[jmg12]

Nicotine, C10H14N2, has two basic nitrogen atoms and both can react with water.

Nic + H2O ---> NicH⁺ + OH-

NicH+ + H2O ---> NicH₂ ²⁺ + OH-

Kb1 = 7.0 x 10^-7
Kb2 = 1.1 x 10^-10
Calculate the pH of a 0.020 M solution.

I did it by only using the first equation and Kb1. How do you include Kb2 or do you not have to?

[Borek]

http://www.chembuddy.com/?left=pH-calculation&right=pH-polyprotic-acid-base

http://www.chembuddy.com/?left=pH-calculation&right=pH-polyprotic-simplified

These pages are about acids, but for bases the derivation is identical, it will be just about calculation of pOH which in the end you can convert to pH.