BCECE Medical BCECE Medical Solved Papers-2014

  • question_answer
    A buffer solution contains 0.1 mole of sodium acetate in \[1000\,\,c{{m}^{3}}\] of 0.1 M acetic acid. To the above buffer solution, 0.1 mole of sodium acetate is further added and dissolved. The pH of the resulting buffer is equal to

    A)  \[p{{K}_{a}}-\log 2\]

    B)  \[p{{K}_{a}}\]

    C)  \[p{{K}_{a}}+2\]

    D)  \[p{{K}_{a}}+\log 2\]

    Correct Answer: D

    Solution :

    Initially \[[C{{H}_{3}}COONa]=0.1\,\,mol\] \[[C{{H}_{3}}COOH]=0.1\,\,mol\] When \[0.1\,\,mol\,\,C{{H}_{3}}COONa\] is added. \[[C{{H}_{3}}COONa]=0.1+0.1=0.2\,mol\]                 \[pH=p{{K}_{a}}+\log \frac{[salt]}{[acid]}\] \[=p{{K}_{a}}+\log \frac{0.2}{0.1}=p{{K}_{a}}+\log \,2\]


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