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

  • question_answer
    If the equilibrium constant of the reaction of weak acid HA with strong base is\[{{10}^{-7}}\], then pOH of the aqueous solution of \[0.1M\text{ }NaA\] is

    A) 8                     

    B) 10

    C) 4                                 

    D) 5

    Correct Answer: C

    Solution :

    [c] Hydrolysis of a salt is reverse reaction of acid-base neutralization reaction. \[\therefore {{K}_{h}}=\frac{{{K}_{w}}}{{{K}_{a}}}=\frac{{{10}^{-14}}}{{{10}^{-7}}}={{10}^{-7}}\] \[[O{{H}^{-}}]=ch=c\times \sqrt{\frac{{{K}_{h}}}{c}}=\sqrt{c\times {{K}_{h}}}=\sqrt{{{10}^{-8}}}={{10}^{-4}}\] \[\Rightarrow pO{{H}^{-}}=-log\left[ O{{H}^{-}} \right]=-\log [{{10}^{-4}}]=4\]


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