JEE Main & Advanced Chemistry Equilibrium / साम्यावस्था Question Bank Self Evaluation Test - Equilibrium

  • question_answer
    The dissociation constants of a weak acid HA and weak base BOH are \[2\times {{10}^{-5}}\] and \[5\times {{10}^{-6}}\] respectively. The equilibrium constant for the neutralisation reaction of the two is

    A) \[1.0\times {{10}^{4}}\]          

    B) \[1.0\times {{10}^{-4}}\]

    C) \[1.0\times {{10}^{-10}}\]        

    D) \[2.5\times {{10}^{-1}}\]

    Correct Answer: A

    Solution :

    [a] \[HA+BOH\rightleftharpoons BA+{{H}_{2}}O\] \[\therefore {{K}_{H}}=\frac{{{K}_{w}}}{{{K}_{a}}\times {{K}_{b}}}.\] The inverse of \[{{K}_{H}}\] is\[{{K}_{c}}=\frac{{{K}_{a}}\times {{K}_{b}}}{{{K}_{w}}}.\] \[=\frac{2\times {{10}^{-5}}\times 5\times {{10}^{-6}}}{1\times {{10}^{-14}}}=1.0\times {{10}^{4}}\]


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