Lesson 4b — Chemical Analysis

Gas Tests II: NH₃ & Cl₂

Spec: 2.44

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🌍 Did you know? The chlorine that bleaches litmus white is the same chemistry that keeps swimming pools safe to swim in — it destroys germs the way it destroys the dye.

Learning Objective:

2.44 – Describe tests for ammonia and chlorine, and recall all five gas tests.

🏆 Success Criteria — I will…

…name the litmus tests for NH₃ and Cl₂, and recall all five tests.
…state what I would observe (the positive result).
…write an observation → conclusion sentence.

Navigation: Arrow Keys / Spacebar | 40 minutes | TA Focus & Cold Call top-left

🖨️ Pupil Packs

Arrival Task

Arrival Task – Recall from Last Lesson

Welcome back! Last lesson: three gas tests. In your books, answer from memory — use the 💡 hints and word bank if stuck. Pick your level below.
🧠 Today's new pair: BLUE = ammonia, WHITE (bleached) = chlorine.

1. Hydrogen

Tap the test + result for H₂:

Burning splint → squeaky popGlowing splint → relightsLimewater → milky

"Burns with a Bang."

Burning splint → squeaky pop.

2. Oxygen

Tap the test + result for O₂:

Burning splint → squeaky popGlowing splint → relightsLimewater → milky

"Glows and Goes."

Glowing splint → relights.

3. Carbon dioxide

Fill the gap: CO₂ turns limewater ______.

LIMEwater goes MILKY.

Milky / cloudy.

4. Today's Lead-in 🔬

Your Starter predictions last lesson — which TWO gases are still unchecked?

The two tested with damp litmus paper.

Ammonia (NH₃) and chlorine (Cl₂) — today's gases.

1. The splint test

A glowing splint is lowered into a gas and it relights. The gas is:

HydrogenOxygenCarbon dioxide

Which gas supports burning, so it relights an ember?

Oxygen — it supports combustion, so the glowing ember bursts back into flame.

2. Name the gas

A burning splint at the mouth of a tube gives a squeaky pop. Name the gas.

"Burns with a Bang."

Hydrogen (H₂).

3. Spot the correct one

Which statement is correct?

H₂ uses a BURNING splint; O₂ uses a GLOWING splintH₂ uses a GLOWING splint; O₂ uses a BURNING splintBoth use a glowing splint

Hydrogen needs a flame to ignite; oxygen re-lights an ember.

H₂ = BURNING splint (it ignites → pop). O₂ = GLOWING splint (it relights the ember).

4. Today's Lead-in 🔬

Both of today's gases (NH₃ and Cl₂) are tested with the same piece of equipment. What is it?

It must be DAMP so the gas can dissolve into it…

Damp litmus paper — the difference is the result (blue vs bleached white).

1. From memory

Complete the three tests (use the word bank):

H₂ → ____ splint → ____
O₂ → ____ splint → ____
CO₂ → bubble through ____ → turns ____

Two are splint tests; one uses a liquid.

H₂ → burning splint → squeaky pop. O₂ → glowing splint → relights. CO₂ → limewater → turns milky.

2. Pick the right word

Finish the sentence:

"We use a ______ splint for hydrogen but a ______ splint for oxygen."

Choose from: burning / glowing

…a burning splint for hydrogen but a glowing splint for oxygen.

3. Why damp?

Why must litmus paper be damp when testing NH₃ and Cl₂?

The gas dissolves in the moisture and reaches the dyeTo make the paper strongerTo cool the gas down

A gas can only change an indicator once it is in solution.

The gas dissolves in the moisture, forming a solution that reacts with the indicator dye.

4. Today's Lead-in 🔬 — predict

Finish the prediction:

"Ammonia is the only ______ gas, so it turns litmus ______. Chlorine is a ______, so it ______ the litmus ______."

Choose from: alkaline · bleach · blue · white · bleaches

Ammonia is the only alkaline gas, so it turns litmus blue. Chlorine is a bleach, so it bleaches the litmus white.

🧰 Word bank: burning · glowing · splint · pop · relights · limewater · milky · damp litmus · alkaline · bleach · blue · bleached white · NH₃ · Cl₂

Starter – Final Two Predictions

Starter: Two Predictions Left 🔮 (3 mins)

Three confirmed last lesson: H₂ burning→pop ✔ · O₂ glowing→relights ✔ · CO₂ limewater→milky ✔.
Two still open. Lock in (or change!) your prediction for ammonia and chlorine — we test them today.

NH₃ Ammonia🔥 Burning splint✨ Glowing splint📄 Litmus turns BLUE📄 Litmus BLEACHED white

Cl₂ Chlorine🔥 Burning splint✨ Glowing splint📄 Litmus turns BLUE📄 Litmus BLEACHED white

Predictions made: 0/2

🌟 Extension: WHY did you pick that? Clue: ammonia is the only common alkaline gas…

Brain Dump: 60 seconds — write or say EVERYTHING you remember about last lesson's three gas tests. Mini-whiteboards out.

