Chemistry Year 12 - Module 7 - Lesson 18

Organic Acids & Bases — pKa, Strength & Reactions

Use this worksheet after reading the lesson to practise the key ideas and prove you can meet the success criteria.

Name

Date

Class

1. Key Ideas

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pKa values for carboxylic acids (~5), phenols (~10), alcohols (~16)
How resonance stabilisation of conjugate base determines pKa

2. Success Criteria

By the end, you should be able to:

pKa values for carboxylic acids (~5), phenols (~10), alcohols (~16)
Kb values for alkylamines, arylamines, amides
Diagnostic reactions: NaHCO₃, Na₂CO₃, NaOH, Na metal

3. Key Terms

lower pKa = stronger acidA substance that donates protons (H⁺) or accepts electron pairs, according to context.

PrincipleIf a system at equilibrium is disturbed, it will shift to minimise the disturbance.

HydrocarbonAn organic compound containing only carbon and hydrogen atoms.

Functional groupA specific atom arrangement determining characteristic chemical reactions.

Homologous seriesA family of compounds with the same functional group, differing by CH₂.

Addition polymerA polymer formed by monomers adding together without loss of atoms.

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: "pKa values for carboxylic acids (~5), phenols (~10), alcohols (~16)". Use one specific example from the lesson.

Band 32 marks

2. Apply this idea to a new example: "Kb values for alkylamines, arylamines, amides". Show your reasoning clearly.

Band 43 marks

3. Analyse why this idea matters for understanding Organic Acids & Bases — pKa, Strength & Reactions: "Diagnostic reactions: NaHCO₃, Na₂CO₃, NaOH, Na metal".

Band 54 marks

6. Extend: Apply the Idea

Band 5/65 marks

A student gives a memorised answer about Organic Acids & Bases — pKa, Strength & Reactions 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 Organic Acids & Bases — pKa, Strength & Reactions?

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 Organic Acids & Bases — pKa, Strength & Reactions?

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.

Success criterion 1

Prove that you can: pKa values for carboxylic acids (~5), phenols (~10), alcohols (~16)