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A weak base `BOH` is titrated with strong acid `HA`. When `10mL` of `HA` is added, the `pH` is `9.0` and when `25mL` is added, `pH` is `8.0`. The volume of acid required to reach the equivalence point isA. `50mL`B. `40mL`C. `35mL`D. `30mL` |
Answer» Correct Answer - D `{:(BOH+,HArarr,BA+H_(2)O,,),(W_(B),S_(A),("Salt of" W_(B)//S_(A)),,):}` `[W_(B)` is in excess, so basic buffer is formed] `pOH = pK_(b) + "log" ([BA])/([BOH]) (pH = 9, pOH = 14 - 9 = 5)` `5 = pK_(b) + log ((10)/(V - 10)) …(i)` When `pH = 8, :. pOH = 14 - 8 = 6`. `6 = pK_(b) + log ((25)/(V - 25))` Solve equation (i) and (ii), `V = 30mL`. |
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