✔ H₂ → burning splint → squeaky pop · ✔ O₂ → glowing splint → relights · ✔ CO₂ → bubble through limewater → milky. Bonus tick: did you write BURNING/GLOWING, not just "splint"?

🌟 Stretch: add the equation for the pop: 2H₂ + O₂ → 2H₂O.

Which is the odd one out — and WHY? Any answer with a reason scores. Talk first, then reveal.

NH₃ AmmoniaCl₂ ChlorineCO₂ Carbon dioxideO₂ Oxygen

All defensible: NH₃ — the only ALKALINE gas / only one turning litmus BLUE · Cl₂ — the only BLEACHER · CO₂ — the only one tested with a liquid · O₂ — the only splint test here. The reason is the science.

🌟 Stretch: make a four-item odd-one-out using ALL five gases minus one.

I Do 🦉 OWL · OBSERVE

Observe: The Litmus Tests For Real 👀

Run the litmus lab, then watch the REAL tests. For each: say the TEST, predict the OBSERVATION, then run it. Were your Starter predictions right?

🧪 THE LITMUS LAB — tap a station to test the gas

💧 Damp paper · RED litmus for NH₃, BLUE litmus for Cl₂ · results stay until reset

GCSE Science Chemistry (9-1) · Tests for Gases. If blocked on the school network, use the buttons.

▶ All 5 (incl. NH₃ & Cl₂) ↗ ▶ Carbon dioxide (recap) ↗

👀 Say it as you watch: I see ___, so the gas is ___.

I Do

I Do: Testing for NH₃ and Cl₂

Continue filling in your table with these last two gas tests. 🔮 Prediction check: who called these in the Starter? BLUE = ammonia · WHITE = chlorine.

NH₃

Ammonia

Test: Hold damp red litmus paper near the gas.

Result: The paper turns blue.

Ammonia is the only common alkaline gas. It dissolves in the moisture on the paper to form an alkaline solution, which turns litmus blue.

Cl₂

Chlorine

Test: Hold damp litmus paper (blue or red) near the gas.

Result: The paper is bleached white (decolourised).

Chlorine is a powerful bleaching agent. It destroys the dye in the paper. ⚠️ Chlorine is toxic — scientists test it in a fume cupboard.

💡 Don't confuse them!
• NH₃: litmus turns blue (alkaline gas)
• Cl₂: litmus goes white (bleached, destroyed)
Both use damp litmus paper, but the result is very different!

🧠 Memory hook: "BLUE for ammonia (it's Alkaline)" · "WHITE-out for chlorine (it bleaches)". Both use damp litmus — the only difference is the result.

Don't write: "the litmus changes colour" or just "litmus paper"

Write: damp red litmus turns BLUE (NH₃) · damp litmus is BLEACHED WHITE (Cl₂)

Always say the colour change (blue) or bleached white, and always say the litmus is damp — dry paper scores nothing.

Ammonia vs Chlorine – Litmus Paper

🌟 Higher: Chlorine initially turns damp blue litmus red (because Cl₂ dissolves in water to form HCl, which is acidic), but then immediately bleaches it white. You might see a brief red flash before white.

We Do

We Do: Build the Answer 🧱🔬

🦉 OWL · LINK (observation → conclusion)

As a class: build the full exam answer for today's two gases — ammonia and chlorine. Drag each tile into Test → Observation → Conclusion. 0/6 built

✍️ Say it / write it: I saw ___, so the gas is ___.

Drag each tile into the right slot — or tap a tile, then tap its slot. Build Test → Observation → Conclusion for each gas.

NH₃ → damp RED litmus → turns BLUE → ammonia (the alkaline gas) · Cl₂ → damp litmus → BLEACHED WHITE → chlorine (the bleaching agent)

Damp RED litmus paper

Turns BLUE

Ammonia

Damp litmus paper

Bleached WHITE

Chlorine

🟢 Gas A — turns damp litmus BLUE

① TEST — what do you hold near the gas?

② OBSERVATION — what do you see?

③ CONCLUSION — so the gas is…

🟡 Gas B — litmus is bleached WHITE

① TEST — what do you hold near the gas?

② OBSERVATION — what do you see?

③ CONCLUSION — so the gas is…

Statement 1/6

👍 Thumbs-up / stand = TRUE · 👎 thumbs-down / stay sat = FALSE — everyone votes!

Tap the steps in the right order to build the exam method.

Independent Work – 8 mins

Independent Work

Answer independently. ❌ Never write just "splint" — always say BURNING splint or GLOWING splint.

