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`18mL` of mixture of `CH_(3)COOH` and `CH_(3)COONa` required `6mL` of `0.1M NaOH` for neutralisation of the acid `12mL` of `0.1M HC1` for reaction with salt, separately. If `pK_(a)` of the acid is `4.75`, what is the `pH` of the mixtureA. `4.5`B. `4.6`C. `4.75`D. `5.05` |
Answer» Correct Answer - D For neutralisation of `CH_(3)COOH` with `NaOH` mmol of `CH_(3)COOH` = mmol of `NaOH` `= 6 xx 0.1 = 0.6` For neutralisation `CH_(3)COONa` with `HC1` mmol of `CH_(3)COONa` mmol of `HC1` `12 xx 0.1 = 1.2` Concentration of acid and slat in `18mL` of mixture `[CH_(3)COOH] = (0.6 "mmol")/(18mL)` `[CH_(3)COONa] = (1.2 "mmol")/(18mL)` `pH = 4.75 + log ((1.2)/(0.6))` `= 4.75 + log 2 = 4.75 + 0.3 = 5.05` |
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