What are conjugate acid-base pairs?

1 Answer
Apr 14, 2014

All acids have a conjugate base. All bases have a conjugate acid. Acids "donate" #H^(+)# when they react. This is most easily seen when they dissociate in water:

#H_2SO_4# + #H_2O# => #HSO_4^-# + #H_3O^+#

In this example, sulfuric acid (#H_2SO_4#) is an acid because it "donates" #H^+# to the water. It becomes the hydrogen sulfite ion (#HSO_4^-#) which is the conjugate base of sulfuric acid.

The same idea applies to a base:

#NH_3# + #H_2O# <=> #NH_4^+# + #OH^-#

Ammonia (#NH_3#) is a base because is "accepts #H^+# from water to come its conjugate acid, the ammonium ion (#NH_4^+#).

This video gives an overview of acids and bases; the second half is about conjugate pairs:

Simple, easy to understand can be on this site http://www.chemteam.info/AcidBase/Conjugate-Pairs.html