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What indicator should be used for the titration of 1.0M KH_(2)BO_(2) with 1.10M HCI? |
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Answer» Solution :`H_(2)BO_(3)^(Θ) + H_(3)O^(o+) rarr H_(3)BO^(3) + H_(2)O` At equivalence point, `0.05 M H_(3)BO_(3)` would be produced. Only the first IONISATION step of `H_(3)BO_(3)` is important to the `pH`. `H_(2)BO_(3)^(Θ) + H_(2)O rarr H_(2)BO_(3)^(Θ) + H_(3)O^(o+)` `K_(a) = ([H_(3)O^(o+)][H_(2)BO_(3)^(o+)])/([H_(3)BO_(3)]) =(x^(2))/(0.050) = 7.3 XX 10^(-10)` Thus `x = 6.0 xx 10^(-6)` and `pH = 5.22` `pH 5.22` is in the middle of the range of methy`1` red which would thereofre be SUITABLE. |
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