculate the freezing point of an aqueous solution containing 10.5 g of Magnesium bromide in 200 g of water, assuming complete dissociation of Magnesium bromide. [Molar mass of Magnesium bromide = 184 g "mol"^(-1), K_f, for water = 1.86 K kg "mol"^(-1) ?] |
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Answer» SOLUTION :Number of moles of `MgBr_2`= 10.5/184 =0.0571 mole Molality of the solution` = (0.571)/(200) xx 1000 = 0.2855 m` vant HOFF FACTOR i = 3`[ because MgBr_2 to Mg^(2+)+ 2Br^(-) ]` Applying the relation : ` Delta T_f = iK_f m` Substituting the values, we have ` Delta T_f = 2 xx 1.86 xx 0.2855 = 1.59 K` Freezing POINT of the solution = 273 |
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