Lesson 3 of 3 — Acids & Alkalis

Ions & Neutralisation

Edexcel IGCSE 4SS0 — Spec 2.31 & 2.32

H⁺From Acid

OH⁻From Alkali

→

H₂O⚡ Neutral ⚡

Today you build the
equation that wins marks
on every paper.Acids, alkalis, bases — finally settled.

🌍 Why this matters: Antacid tablets neutralise stomach acid. Lime is added to acidic soil so crops grow. Bee stings are acidic — treat with baking soda. Today you learn why all these work the same way.

Learning Objectives:

2.31 – Know that acids in aqueous solution are a source of H⁺ ions and alkalis are a source of OH⁻ ions.
2.32 – Know that bases can neutralise acids.

Navigation: Arrow Keys / Spacebar | 40 minutes

🖨️ Differentiated Pupil Packs

Each pack auto-prints the correct tier of arrival, starter, worksheet and exit ticket.

FAB 4 · Arrival Task

FAB 4 Arrival – Recall from Lesson 2 (pH Scale)

Instructions: Answer all four in your book. Q1–3 recall from Lesson 2 (pH scale & UI). Q4 leads into today.

1. pH Recall

What pH range is strongly acidic?

pH 0–3.

2. UI colour

What colour is universal indicator at pH 7?

Green.

3. pH Classify

A solution has pH 9. Is it acidic, neutral, or alkaline?

Alkaline (weakly alkaline, pH 8–10).

4. Lead-in 🔬

Stomach acid has pH 1. Bleach has pH 12. What do you think makes one of them acidic and the other alkaline?

They contain different particles (ions). Today you learn which ion makes something acidic vs alkaline.

1. Classify

A solution has pH 9. Classify it using the 5 phrases.

Weakly alkaline (pH 8–10).

2. UI limitations

State one limitation of using universal indicator.

It only gives an approximate pH — colours between values can be hard to distinguish.

3. Compare two

Solution X has pH 1. Solution Y has pH 6. Which is more acidic, and why?

X is more acidic. The lower the pH number, the more acidic the solution.

4. Lead-in 🔬

Stomach acid (pH 1) and bleach (pH 12) are both chemicals — but they behave very differently. What do you think is physically inside the solution that makes one acidic and one alkaline?

Different ions in the solution. Acids contain H⁺ ions; alkalis contain OH⁻ ions. That is today's lesson.

1. Range comparison

Solution A has pH 2. Solution B has pH 5. Both are acidic — explain the difference.

A is strongly acidic (pH 0–3); B is weakly acidic (pH 4–6). A has many more acidic particles in solution.

2. UI vs pH meter

Suggest a more accurate alternative to UI and explain why it is better.

A pH meter — gives a precise numerical reading rather than approximate colour matching.

3. Phenolphthalein recall

Why might phenolphthalein be preferred over UI in a titration?

It has a sharp, distinct colour change (colourless → pink) at the end-point — UI's colour gradient is harder to pinpoint.

4. Lead-in 🔬

HCl, H₂SO₄ and HNO₃ are all acids. NaOH, KOH and Ca(OH)₂ are all alkalis. Predict what they each release when dissolved in water that makes them behave the same way.

All acids release H⁺ ions. All alkalis release OH⁻ ions. This is what classifies them — that's today's lesson.

Starter – Record in Books

Starter: Key Definitions (5 mins)

Instructions: Copy these key definitions into your book. You will need them for today's lesson.

📝 Copy these definitions:

Acid: A substance that releases hydrogen ions (H⁺) when dissolved in water.

Alkali: A substance that releases hydroxide ions (OH⁻) when dissolved in water.

Base: Any substance that can neutralise an acid. All alkalis are bases, but not all bases are alkalis.

Neutralisation: The reaction between an acid and a base that produces water (and a salt).

Say this in the exam: "An alkali is a soluble base that dissolves in water to release OH⁻ ions." The word soluble is the difference — miss it, lose the mark.

Base vs Alkali

🌟 Extension: Copper oxide (CuO) neutralises acid but doesn't dissolve in water. Is it a base or an alkali? Why?

