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BVP Medical BVP Medical Solved Paper-2007

  • question_answer
    If 20 g of a solute was dissolved in 500 mL of water and osmotic pressure of the solution was found to be 600 mm of Hg at \[{{15}^{o}}C\], then molecular weight of the solute is

    A)  1000                                     

    B)  1200

    C)  1400                                     

    D)  1800

    Correct Answer: B

    Solution :

                    Key Idea: Osmotic pressure is colligative property. Use the formula \[\pi V=nRT\] to solve problem. \[\pi V=nRT\]                 or            \[\pi =\frac{n}{V}RT=\frac{m\,RT}{MV}\] where \[\pi \] = osmotic presure = 600 mm of Hg \[=600/760\text{ }atm\] m = mass of solute = 20 g M = molecular mass of solute R = 0.0821 L atm \[mo{{l}^{-1}}\text{ }{{K}^{-1}}\] \[T={{15}^{o}}C=15+273=288\text{ }K\] \[V=500mL=0.5L\] \[\frac{600}{760}=\frac{20\times 0.0821\times 288}{M\times 0.5}\] or            \[M=1200\] \[\therefore \] Molecular mass of solute is 1200.


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