Chemistry Year 12 - Module 6 - Lesson 9
pH of Weak Acids & Bases — Ka, Kb & ICE Tables
1. Key Ideas
Aspirin (acetylsalicylic acid) has Ka = 3.0 × 10⁻⁴ — and the ICE table you will build in this lesson predicts exactly how much H⁺ aspirin releases in your stomach, why it irritates the gastric lining, and why enteric-coated tablets dissolve in the intestine instead.
- ICE tables track Initial, Change, and Equilibrium concentrations
- Why weak acids require ICE tables while strong acids do not
2. Success Criteria
By the end, you should be able to:
- ICE tables track Initial, Change, and Equilibrium concentrations
- The simplifying assumption [HA]initial − x ≈ [HA]initial is valid when Ka/c < 0.0025
- Kb = Kw/Ka for conjugate acid-base pairs
3. Key Terms
4. Activity: Build the Lesson Map
Use the lesson to complete the table. Keep answers brief but specific.
| Prompt | Your answer |
|---|---|
| Main concept | |
| Important example | |
| Common mistake to avoid | |
| How this links to the next lesson |
5. Short Answer Questions
1. Explain this lesson goal in your own words: "ICE tables track Initial, Change, and Equilibrium concentrations". Use one specific example from the lesson.
2. Apply this idea to a new example: "The simplifying assumption [HA]initial − x ≈ [HA]initial is valid when Ka/c < 0.0025". Show your reasoning clearly.
3. Analyse why this idea matters for understanding pH of Weak Acids & Bases — Ka, Kb & ICE Tables: "Kb = Kw/Ka for conjugate acid-base pairs".
6. Extend: Apply the Idea
A student gives a memorised answer about pH of Weak Acids & Bases — Ka, Kb & ICE Tables but does not use evidence or reasoning.
Improve the answer by writing a stronger response that uses accurate terminology, a relevant example and a clear explanation.
7. Multiple Choice
1. What is the best first step when answering a question about pH of Weak Acids & Bases — Ka, Kb & ICE Tables?
A. Identify the key concept being tested
B. Write every fact from memory
C. Ignore the command word
D. Skip examples and evidence
2. Which answer would show stronger understanding of pH of Weak Acids & Bases — Ka, Kb & ICE Tables?
A. An answer with accurate terms and reasoning
B. A copied definition only
C. A single-word response
D. An answer with no example
3. What should you do if a question asks you to explain?
A. Link the idea to a reason or cause
B. List unrelated facts
C. Only draw a diagram
D. Write the shortest possible answer
8. Success Criteria Proof
Finish with evidence that you can do each success criterion.