JEE Main & Advanced Chemistry Equilibrium Question Bank Common ion effect, Isohydric solutions, Solubility product, Ionic product of water and salt hydrolysis

  • question_answer 0.5 M ammonium benzoate is hydrolysed to 0.25 percent, hence its hydrolysis constant is            [MH CET 2004]

    A)                 \[2.5\times {{10}^{-5}}\]              

    B)                 \[1.5\times {{10}^{-4}}\]

    C)                 \[3.125\times {{10}^{-6}}\]         

    D)                 \[6.25\times {{10}^{-4}}\]

    Correct Answer: C

    Solution :

               \[{{C}_{6}}{{H}_{5}}COON{{H}_{4}}\to {{C}_{6}}{{H}_{5}}CO{{O}^{-}}+NH_{4}^{+}\]                    \[0.5-\frac{.25}{100}\]  \[\frac{.25}{100}\] \[\frac{.25}{100}\]                    According to Ostwald dilution law.                    \[K=\frac{{{\alpha }^{2}}C}{1-\alpha }\]                                         \[\left( \therefore \ \ \alpha =\frac{.25}{100} \right)\]                    \[K={{\alpha }^{2}}C\]                 \[\left( \because \ \ 1-\alpha =\text{Very small} \right)\]                                 \[K=\frac{.25}{100}\times \frac{.25}{100}\times .5\] ; \[K=3.125\times {{10}^{-6}}\]

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