Homeschool Guide: These lesson plans are a guide for parents. Content may contain errors — always cross-reference with official exam board specifications.

C22: Reversible Reactions And Equilibrium

FoundationHigherAll Boards

4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.

Fastmail

Lesson Overview

Total Lessons: 4
Tier: Foundation and Higher
Duration: 50 minutes per lesson (200 minutes total)
Exam Boards: AQA, Edexcel, OCR, CCEA

Learning Objectives

Prerequisites

Materials & Equipment

Lesson 1: Introduction: Reversible Reactions And Equilibrium

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

3 quick questions to activate prior knowledge about reversible reactions and equilibrium. Use mini-whiteboard or paper.

Main Content (35 minutes)

Parent/Teacher Guide:
Before lesson: Read script below. Prepare materials. Pre-teach key vocab: Reversible Reactions And Equilibrium.
If stuck: See Troubleshooting below. Break into smaller steps.
Extension: See Stretch & Challenge section.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: Reversible Reactions And Equilibrium. Goal: by the end you can in a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions, using the method shown step by step. Connects to the previous lesson in this unit because you'll reuse its method throughout today's work."
Mins 5-15 - Direct Instruction: 1) Define: "Reversible Reactions And Equilibrium is..." 2) Key principle: "Most important:..." 3) Draw diagram, label live. 4) Real example: "Like In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions. - a real example worked through in full..."
Mins 15-25 - Guided Practice: Ex1: Teacher models. Ex2: Student tries with guidance. Ex3: Student independent.
Mins 25-35 - Independent Practice: 3-5 questions. Immediate feedback.
Worked Example 1: Basic

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. What is asked? In
  2. Recall knowledge:
  3. Apply: Heating drives the forward reaction (decomposition — endothermic). Cooling drives the backward reaction (reformation — exothermic). Observation: white solid disappears on heating (produces two gases) and reappears on cooling.
  4. Check: Check the units named in the question and sense-check the size of your answer.
  5. Answer: State the complete final answer.

Tip: "Show working - method marks > answer marks."

Worked Example 2: Multi-step

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. Break down: Separate parts?
  2. Solve each: Heating drives the forward reaction (decomposition — endothermic). Cooling drives the backward reaction (reformation — exothermic). Observation: white solid disappears on heating (produces two gases) and reappears on cooling.
  3. Combine: The parts chain: each answer feeds the next step of the question.
  4. Final answer: Evidence cited from the lesson content.
Worked Example 3: Data/Application

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. Read data: Axes, units, scale
  2. Patterns: Trends, anomalies
  3. Explain: Why? Using reversible reactions and equilibrium
  4. Conclude: Evidence-based

Common Questions & Troubleshooting

Q: "Why does Reversible Reactions And Equilibrium work this way?"
A: Analogy: "In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.". Try re-draw or re-write the worked example from memory, then check it against the model answer.
Q: "Wrong answers on calculations."
A: Checklist: units? formula? calculator mode? sig figs?
Q: "Can't remember key terms."
A: Flashcards (term front, def+diagram back). Spaced repetition: day 1, 3, 7.
Q: "Exam wording confuses me."
A: Commands: Describe=what you see; Explain=reasons; Evaluate=pros/cons+judgement; Calculate=working+units.
Q: "Running out of time."
A: 1 mark/min. Skip hard, return. Attempt all - partial marks count.

Assessment & Model Answers

Mastery Checklist:
  • [ ] Define Reversible Reactions And Equilibrium in own words
  • [ ] Identify features in diagram
  • [ ] Explain process step-by-step
  • [ ] Apply to unfamiliar context
  • [ ] Score 80%+ on past paper question

Model Answer: Past Paper Question

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  • 1 mark: [Key terminology]
  • 1 mark: [Mechanism/process]
  • 1 mark: [Application/example]
  • 1 mark: [Evaluation - Higher]

Model response: "[Complete answer with expected detail/terminology]"

Why full marks: [What makes this strong]

Stretch & Challenge (Grade 8-9):
  • Synoptic links: Connect to C21-rate-of-reaction / the next lesson
  • Real-world: Research use in industry, medicine or research
  • Advanced calc: Try a more challenging variant
  • Critical: "Evaluate limitations of today's model"
  • Research: Recent discovery on reversible reactions and equilibrium, summarise 100 words

Plenary (5 mins)

Label the Diagram

Unlabelled diagram - write all parts in 1 min

Assessment Criteria

Lesson 2: Core Concepts: Reversible Reactions And Equilibrium

Duration: 50 minutes

Starter Activity (5 minutes)

Review Previous Lesson

Quick recap: write 3 key points from last lesson on reversible reactions and equilibrium. Use mini-whiteboard or paper.

