J & K CET Medical J & K - CET Medical Solved Paper-2008

  • question_answer
    \[\Delta H\]for the reaction, \[C(graphite)+2{{H}_{2}}(g)\xrightarrow{{}}C{{H}_{4}}(g)\,at\,298K\] and 1 atm is - 17900 cal. The\[\Delta E\]for the above conversion would be

    A)  \[-17900\text{ }cal\]    

    B) \[17900\text{ }cal\]

    C) \[17308\text{ }cal\]        

    D)  \[-17308\text{ }cal\]

    Correct Answer: D

    Solution :

                    \[C(graphite)+2{{H}_{2}}(g)\xrightarrow{{}}C{{H}_{4}}(g);\] \[\Delta H=-17900\text{ }cal\] \[\Delta E=?\] \[\Delta H=\Delta E+\Delta {{n}_{g}}RT\] where,\[\Delta {{n}_{g}}=\]number of moles of gaseous products\[-\]number of moles of gaseous reactants \[=1-2\] \[=-1\] \[\therefore \]  \[\Delta H=\Delta E-1\times R\times T\] \[-17900=\Delta E-1\times 298\times 2\] \[\Delta E=-17900+596\] \[\therefore \]  \[\Delta E=-17304\text{ }cal\]


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