A 4.305-g sample of a nonelectrolyte is dissolved in 105 g of water. the solution freezes at -1.23c. calculate the molar mass of the solute.

Question

A 4.305-g sample of a nonelectrolyte is dissolved in 105 g of water. the solution freezes at -1.23c. calculate the molar mass of the solute. kf for water = 1.86c/m.

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2022-04-10T14:35:15+00:00 0 Answers 0

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  1. Audrey
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    2022-04-10T14:37:00+00:00
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    The answer is 62.00 g/mol.
    Solution:
    Knowing that the freezing point of water is 0u00b0C, temperature change u0394t is
    u0394t = 0C – (-1.23u00b0C) = 1.23u00b0C
    Since the van ‘t Hoff factor i is essentially 1 for non-electrolytes dissolved in water, wecalculate for the number of moles x of the compound dissolved from the equation
    u0394t = i Kf m
    1.23u00b0C = (1) (1.86u00b0C kg mol-1) (x / 0.105 kg)
    x = 0.069435 mol
    Therefore, the molar mass of the solute is
    molar mass = 4.305g / 0.069435mol = 62.00 g/mol

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