Main Content (35 minutes)

Parent/Teacher Guide:
Before lesson: Read script below. Prepare materials. Pre-teach key vocab: Reversible Reactions And Equilibrium.
If stuck: See Troubleshooting below. Break into smaller steps.
Extension: See Stretch & Challenge section.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: Reversible Reactions And Equilibrium. Goal: by the end you can in a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions, using the method shown step by step. Connects to the previous lesson in this unit because you'll reuse its method throughout today's work."
Mins 5-15 - Direct Instruction: 1) Define: "Reversible Reactions And Equilibrium is..." 2) Key principle: "Most important:..." 3) Draw diagram, label live. 4) Real example: "Like In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions. - a real example worked through in full..."
Mins 15-25 - Guided Practice: Ex1: Teacher models. Ex2: Student tries with guidance. Ex3: Student independent.
Mins 25-35 - Independent Practice: 3-5 questions. Immediate feedback.
Worked Example 1: Basic

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. What is asked? In
  2. Recall knowledge:
  3. Apply: Heating drives the forward reaction (decomposition — endothermic). Cooling drives the backward reaction (reformation — exothermic). Observation: white solid disappears on heating (produces two gases) and reappears on cooling.
  4. Check: Check the units named in the question and sense-check the size of your answer.
  5. Answer: State the complete final answer.

Tip: "Show working - method marks > answer marks."

Worked Example 2: Multi-step

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. Break down: Separate parts?
  2. Solve each: Heating drives the forward reaction (decomposition — endothermic). Cooling drives the backward reaction (reformation — exothermic). Observation: white solid disappears on heating (produces two gases) and reappears on cooling.
  3. Combine: The parts chain: each answer feeds the next step of the question.
  4. Final answer: Evidence cited from the lesson content.
Worked Example 3: Data/Application

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. Read data: Axes, units, scale
  2. Patterns: Trends, anomalies
  3. Explain: Why? Using reversible reactions and equilibrium
  4. Conclude: Evidence-based

Common Questions & Troubleshooting

Q: "Why does Reversible Reactions And Equilibrium work this way?"
A: Analogy: "In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.". Try re-draw or re-write the worked example from memory, then check it against the model answer.
Q: "Wrong answers on calculations."
A: Checklist: units? formula? calculator mode? sig figs?
Q: "Can't remember key terms."
A: Flashcards (term front, def+diagram back). Spaced repetition: day 1, 3, 7.
Q: "Exam wording confuses me."
A: Commands: Describe=what you see; Explain=reasons; Evaluate=pros/cons+judgement; Calculate=working+units.
Q: "Running out of time."
A: 1 mark/min. Skip hard, return. Attempt all - partial marks count.

Assessment & Model Answers

Mastery Checklist:
  • [ ] Define Reversible Reactions And Equilibrium in own words
  • [ ] Identify features in diagram
  • [ ] Explain process step-by-step
  • [ ] Apply to unfamiliar context
  • [ ] Score 80%+ on past paper question

Model Answer: Past Paper Question

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  • 1 mark: [Key terminology]
  • 1 mark: [Mechanism/process]
  • 1 mark: [Application/example]
  • 1 mark: [Evaluation - Higher]

Model response: "[Complete answer with expected detail/terminology]"

Why full marks: [What makes this strong]

Stretch & Challenge (Grade 8-9):
  • Synoptic links: Connect to C21-rate-of-reaction / the next lesson
  • Real-world: Research use in industry, medicine or research
  • Advanced calc: Try a more challenging variant
  • Critical: "Evaluate limitations of today's model"
  • Research: Recent discovery on reversible reactions and equilibrium, summarise 100 words

Plenary (5 mins)

Label the Diagram

Unlabelled diagram - write all parts in 1 min

Assessment Criteria

Lesson 3: Application: Reversible Reactions And Equilibrium

Duration: 50 minutes

Starter Activity (5 minutes)

Review Previous Lesson

Quick recap: write 3 key points from last lesson on reversible reactions and equilibrium. Use mini-whiteboard or paper.