I Do

I Do: Acids, Alkalis & Ions (2.31)

🎯 The big idea: The ions in solution determine whether something is acidic or alkaline. Acids release H⁺. Alkalis release OH⁻. That's it.

🔴 Acids Release H⁺ Ions

When an acid dissolves in water, it releases hydrogen ions (H⁺).

HCl(aq) → H⁺(aq) + Cl⁻(aq)

More H⁺ ions = more acidic = lower pH.

🔵 Alkalis Release OH⁻ Ions

When an alkali dissolves in water, it releases hydroxide ions (OH⁻).

NaOH(aq) → Na⁺(aq) + OH⁻(aq)

More OH⁻ ions = more alkaline = higher pH.

💡 Memory trick: H⁺ = Hydrogen = from acids. OH⁻ = OH dear, that's an alkali!

What's In the Solution?

Alkalis release H⁺ ions — wrong way round!

Correct: Alkalis release OH⁻ ions. Acids release H⁺.

We Do

We Do: Ion Sort Challenge

As a class: Click an ion card, then click the correct category to sort it. Score: 0/6

🔴 H⁺

🔵 OH⁻

💧 H₂O

🧪 HCl

🧴 NaOH

🧂 NaCl

🔴 From ACIDS
Release H⁺ ions

🔵 From ALKALIS
Release OH⁻ ions

🟢 PRODUCTS
Made during neutralisation

I Do

I Do: Bases Neutralise Acids (2.32)

Key Idea: When a base reacts with an acid, the H⁺ and OH⁻ ions combine to form water. This is neutralisation.

⚗️ The Ionic Equation

H⁺(aq) + OH⁻(aq) → H₂O(l)

The hydrogen ion from the acid combines with the hydroxide ion from the base to produce water. This is true for every neutralisation — same equation every time.

📋 The Word Equation

Acid + Base → Salt + Water

Example: HCl + NaOH → NaCl + H₂O. The salt (NaCl) depends on which acid and base you use.

🌟 Insoluble bases: Copper oxide (CuO) is a base but NOT an alkali (it doesn't dissolve in water). It still neutralises acid: CuO + H₂SO₄ → CuSO₄ + H₂O.

Neutralisation – What Happens

🧪 Simulator: Add Base to Acid

pH:1

🔴 Strongly Acidic

🔬 Ion Animation: What the Ions Actually Do

Pick an acid, then press Next step. The ionic equation is the same every time — only the salt changes.

H⁺(aq) + OH⁻(aq) → H₂O(l)

Step 1 of 4 — Two solutions, four ions. Nothing has reacted yet.

🔍 Spot the Mistake

Spot the Mistake: Ions & Neutralisation

A student wrote the answer below. It contains THREE mistakes. Click each wrong word/phrase to identify it. Discuss with your partner first.

Acids dissolve in water and release hydrogen ions, which makes the pH low. Alkalis are different — they release hydrogen ions in water. Copper oxide (CuO) neutralises acids but doesn't dissolve in water — that means CuO is an alkali. When neutralisation happens, the acid and base react to form a salt and the pH ends up at 0.

Click a word or phrase you think is wrong.

We Do

We Do: Equation Builder & Base or Alkali?

As a class: Two activities. Build the ionic equation, then sort substances as base-only or alkali.

🧩 Build the Ionic Equation

Click the parts in the correct order to build the neutralisation equation:

🏷️ Base or Alkali?

Click a substance, then click "Base" or "Alkali":

NaOH

CuO

KOH

MgO

BASE only
Neutralises acid but insoluble

ALKALI
Soluble base (dissolves)

Independent Work – 8 mins

Independent Work

Answer independently. Use your scaffold sheet if needed. ⭐ = stretch question (one tier above). 🌍 = real-world synthesis.
❌ Never write: "alkalis release H+" or "CuO is an alkali". Use the right ion + the right classification.

Questions completed: 0/0

📗 Grades U–1 • Six question types • Q5 ⭐ stretch → Grade 2 • Q6 🌍 real-world synthesis

MCQ

1. Acids release which ion in water?

H⁺ starts with H for Hydrogen.

