JEE Main & Advanced Sample Paper JEE Main Sample Paper-27

  • question_answer
    Consider the following equilibrium in a closed container   \[{{N}_{2}}{{O}_{4}}(g)2N{{O}_{2}}(g)\] At a fixed temperature, the volume of the reaction container is halved. For this change, which of the following statements holds true regarding the equilibrium constant \[\mathbf{(}{{\mathbf{K}}_{\mathbf{p}}}\mathbf{)}\] and degree of dissociation \[\mathbf{(}\alpha \mathbf{)}\]?

    A)  neither K nor a changes       

    B)  both K and exchange

    C)  K changes, but a does not change

    D)  K does not change but a changes

    Correct Answer: D

    Solution :

    \[{{N}_{2}}{{O}_{4}}(g)\rightleftharpoons 2N{{O}_{2}}\] Moles t = 0,       1                      0 Molesa at eq.     \[1-\alpha \]                    \[2\alpha \] \[{{K}_{P}}=\,\frac{{{\left( \frac{2\alpha }{(1+\alpha )}\times P \right)}^{2}}}{\frac{1-\alpha }{1+\alpha }\times P}\,=\frac{4{{\alpha }^{2}}}{1-{{\alpha }^{2}}}\times P\] Let total pressure at eq. = P. or         \[{{K}_{P}}=\frac{4{{\alpha }^{2}}}{1-{{\alpha }^{2}}}\times P\] When volume is halved, P is double. \[\therefore \] \[\alpha \] will change as \[{{K}_{p}}\] is independent of pressure change.


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