CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2011

  • question_answer
    A mixture of ethane and ethene occupies 41 L at 1 atm and 500 K. The mixture reacts completely with\[\frac{10}{3}\]mole of\[{{O}_{2}}\]to produce \[C{{O}_{2}}\]and \[{{H}_{2}}O\]. The mole fraction of ethane and ethene in the mixture are respectively (R = 0.082 L atm\[{{K}^{-1}}mo{{l}^{-1}}\])

    A)  0.50, 0.50        

    B)         0.75, 0.25

    C)  0.67, 0.33         

    D)         0.25, 0.75

    E)  0.33, 0.67

    Correct Answer: C

    Solution :

    For a gaseous mixture of\[{{C}_{2}}{{H}_{6}}\]and\[{{C}_{2}}{{H}_{4}}\] \[pV=nRT\] or            \[n=\frac{PV}{RT}=\frac{1\times 41}{0.082\times 500}\] or            \[n=1\] \[\therefore \]Total mole of\[{{C}_{2}}{{H}_{6}}+{{C}_{2}}{{H}_{4}}=1\]mole Let the mole of\[{{C}_{2}}{{H}_{6}}=x\] then mole of \[{{C}_{2}}{{H}_{4}}=1-x\] \[{{C}_{2}}{{H}_{6}}+\frac{7}{2}{{O}_{2}}\xrightarrow{{}}2C{{O}_{2}}+3{{H}_{2}}O\] \[{{C}_{2}}{{H}_{4}}+3{{O}_{2}}\xrightarrow{{}}2C{{O}_{2}}+2{{H}_{2}}O\] \[\therefore \]Mole of\[{{O}_{2}}\]needed for complete reaction of mixture                                 \[=\frac{7}{2}x+3(1-x)\] \[\therefore \]  \[\frac{7}{2}x+3(1-x)=\frac{10}{3}\] Or           \[x=\frac{2}{3}\] Thus, mole fraction of\[{{C}_{2}}{{H}_{6}}=\frac{2}{3}=0.67\] and mole fraction of\[{{C}_{2}}{{H}_{4}}=1-\frac{2}{3}=0.33\]


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