NEET AIPMT SOLVED PAPER SCREENING 2011

  • question_answer
    In Duma's method of estimation of nitrogen 0.35 g of an organic compound gave 55 mL of nitrogen collected at 300 K temperature and 715 mm pressure. The percentage composition of nitrogen in the compound would be (Aqueous tension at 300 K = 15 mm)

    A)  16.45       

    B)                         17.45   

    C)         14.45                   

    D)         15.45

    Correct Answer: A

    Solution :

    \[\frac{{{p}_{1}}{{V}_{1}}}{{{T}_{1}}}=\frac{{{p}_{2}}{{V}_{2}}}{{{T}_{2}}}\] Where,\[{{p}_{2}}=\] pressure of \[{{N}_{2}}\] at STP = 760 mm \[{{T}_{2}}\]=Temperature of \[{{N}_{2}}\] at STP = 273 K \[{{V}_{2}}\]? Volume of \[{{\text{N}}_{\text{2}}}\] at STP (By gas equation) \[\left( \frac{\rho -{{\rho }_{1}}}{t+273} \right){{V}_{1}}\times \frac{273}{760}={{V}_{2}}\]where,\[{{\rho }_{1}}=\rho -{{\rho }_{1}}\] \[\rho =715\,\text{mm}\](pressure at which \[{{\text{N}}_{\text{2}}}\] collected). \[{{\rho }_{1}}=\] aqueous tension of water = 15 mm \[{{T}_{1}}=t+273=300K\] \[{{V}_{1}}=55\,mL=\] volume of moist nitrogen in nitro meter \[\therefore \]\[{{V}_{2}}=\frac{(715-15)\times 55}{300}\times \frac{273}{760}=46.098\,mL\] % of nitrogen in given compound \[=\frac{28}{22400}\times \frac{{{V}_{2}}}{W}\times 100=\frac{28}{22400}\times \frac{46.098}{0.35}\times 100\] \[=16.4%\]


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