9. For a n acid, HA, the concentrations of HA and A are 0.1M and 0.02...

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science chemistry

Answer 1

Answer #1

Given pH =4.0 & conc of A^- =0.02 M , conc of HA = 0.1 M

So according to Henderson hasselbalch equation

pH=pKa + log [A^- / HA]

4.0 = pKa + log [ 0.02 / 0.1 ]

4.0 = pKa + log [ 0.2 ]

4.0 = pKa -0.699

pKa = 4.0 + 0.699

pKa = 4.699

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Answer 2

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