When 6.13 g of a certain molecular compound X are dissolved in 90. g of formamide (NH2COH), the freezing point of the solution is measured t

Question

When 6.13 g of a certain molecular compound X are dissolved in 90. g of formamide (NH2COH), the freezing point of the solution is measured to be 2.1 °C. Calculate the molar mass of X. If you need any additional information on formamide, use only what you find in the ALEKS Data resource. Also, be sure your answer has a unit symbol, and is rounded to the correct number of significant digits.

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Nem 3 years 2021-08-13T13:52:18+00:00 1 Answers 8 views 0

Answers ( )

  1. dangkhoa
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    2021-08-13T13:53:43+00:00
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    Answer:

    321.6 g/Mol

    Explanation:

    mass of solvent in kilograms = 90g/1000 = 0.09 Kg

    Given that;

    ΔTf = Kf . m . i

    Where;

    Kf = freezing point constant = 4.25 °C/Kg mol

    m = molality of the solution

    i = Van’t Hoff factor = 1 (since the substance is molecular)

    ΔTf = freezing point of pure solvent – freezing point of solution

    freezing point of pure solvent = 3 °C

    ΔTf = 3 °C – 2.1 °C

    ΔTf = 0.9  °C

    0.9= 4.25 * 6.13/M/0.09 * 1

    0.9= 26.0525/M * 1/0.09

    0.9 = 26.0525/0.09 M

    0.9 * 0.09M = 26.0525

    M = 26.0525/0.9 * 0.09

    M= 321.6 g/Mol

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