Main Content (35 minutes)

Parent/Teacher Guide:
Before lesson: Read script below. Prepare materials. Pre-teach key vocab: Reversible Reactions And Equilibrium.
If stuck: See Troubleshooting below. Break into smaller steps.
Extension: See Stretch & Challenge section.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: Reversible Reactions And Equilibrium. Goal: by the end you can in a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions, using the method shown step by step. Connects to the previous lesson in this unit because you'll reuse its method throughout today's work."
Mins 5-15 - Direct Instruction: 1) Define: "Reversible Reactions And Equilibrium is..." 2) Key principle: "Most important:..." 3) Draw diagram, label live. 4) Real example: "Like In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions. - a real example worked through in full..."
Mins 15-25 - Guided Practice: Ex1: Teacher models. Ex2: Student tries with guidance. Ex3: Student independent.
Mins 25-35 - Independent Practice: 3-5 questions. Immediate feedback.
Worked Example 1: Basic

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. What is asked? In
  2. Recall knowledge:
  3. Apply: Heating drives the forward reaction (decomposition — endothermic). Cooling drives the backward reaction (reformation — exothermic). Observation: white solid disappears on heating (produces two gases) and reappears on cooling.
  4. Check: Check the units named in the question and sense-check the size of your answer.
  5. Answer: State the complete final answer.

Tip: "Show working - method marks > answer marks."

Worked Example 2: Multi-step

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. Break down: Separate parts?
  2. Solve each: Heating drives the forward reaction (decomposition — endothermic). Cooling drives the backward reaction (reformation — exothermic). Observation: white solid disappears on heating (produces two gases) and reappears on cooling.
  3. Combine: The parts chain: each answer feeds the next step of the question.
  4. Final answer: Evidence cited from the lesson content.
Worked Example 3: Data/Application

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. Read data: Axes, units, scale
  2. Patterns: Trends, anomalies
  3. Explain: Why? Using reversible reactions and equilibrium
  4. Conclude: Evidence-based

Common Questions & Troubleshooting

Q: "Why does Reversible Reactions And Equilibrium work this way?"
A: Analogy: "In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.". Try re-draw or re-write the worked example from memory, then check it against the model answer.
Q: "Wrong answers on calculations."
A: Checklist: units? formula? calculator mode? sig figs?
Q: "Can't remember key terms."
A: Flashcards (term front, def+diagram back). Spaced repetition: day 1, 3, 7.
Q: "Exam wording confuses me."
A: Commands: Describe=what you see; Explain=reasons; Evaluate=pros/cons+judgement; Calculate=working+units.
Q: "Running out of time."
A: 1 mark/min. Skip hard, return. Attempt all - partial marks count.

Assessment & Model Answers

Mastery Checklist:
  • [ ] Define Reversible Reactions And Equilibrium in own words
  • [ ] Identify features in diagram
  • [ ] Explain process step-by-step
  • [ ] Apply to unfamiliar context
  • [ ] Score 80%+ on past paper question

Model Answer: Past Paper Question

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  • 1 mark: [Key terminology]
  • 1 mark: [Mechanism/process]
  • 1 mark: [Application/example]
  • 1 mark: [Evaluation - Higher]

Model response: "[Complete answer with expected detail/terminology]"

Why full marks: [What makes this strong]

Stretch & Challenge (Grade 8-9):
  • Synoptic links: Connect to C21-rate-of-reaction / the next lesson
  • Real-world: Research use in industry, medicine or research
  • Advanced calc: Try a more challenging variant
  • Critical: "Evaluate limitations of today's model"
  • Research: Recent discovery on reversible reactions and equilibrium, summarise 100 words

Plenary (5 mins)

Exam Question Speed Round

5 quick questions, 1 min each. Mark together.

Assessment Criteria

Lesson 4: Exam Practice: Reversible Reactions And Equilibrium

Duration: 50 minutes

Starter Activity (5 minutes)

Review Previous Lesson

Quick recap: write 3 key points from last lesson on reversible reactions and equilibrium. Use mini-whiteboard or paper.