H⁺OH⁻Na⁺

Short answer

2. Complete: Acid + Base → ________ + ________.

One you'd put on chips. The other you drink.

Salt + Water.

Long answer [3]

3. Describe what happens when an acid is mixed with an alkali. Include in your answer: (a) which ions react, (b) what is produced, (c) what happens to the pH.

Three things: which ions / what gets made / pH end value.

The H⁺ ions from the acid react with OH⁻ ions from the alkali [1]. Water (H₂O) is produced [1]. The pH moves towards 7 (neutral) [1].

Diagram

4. Which beaker contains the acid?

Beaker A

Beaker B

Acid releases H⁺. Look at the ions in each.

Beaker A — it contains H⁺ ions, which are released by acids.

⭐ Challenge GCSE [3]

5. A student says "All bases are alkalis". Is the student correct? Explain your answer.

Think about CuO — does it dissolve? Does it neutralise acid?

No, the student is wrong [1]. All alkalis are bases (because they neutralise acid) [1], but not all bases are alkalis — some bases (like CuO) don't dissolve in water and so are NOT alkalis [1].

Synthesis [3]

6. Sam has heartburn — too much stomach acid. They take an antacid tablet (which contains a base).
(a) What type of reaction happens in Sam's stomach? [1]
(b) What is produced from this reaction? [1]
(c) What happens to the pH inside Sam's stomach? [1]

Acid + base = …? Products of every neutralisation are the same. pH moves towards which number?

(a) Neutralisation [1]. (b) Salt and water [1]. (c) The pH increases — moving towards 7 (neutral) [1].

📙 Grades 1–2 • Six question types • Q5 ⭐ stretch → Grade 3 • Q6 🌍 real-world synthesis

MCQ

1. NaOH dissolves in water and releases OH⁻. This means NaOH is:

Soluble + releases OH⁻ = which classification?

An acidAn alkaliA salt

Short answer

2. What is the difference between a base and an alkali?

One always works as both. The other can be insoluble.

A base is any substance that neutralises an acid. An alkali is a base that dissolves in water (releasing OH⁻).

Long answer [4]

3. Explain what happens at the ion level when HCl reacts with NaOH. Include the ions released by each, the ions that combine, and the products formed.

HCl → H⁺ + Cl⁻. NaOH → Na⁺ + OH⁻. Which ions combine?

HCl releases H⁺ and Cl⁻ ions [1]. NaOH releases Na⁺ and OH⁻ ions [1]. The H⁺ combines with OH⁻ to form water [1]. Na⁺ and Cl⁻ remain to form the salt sodium chloride (NaCl) [1].

Equation

4. Complete the word equation:

HCl + KOH → ________ + ________

Acid + base = salt + water. Metal from base + ending from acid.

KCl (potassium chloride) + H₂O (water).

⭐ Challenge GCSE [4]

5. A student adds NaOH (alkali) to HCl (acid) drop by drop while monitoring with universal indicator.
(a) State the type of reaction occurring. [1]
(b) What colour change(s) would the student see? [2]
(c) Write the ionic equation for the reaction. [1]

UI starts red (acid). Where does it end? What pH gives the colour change?

(a) Neutralisation [1]. (b) UI starts red (acid, pH 0–3); as alkali is added, it shifts through orange → yellow → green (pH 7) and eventually purple if excess is added [2]. (c) H⁺(aq) + OH⁻(aq) → H₂O(l) [1].

Synthesis [4]

6. A farmer's field is too acidic (pH 5) to grow good crops. The farmer adds lime (calcium hydroxide, Ca(OH)₂) to the soil.
(a) Is calcium hydroxide a base or an alkali? Explain. [2]
(b) Name the ion released by Ca(OH)₂ that does the neutralising. [1]
(c) What happens to the pH of the soil? [1]

Does Ca(OH)₂ dissolve in water? Yes — slightly. So it's both a base AND an alkali.

(a) It is both a base and an alkali — it neutralises acid (so it's a base) AND it dissolves in water releasing OH⁻ ions (so it's also an alkali) [2]. (b) OH⁻ (hydroxide) ions [1]. (c) The pH increases — moves up towards 7 (or above) — neutralising the acidic soil [1].

