Magnesium citrate, Mg3(C6H5O7)2, belongs to a class of laxatives called hyperosmotics, which are used for rapid emptying of the bowel. When a concentrated solution of magnesium citrate is consumed, it passes through the intestines, drawing water and promoting diarrhea, usually within 6 hours.

Calculate the osmotic pressure of a magnesium citrate laxative solution containing 27.0 g of magnesium citrate in 252 mL of solution at 37 ∘C (approximate body temperature). Assume complete dissociation of the ionic compound.

1 Answer

  • 4 weeks ago

    π = i M R T

    Calculate the molarity:

    (M) (0.252 L) = 27.0 g / 451.112 g/mol

    M = 0.23751 mol/L

    π = (5) (0.23751 mol/L) (0.08206 L atm / mol K) (310 K)

    π = 30.2 atm

    The 5 for the van 't Hoff factor comes from here:

    Mg3(C6H5O7)2 ---> 3Mg^2+(aq) + 2C6H5O7^3-(aq)

    Each Mg3(C6H5O7)2 that dissolves yield 5 ions in solution.

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