How can I identify conjugate acids and bases?
Here is one answer.
See this Socratic answer.
And here's another way to look at it.
A conjugate acid contains one more H atom and one more + charge than the base that formed it.
A conjugate base contains one less H atom and one more - charge than the acid that formed it.
Let us take the example of bicarbonate ions reacting with water to create carbonic acid and hydronium ions.
HCO₃⁻ + H₂O → H₂CO₃ + OH⁻
base + acid → Conj A + Conj B
We see that HCO₃⁻ becomes H₂CO₃. It has one more H atom and one more + charge (-1 + 1 = 0). So H₂CO₃ is the conjugate acid of HCO₃⁻.
The H₂O becomes OH⁻. It has one less H atom and one more – charge. So OH⁻ is the conjugate base of H₂O.