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    Osmotic Pressure moles NaCl exist as ion pairs

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    An aqueous solution is 1.00% NaCl by mass and has a density of 1.071 g/cm3 at 25°C. The observed osmotic pressure of this solution is 7.83 atm at 25°C.

    (a) What fraction of the moles of NaCl in this solution exist as ion pairs?
    %
    (b) Calculate the freezing point that would be observed for this solution.
    °C

    © BrainMass Inc. brainmass.com April 3, 2020, 7:53 pm ad1c9bdddf
    https://brainmass.com/chemistry/stoichiometry/osmotic-pressure-moles-nacl-exist-ion-pairs-286851

    Solution Preview

    density = 1.071 g/cm3 = 1.071 kg/L
    molar mass of NaCl = 23 + 35.45 = 58.45 g/mol
    Kf of water = 1.86 C/m ---from book
    pi = osmotic pressure

    Basis : 1 kg of solution

    V = vol. of solution = 1 kg / 1.071 kg/L = 0.9337 L

    M = molarity = mol NaCl / liter solution

    mol NaCl = 0.01(1 kg) (1000g/ 1 kg) ( 1 mol / 58.45 g/mol)
    = 0.171 mol

    M = 0.171 mol / 0.9337 L
    = 0.183 M

    pi = iMRT
    i = pi / MRT
    i ...

    Solution Summary

    The expert examines osmotic pressure moles NaCl exists as ion pairs.

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