Wize High School Grade 12 Chemistry Textbook > Acids and Bases
Conjugate Acid-Base Pairs
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Identifying Conjugate Acid and Base Pairs
Two substances that differ from each other only by one proton (H+) are referred to as a conjugate acid-base pair.
Identify the acid, base, conjugate acid, and conjugate base in the following reactions:
1) HNO2(aq) + H2O(l) ⇌ H3O+(aq) + NO2-(aq)
acid base conj. acid conj. base
Write the Ka or Kb expression for this reaction:
- If we were to increase Ka, would that lead to more/less dissociation into ions?More
- Would this mean we have a stronger/weaker acid?Stronger
2) NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq)
base acid conj. acid conj. base
Write the Ka or Kb expression for this reaction:
- If we were to increase Kb, would that lead to more/less OH- ions?more
- Would we have a stronger/weaker base?stronger
Practice: Conjugate Acid-Base Pairs
In the reaction HSO4-(aq) + OH-(aq) ⇌ SO42-(aq) + H2O(l), the conjugate acid-base pairs are:
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Determine the conjugate acids for each of the following:
1. H2O
2. HCO3-
3. F-
4. CN-
Determine the conjugate bases for each of the following:
5. HSO4-
6. HCl
7. HOCN
8. CH3COOH
In the reaction:
Choose the pair of substances that are both Brønsted-Lowry bases in the equilibrium reaction.