Main Content (35 minutes)

Parent/Teacher Guide:
Before lesson: Read script below. Prepare materials. Pre-teach key vocab: Reversible Reactions And Equilibrium.
If stuck: See Troubleshooting below. Break into smaller steps.
Extension: See Stretch & Challenge section.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: Reversible Reactions And Equilibrium. Goal: by the end you can in a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions, using the method shown step by step. Connects to the previous lesson in this unit because you'll reuse its method throughout today's work."
Mins 5-15 - Direct Instruction: 1) Define: "Reversible Reactions And Equilibrium is..." 2) Key principle: "Most important:..." 3) Draw diagram, label live. 4) Real example: "Like In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions. - a real example worked through in full..."
Mins 15-25 - Guided Practice: Ex1: Teacher models. Ex2: Student tries with guidance. Ex3: Student independent.
Mins 25-35 - Independent Practice: 3-5 questions. Immediate feedback.
Worked Example 1: Basic

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. What is asked? In
  2. Recall knowledge:
  3. Apply: Heating drives the forward reaction (decomposition — endothermic). Cooling drives the backward reaction (reformation — exothermic). Observation: white solid disappears on heating (produces two gases) and reappears on cooling.
  4. Check: Check the units named in the question and sense-check the size of your answer.
  5. Answer: State the complete final answer.

Tip: "Show working - method marks > answer marks."

Worked Example 2: Multi-step

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. Break down: Separate parts?
  2. Solve each: Heating drives the forward reaction (decomposition — endothermic). Cooling drives the backward reaction (reformation — exothermic). Observation: white solid disappears on heating (produces two gases) and reappears on cooling.
  3. Combine: The parts chain: each answer feeds the next step of the question.
  4. Final answer: Evidence cited from the lesson content.
Worked Example 3: Data/Application

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  1. Read data: Axes, units, scale
  2. Patterns: Trends, anomalies
  3. Explain: Why? Using reversible reactions and equilibrium
  4. Conclude: Evidence-based

Common Questions & Troubleshooting

Q: "Why does Reversible Reactions And Equilibrium work this way?"
A: Analogy: "In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.". Try re-draw or re-write the worked example from memory, then check it against the model answer.
Q: "Wrong answers on calculations."
A: Checklist: units? formula? calculator mode? sig figs?
Q: "Can't remember key terms."
A: Flashcards (term front, def+diagram back). Spaced repetition: day 1, 3, 7.
Q: "Exam wording confuses me."
A: Commands: Describe=what you see; Explain=reasons; Evaluate=pros/cons+judgement; Calculate=working+units.
Q: "Running out of time."
A: 1 mark/min. Skip hard, return. Attempt all - partial marks count.

Assessment & Model Answers

Mastery Checklist:
  • [ ] Define Reversible Reactions And Equilibrium in own words
  • [ ] Identify features in diagram
  • [ ] Explain process step-by-step
  • [ ] Apply to unfamiliar context
  • [ ] Score 80%+ on past paper question

Model Answer: Past Paper Question

Q: In a reversible reaction, the products can react back together to form the reactants. This means the reaction can go in both directions.

  • 1 mark: [Key terminology]
  • 1 mark: [Mechanism/process]
  • 1 mark: [Application/example]
  • 1 mark: [Evaluation - Higher]

Model response: "[Complete answer with expected detail/terminology]"

Why full marks: [What makes this strong]

Stretch & Challenge (Grade 8-9):
  • Synoptic links: Connect to C21-rate-of-reaction / the next lesson
  • Real-world: Research use in industry, medicine or research
  • Advanced calc: Try a more challenging variant
  • Critical: "Evaluate limitations of today's model"
  • Research: Recent discovery on reversible reactions and equilibrium, summarise 100 words

Plenary (5 mins)

Exam Question Speed Round

5 quick questions, 1 min each. Mark together.

Assessment Criteria

📝 Mark Scheme Guidance

How examiners mark C22: Read the command word carefully — State = one word/phrase (1 mark), Describe = pattern or detail (2 marks), Explain = reason with "because" (2–3 marks), Compare = similarities AND differences, Evaluate = both sides + conclusion. Method marks are awarded for correct working even if the final answer is wrong. Always show your working — unexplained answers score zero for AO2.

Success on C22 questions: Underline the command word, count the marks (one mark per point expected), and answer in the format the command word demands.

Board Notes & Revision Links

This lesson is examined by: AQA 8462 | Edexcel 1CH0 | OCR J248 | CCEA units. Tier and paper details vary - always check your board's current specification.

Follow-up revision: C18-reversible-reactions-and-equilibrium on GCSE Revise (notes, flashcards and auto-graded target tests for this exact topic).

📐 Reference Diagram

x y y = x² Origin (0,0)

✏️ Draw-Along Instructions

Parent/teacher: Draw the key diagram for rate: start with the main structure, add labels with arrows, then annotate with the key facts from the lesson. Use a ruler for straight lines.

Display the reference diagram (or draw it live) while pupils copy. Check each label as it is added.

Homework & Consolidation

Recommended Resources

🎓 Smart Lesson (Guided)