📘 Grades 3–4 • Six question types • Q5 ⭐ stretch → Grade 5 • Q6 🌍 real-world synthesis

MCQ

1. The ionic equation for neutralisation is:

Only the reacting ions appear — the spectator ions don't.

H⁺(aq) + OH⁻(aq) → H₂O(l)HCl + NaOH → NaCl + H₂OAcid + Base → Salt + Water

Short answer

2. Explain why CuO is classified as a base but not as an alkali.

Two things: does it neutralise acid? Does it dissolve?

CuO neutralises acids (so it is a base) but it does not dissolve in water, so it cannot release OH⁻ ions in aqueous solution — therefore it is not an alkali.

Long answer [4]

3. Predict the products of the following reactions. Write the word equation in each case:
(a) HCl + KOH → ?
(b) H₂SO₄ + Ca(OH)₂ → ?
(c) HNO₃ + NaOH → ?
(d) HCl + CuO → ?

Salts formed: HCl → chloride; H₂SO₄ → sulfate; HNO₃ → nitrate. Metal from the base.

(a) Potassium chloride + water [1]. (b) Calcium sulfate + water [1]. (c) Sodium nitrate + water [1]. (d) Copper chloride + water [1].

Diagram / Mechanism

4. Sketch (or describe) what happens to the H⁺ and OH⁻ ions during a neutralisation reaction. Use arrows to show the ions combining and label the product.

H⁺ + OH⁻ → ? Show the arrow showing them combining.

A diagram showing H⁺ ion and OH⁻ ion approaching each other, an arrow → between them, and the product H₂O (water). H⁺ + OH⁻ → H₂O. The ions combine to form a covalent bond, producing water — pH moves to 7.

⭐ Challenge GCSE [5]

5. Magnesium oxide (MgO) is added to dilute sulfuric acid (H₂SO₄). The MgO is in excess.
(a) Is MgO a base, an alkali, or both? Explain. [2]
(b) Write the balanced word equation. [1]
(c) Write the ionic equation for neutralisation. [1]
(d) State what would be observed. [1]

MgO is insoluble in water → base only. Sulfate salt = MgSO₄.

(a) Base only — it neutralises acid but does not dissolve in water (insoluble), so cannot release OH⁻ ions in solution [2]. (b) MgO + H₂SO₄ → MgSO₄ + H₂O [1]. (c) H⁺(aq) + OH⁻(aq) → H₂O(l) [1]. (d) The MgO solid would slowly disappear/dissolve as it reacts; the solution would warm up; some unreacted MgO solid would remain (excess) [1].

Synthesis [5]

6. An industrial chemist has spilled 100 litres of dilute sulfuric acid (H₂SO₄, pH 2) onto the lab floor. They have two options to neutralise it: (A) sodium hydroxide solution (NaOH); or (B) calcium oxide powder (CaO).
(a) Classify each option as base, alkali, or both. [2]
(b) Suggest one safety advantage and one disadvantage of using NaOH for this spill. [2]
(c) Write the ionic equation for the neutralisation that occurs in both cases. [1]

NaOH dissolves in water (alkali); CaO is a solid that doesn't dissolve much (base only).

(a) NaOH = both a base AND an alkali (soluble, releases OH⁻); CaO = base only (insoluble) [2]. (b) Advantage: NaOH (aq) reacts very quickly because it's already dissolved and OH⁻ is available. Disadvantage: NaOH is itself corrosive — too much would create another hazard (alkaline burn) — and adds liquid volume. Accept similar reasoning [2]. (c) H⁺(aq) + OH⁻(aq) → H₂O(l) — same equation in both cases (CaO reacts with water first to make Ca(OH)₂, releasing OH⁻) [1].

Exit Ticket – Lessons 1–3 Cumulative

Exit Ticket – Acids & Alkalis Series Recap

No notes. 6 recall questions covering all three lessons. Answer from memory in 3 minutes.

1) What colour does litmus turn in an acidic solution?

Red.

2) Name one advantage of universal indicator over litmus.

