posted by Samantha .
4.The Kb of ammonia, NH3, is 1.8x10^-5. What is the pH of a 2.000 millimolar solution of ammonia , to 3 significant digits.
NH3 + HOH ==> NH4^+ + OH^-
Kb = (NH4^+)(OH^-)/(NH3)
Set up and ICE chart, substitute and solve for OH, then convert to pOH and to pH.