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A weak base `(BOH)` with `K_(b) = 10^(-5)` is titrated with a strong acid `(HCl)`, At `3//4` th of the equivalence point, pH of the solution is:A. `5 + "log"3`B. `14-5-"log"3`C. `14-5 + log3`D. `9.523`. |
Answer» Correct Answer - B Let the initial no. of equivalents of `BOH` be x `{:(,BOH+HCl,rarr,BCl+,H_(2)O),("Initial equivalent",x,,0,0),("At"3//4th eqv. pt., x-(3x)/(4),,(3)/(4)x,(3)/(4)x):}` `= x/4` Now solution contains `x/4` moles of weak base and `(3x)/(4)` moles of its conjugated acid which is a basic buffer. `pOH = pK_(b) + "log" (["salt"])/(["Base"]) = 5+ "log" (3x xx 4)/(4 xx x)` `pH = 14 - 5 - log 3 = 8.523` |
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