UI shows a range of colours — gives an approximate pH, not just acid or alkali.

3) What pH range is "weakly alkaline"?

pH 8–10.

4) What colour is universal indicator at pH 7?

Green.

5) What ion do acids release in water?

H⁺ (hydrogen ions).

6) What do you get when an acid reacts with a base?

Salt and water.

Knowledge Organiser – Lesson 3: Ions & Neutralisation

Term	Detail
Acid	A substance that releases H⁺ (hydrogen) ions in aqueous solution. Examples: HCl, H₂SO₄, HNO₃.
Alkali	A soluble base that releases OH⁻ (hydroxide) ions in aqueous solution. Examples: NaOH, KOH, Ca(OH)₂.
Base	Any substance that can neutralise an acid. All alkalis are bases. Not all bases are alkalis (some are insoluble, e.g. CuO, MgO).
Neutralisation	Acid + Base → Salt + Water. The H⁺ and OH⁻ ions combine to form water.
Ionic Equation	H⁺(aq) + OH⁻(aq) → H₂O(l) — same for ALL neutralisation reactions.
H⁺ ions	Hydrogen ions — released by acids. More H⁺ = more acidic = lower pH.
OH⁻ ions	Hydroxide ions — released by alkalis. More OH⁻ = more alkaline = higher pH.
Salt naming	HCl → chloride; H₂SO₄ → sulfate; HNO₃ → nitrate. The metal comes from the base.

Arrival Task – Foundation (Recall from Lesson 2)

1. What pH range is strongly acidic?

2. What colour is universal indicator at pH 7?

3. A solution has pH 9. Is it acidic, neutral, or alkaline?

4. Lead-in: Stomach acid has pH 1 and bleach has pH 12. What makes one acidic and the other alkaline?

Arrival Task – Middle (Recall from Lesson 2)

1. A solution has pH 9. Classify using the 5 phrases.

2. State one limitation of universal indicator.

3. Solution X has pH 1, Y has pH 6. Which is more acidic? Why?

4. Lead-in: What do you think is physically inside an acid that makes it acidic?

Arrival Task – Higher (Recall from Lesson 2)

1. Solution A is pH 2, B is pH 5. Both acidic — explain the difference.

2. Suggest a more accurate alternative to UI and explain why.

3. Why might phenolphthalein be preferred over UI in a titration?

4. Lead-in: All acids behave the same way. Predict what they release in water.

Starter: Key Definitions

Copy these into your book. Learn them — they appear on every paper.

Term	Definition
Acid	A substance that releases H⁺ (hydrogen) ions in water.
Alkali	A substance that releases OH⁻ (hydroxide) ions in water.
Base	Any substance that can neutralise an acid. Alkalis are soluble bases.
Neutralisation	Acid + Base → Salt + Water.

Diagram task: Sketch the Bases/Alkalis Venn — a big "Bases" circle with a smaller "Alkalis" circle inside. Add CuO and MgO outside the alkalis circle (insoluble bases) and NaOH/KOH inside (soluble bases = alkalis).

We Do – Ion Sort & Equation Builder

Part 1: Write each item in the correct column: H⁺, OH⁻, H₂O, HCl, NaOH, NaCl

From ACIDS (release H⁺)	From ALKALIS (release OH⁻)	PRODUCTS of Neutralisation

Part 2: Write the ionic equation for neutralisation by filling in the blanks:

_______(aq) + _______(aq) → _______(l)

Part 3: Write each substance in the correct column: NaOH, CuO, KOH, MgO

BASE only (insoluble)	ALKALI (soluble base)

Part 4 — Spot the Mistake: The student wrote: "Acids dissolve in water and release hydrogen ions, which makes the pH low. Alkalis are different — they release hydrogen ions in water. Copper oxide (CuO) neutralises acids but doesn't dissolve in water — that means CuO is an alkali. When neutralisation happens, the acid and base react to form a salt and the pH ends up at 0."

Underline the three mistakes and write the corrections below:

Scaffolding Sheet

Key Ions

Acids → release H⁺ ions (hydrogen). More H⁺ = lower pH = more acidic.

