How to identify the acid, base, conjugate acid, and the conjugate base?

Identify the conjugate acid-base pair in the following NH3 + H2O = NH+4 + OH-?

• Answer:

  In order to find the conjugate base of an acid, you take away a H. In order to find the conjugate acid of a base, you add a H. In the equation: NH3 + H2O -> NH4+ + OH- We can see that from NH3 to NH4+, a H is added because it goes from neutral to a charge of +1 (more protons than electrons). We can also see that from H2O to OH-, a H is removed because it goes from 2 H to 1 H. The charge itself goes from neutral to negative (more electrons than protons). So we can say that NH3/NH4+ is the base conjugate acid pair, and H2O/OH- is the acid conjugate base pair.