For the titration of 20.00 mL of 0.375 M pyridine using 0.150 M HBr, what is...

Question

Question

For the titration of 20.00 mL of 0.375 M pyridine using 0.150 M HBr, what is the pH after 30.00 mL of HBr has been added?

science chemistry

Answer 1

Answer #1

pKa of pyridine = 5.23

millimoles of pyridine = 20 x 0.375 = 7.5

millimoles of HBr = 0.150 x 30 = 4.5

C5H5N + HBr -----------------------------> C5H5NH+ + Br-

7.5 4.5 0 0

3 0 4.5 0

pH = pKa + log [C5H5N / C5H5NH+]

pH = 5.23 + log (3 / 4.5)

pH = 5.05

note : if anything goes wrong. please check your Kb value with my Kb value 1.7×10^–9

Answer 2

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