Alkalis → release OH⁻ ions (hydroxide). More OH⁻ = higher pH = more alkaline.

Neutralisation

Word equation: Acid + Base → Salt + Water

Ionic equation: H⁺(aq) + OH⁻(aq) → H₂O(l)

Example: HCl + NaOH → NaCl + H₂O

Base vs Alkali

Base = any substance that neutralises an acid (e.g. CuO, MgO, NaOH).

Alkali = a base that dissolves in water (e.g. NaOH, KOH).

All alkalis are bases. Not all bases are alkalis.

📝 Word Bank (Foundation)

Use these words: acid, alkali, base, H⁺, OH⁻, neutralisation, salt, water, pH 7, dissolves, insoluble, ions, hydrogen, hydroxide

✍️ Sentence Starters

• Acids release ___ ions

• Alkalis release ___ ions

• A base is a substance that...

• Acid + Base → ___ + ___

• The difference between a base and an alkali is...

Exam Tips (Higher)

• The ionic equation H⁺ + OH⁻ → H₂O is the same for all neutralisations.

• An insoluble base like CuO still neutralises acid but does not release OH⁻ ions into solution directly.

• The salt depends on the acid and the metal in the base: HCl → chloride, H₂SO₄ → sulfate, HNO₃ → nitrate.

• "Soluble base" = alkali. Use this exact phrase in your answers for full marks.

Independent Work – Foundation (Grades U–1)

Multiple Choice & Short Answer

1. What type of ion do acids release in water?

[ ] OH⁻ [ ] H⁺ [ ] Na⁺

2. Complete: Acid + Base → ________ + ________.

Long Answer

3. Describe what happens when an acid is mixed with an alkali. Include: (a) which ions react, (b) what is produced, (c) what happens to the pH.

4. Beaker A has H⁺ ions. Beaker B has OH⁻ ions. Which is the acid?

Exam-Style Questions

5. ⭐ [3 marks] A student says "All bases are alkalis". Is the student correct? Explain.

6. 🌍 [3 marks] Sam has heartburn — too much stomach acid. They take an antacid (which is a base). (a) What type of reaction happens? [1] (b) What is produced? [1] (c) What happens to the pH? [1]

Independent Work – Middle (Grades 1–2)

Multiple Choice & Short Answer

1. NaOH dissolves in water and releases OH⁻. NaOH is:

[ ] An acid [ ] An alkali [ ] A salt

2. State the difference between a base and an alkali.

Long Answer

3. Explain what happens at the ion level when HCl reacts with NaOH. Include the ions released by each, the ions that combine, and the products.

4. Complete: HCl + KOH → ________ + ________.

Exam-Style Questions

5. ⭐ [4 marks] A student adds NaOH to HCl drop by drop while monitoring with universal indicator.

(a) State the type of reaction. [1]

(b) Describe the colour changes seen. [2]

6. 🌍 [4 marks] A farmer's field is too acidic (pH 5). They add lime (Ca(OH)₂).

(a) Is calcium hydroxide a base or alkali? Explain. [2]

(b) Name the ion that does the neutralising. [1]

Independent Work – Higher (Grades 3–4)

Multiple Choice & Short Answer

1. Tick the ionic equation for neutralisation:

[ ] H⁺(aq) + OH⁻(aq) → H₂O(l) [ ] HCl + NaOH → NaCl + H₂O

2. Explain why CuO is a base but not an alkali.

Long Answer

3. Predict the products of these reactions. Write the word equation:

Reaction	Word Equation
HCl + KOH →
H₂SO₄ + Ca(OH)₂ →
HNO₃ + NaOH →
HCl + CuO →

4. Sketch what happens to H⁺ and OH⁻ ions during neutralisation. Use arrows and label the product.

Exam-Style Questions

5. ⭐ [5 marks] Excess MgO is added to dilute H₂SO₄.

(a) Is MgO a base, alkali, or both? Explain. [2]

(b) Write the balanced word equation. [1]

(d) State what would be observed. [1]

6. 🌍 [5 marks] A chemist has spilled 100 L of dilute H₂SO₄ (pH 2). Two options: (A) NaOH solution; (B) CaO powder.

