WorksheetAcidsandKaAnswerKey
I)
1)
2)
3)
4)
5)
6)
To write Ka expressions for any of the following which are weak acids follow these steps:
i) Look in the Ka Table to see if it is a weak acid or a strong acid. (We don’t do Ka’s for strong
acids).
ii) If it is a weak acid write a balanced equation to show the acid ionization reaction with water.
iii) Next write the Ka expression for the weak acid.
iv) Using the Ka expression what is the expected [H3O+] at equilibrium for a 1.0 M solution of each
weak acid.
Nitrous acid
Boric acid
Nitric acid
Iodic acid
Hydroiodic acid
Hydrogen Sulphite ion
1. Nitrous Acid (HNO2) Weak acid
Ka = 4.6 × 10–4
[I]
[C]
[E]
1
Ka = 7.3 × 10–10
2. Boric acid (H3BO3) Weak acid
[I]
[C]
[E]
100% ionized
3. Nitric acid (HNO3) Strong acid
4. Iodic Acid (HIO3) Weak acid
[H3O+ ] = original [HNO3] = 1.0 M
Ka = 1.7 × 10–1
[I]
[C]
[E]
2
100% ionized
5. Hydroiodic acid (HI) Strong acid
−
6. Hydrogen sulphite ion ( HSO3 ) Weak acid
[H3O+ ] = original [HI] = 1.0 M
Ka = 1.0 × 10–7
[I]
[C]
[E]
3