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At `25^(@)C` find pH of resultant solution prepared by mixing 50 ml, 0.2 M kA(aq) and 50 ml, 0.2M kB(aq) solution : (given = `K_(a)(HA)=5xx10^(-9), K_(a)(HB)=1.25xx10^(-9)`)A. 3B. 2.5C. 11D. 6 |
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Answer» Correct Answer - D `"pH of "(NaHCO_(3))=(1)/(2)[pKa_(1)+pKa_(2)]` `(1)/(2)[pKa_(1)+pKa_(2)]=9` `pKa_(1)+underset(LR)(pKa_(2))=18` `H_(2)CO_(3)+NaOH rarr NaHCO_(3)` `{:(44,40,,-),(4,0,,40):}` Buffer `rarr pH = pKa_(1)+log.(40)/(4)` `pH=pKa_(1)+log.(40)/(4)` `pH=pKa_(1)+log10` `7.6 = pKa_(1)+1` `pk_(a_(1))=6.6` `18=6.6 + pk_(a_(2))` `pk_(a_(2))=11.4` |
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