(a) Classify each option as base, alkali, or both. [2]

(b) Suggest one safety advantage and one disadvantage of using NaOH. [2]

Exit Ticket – Foundation (U–1) (Lessons 1–3 Recap)

L1 – Indicators

1) What colour does litmus turn in acid?

L1 – Universal Indicator

2) Name one advantage of UI over litmus.

L2 – pH Scale

3) What pH range is "weakly alkaline"?

L2 – pH Scale

4) What colour is UI at pH 7?

L3 – Ions

5) What ion do acids release in water?

L3 – Neutralisation

6) What do you get when acid reacts with a base?

Exit Ticket – Middle (1–2) (Lessons 1–3 Recap)

L1 – Indicators

1) What colour does phenolphthalein turn in alkali?

L1 – Indicators

2) What colour does methyl orange turn in acid?

L2 – pH Scale

3) A solution has pH 12. Classify it.

L2 – Universal Indicator

4) State one limitation of universal indicator.

L3 – Base vs Alkali

5) What is the difference between a base and an alkali?

L3 – Neutralisation

6) Write the word equation for neutralisation.

Exit Ticket – Higher (3–4) (Lessons 1–3 Recap)

L1 – Indicators

1) Explain why phenolphthalein is preferred over UI in a titration.

L1 – Indicators

2) State methyl orange colours in acid and alkali.

L2 – pH Scale

3) pH 2 vs pH 5: explain the difference.

L2 – Measuring pH

4) Suggest a more accurate alternative to UI. Explain why.

L3 – Neutralisation

5) Write the ionic equation for neutralisation.

L3 – Bases

6) CuO neutralises H₂SO₄. Base or alkali? Explain.

Lesson Complete!

TA Focus

Cold Call

Ions & Neutralisation

🖨️ Differentiated Pupil Packs

FAB 4 Arrival – Recall from Lesson 2 (pH Scale)

1. pH Recall

2. UI colour

3. pH Classify

4. Lead-in 🔬

1. Classify

2. UI limitations

3. Compare two

4. Lead-in 🔬

1. Range comparison

2. UI vs pH meter

3. Phenolphthalein recall

4. Lead-in 🔬

Starter: Key Definitions (5 mins)

📝 Copy these definitions:

Base vs Alkali

I Do: Acids, Alkalis & Ions (2.31)

🔴 Acids Release H⁺ Ions

🔵 Alkalis Release OH⁻ Ions

What's In the Solution?

We Do: Ion Sort Challenge

I Do: Bases Neutralise Acids (2.32)

⚗️ The Ionic Equation

📋 The Word Equation

Neutralisation – What Happens

🧪 Simulator: Add Base to Acid

🔬 Ion Animation: What the Ions Actually Do

Spot the Mistake: Ions & Neutralisation

We Do: Equation Builder & Base or Alkali?

🧩 Build the Ionic Equation

🏷️ Base or Alkali?

Independent Work

Exit Ticket – Acids & Alkalis Series Recap

Knowledge Organiser – Lesson 3: Ions & Neutralisation

Arrival Task – Foundation (Recall from Lesson 2)

Arrival Task – Middle (Recall from Lesson 2)

Arrival Task – Higher (Recall from Lesson 2)

Starter: Key Definitions

We Do – Ion Sort & Equation Builder

Scaffolding Sheet

Key Ions

Neutralisation

Base vs Alkali

📝 Word Bank (Foundation)

✍️ Sentence Starters

Exam Tips (Higher)

Independent Work – Foundation (Grades U–1)

Multiple Choice & Short Answer

Long Answer

Exam-Style Questions

Independent Work – Middle (Grades 1–2)

Multiple Choice & Short Answer

Long Answer

Exam-Style Questions

Independent Work – Higher (Grades 3–4)

Multiple Choice & Short Answer

Long Answer

Exam-Style Questions

Exit Ticket – Foundation (U–1) (Lessons 1–3 Recap)

Exit Ticket – Middle (1–2) (Lessons 1–3 Recap)

Exit Ticket – Higher (3–4) (Lessons 1–3 Recap)

We Do – Class Evidence