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JEE Main & Advanced Chemistry Thermodynamics / रासायनिक उष्मागतिकी Question Bank Mock Test - Chemical Thermodynamics

  • question_answer
    \[{{C}_{2}}{{H}_{6}}(g)+3.5{{O}_{2}}(g)\to 2C{{O}_{2}}(g)+3{{H}_{2}}O(g)\]\[\Delta {{S}_{vap}}({{H}_{2}}O,\ell )={{x}_{1}}cal\,{{K}^{-1}}\] (boiling point = \[{{T}_{1}}\]) \[\Delta {{H}_{f}}({{H}_{2}}O,\ell )={{x}_{2}}\] \[\Delta {{H}_{f}}({{C}_{2}}O,)={{x}_{2}}\] \[\Delta {{H}_{f}}({{C}_{2}}{{H}_{6}},)={{x}_{4}}\] Hence, \[\Delta H\] for the reaction is

    A)  \[2{{x}_{3}}+3{{x}_{2}}-{{x}_{4}}\]

    B)  \[2{{x}_{3}}+3{{x}_{2}}-{{x}_{4}}+3{{x}_{1}}{{T}_{1}}\]

    C)  \[2{{x}^{+}}+3{{x}_{2}}-{{x}_{4}}+3{{x}_{1}}{{T}_{1}}\]

    D)  \[{{x}_{1}}{{T}_{1}}+{{x}_{2}}+{{x}_{3}}-{{x}_{4}}\]

    Correct Answer: B

    Solution :

    [b]  \[{{H}_{2}}O(l)\to {{H}_{2}}O(g)\Delta {{H}_{vap}}=\Delta {{S}_{vap}}{{T}_{B.P.}}={{x}_{1}}{{T}_{1}}\] \[\Delta {{H}_{f}}({{H}_{2}}O,g)=\Delta {{H}_{f}}({{H}_{2}}O,1)+\Delta {{H}_{vap}}={{x}_{2}}+{{x}_{1}}{{T}_{1}}\] \[\Delta {{H}_{reaction}}=2\Delta {{H}_{f}},(C{{O}_{2}},g)+3\Delta {{H}_{f}}({{H}_{2}}O,g)-\Delta {{H}_{f}}({{C}_{2}}{{H}_{6}},g)\] \[=2{{x}_{3}}+3({{x}_{2}}+{{x}_{1}}{{T}_{1}})-{{x}_{4}}=2{{x}_{3}}+3{{x}_{2}}+3{{x}_{1}}{{T}_{1}}-{{x}_{4}}\]


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