Questions completed: 0/0

📗 Grades U–1 • Grade 2 challenge marked with ⭐

MCQ

1. Damp RED litmus turns BLUE. The gas is:

The only common ALKALINE gas.

NH₃Cl₂CO₂

MCQ

2. Chlorine turns damp litmus paper:

Chlorine = bleach.

Bleached whiteBlueMilky

Short

3. Which TWO gases are tested with damp litmus paper?

Today's two gases!

Ammonia (NH₃) and chlorine (Cl₂).

Short

4. 🔁 Mixed: what does CO₂ do to limewater?

LIMEwater goes MILKY.

Turns it milky/cloudy.

⭐ Exam [3 marks]

5. A student holds damp litmus in a gas. It goes white. (a) Name the gas [1]. (b) State the test [1]. (c) What happened to the litmus? [1]

Chlorine = bleach. What happens when you bleach something?

(a) The gas is ______. (b) The test: hold damp ______ litmus paper in the gas. (c) The litmus is ______ ______.

(a) Chlorine. (b) Hold damp litmus paper near the gas. (c) It was bleached/decolourised.

🌟 Finished? Flip to Middle and try Q2 — you already know blue vs white.

📙 Grades 2–3 • Grade 3 challenge marked with ⭐

MCQ

1. Why must the litmus paper be DAMP?

The gas has to get INTO the paper somehow.

So the gas can dissolve in the moisture and reach the dyeTo make the paper strongerTo keep the gas cool

Short

2. How can you tell apart ammonia and chlorine using damp litmus paper?

One changes the colour TO something; one DESTROYS the colour.

Ammonia turns damp red litmus blue (alkaline gas). Chlorine bleaches damp litmus white.

Short

3. 🔁 Mixed: a glowing splint relights. Name the gas and explain why.

Which gas supports combustion?

Oxygen — it supports combustion, so the glowing ember bursts back into flame.

⭐ Exam [4 marks]

4. A cleaning product releases a gas that bleaches damp litmus paper white. (a) Name the gas [1]. (b) Describe the test and the result [2]. (c) State ONE safety precaution when testing this gas [1].

Toxic gas — where would a scientist test it?

(a) The gas is ______. (b) Hold damp ______ litmus in the gas — it is ______ ______. (c) Safety: test in a ______ ______ because the gas is ______.

(a) Chlorine. (b) Hold damp litmus paper in the gas — it is bleached white. (c) Use a fume cupboard / well-ventilated area (chlorine is toxic).

🌟 Finished? Try the Higher MCQ (Q1) — the red-then-white story is one step beyond what you just wrote.

📘 Grades 3–5 • Grade 5 challenge marked with ⭐

MCQ

1. Chlorine turns damp blue litmus red then white because:

Cl₂ dissolves in the damp paper to form an acid (red) — then it bleaches (white).

Cl₂ + water → HCl (acidic, red) then bleachesChlorine is alkalineThe paper dries out in the gas

Short

2. Explain why ammonia turns damp red litmus blue. Name the solution formed.

NH₃ + water → an alkaline solution (think OH⁻).

Ammonia dissolves in the moisture forming ammonium hydroxide (an alkaline solution releasing OH⁻ ions) — alkalis turn red litmus blue.

Short

3. Chlorine reacts with water: Cl₂ + H₂O → HCl + HClO. Use this equation to explain BOTH stages of the litmus result.

One product is an acid. The other is the bleach. Match each to a stage.

HCl is acidic → the damp blue litmus turns RED first. HClO is the bleaching agent → it destroys the dye, so the paper turns WHITE.

⭐ Exam [6 marks]

4. A student has two unlabelled gas jars: one contains ammonia, one contains chlorine. Describe a plan to identify both gases. For each: state the test, the expected observation, and the conclusion. Include ONE safety point.

Same test for both — different results. Blue vs white.

Hold damp (red) litmus paper at the mouth of each jar. Jar that turns litmus BLUE → ammonia (alkaline gas). Jar where litmus is BLEACHED WHITE → chlorine (bleaching agent). Safety: chlorine is toxic — use a fume cupboard / do not inhale.

🎯 Examiner wants: the two-jars 6-marker = each jar gets Test → Observation → Conclusion, plus ONE safety point. Same test, different results — say so explicitly.

🌟 Finished? Write a mark scheme for the 6-marker: where exactly do the six marks sit? Compare with a partner.

Exit Ticket – 3 mins

Exit Ticket

No notes. From memory only. Your tier question = one observation + one conclusion. Then everyone answers the safety/method check below.

✅ Method check (everyone): Name one safety precaution when testing gases, OR explain why litmus paper must be damp.

1) What colour does damp red litmus turn in ammonia?

Blue.

2) What does chlorine do to damp litmus paper?

Bleaches it white.

3) Both gases are tested with the same equipment — what is it?

Damp litmus paper.

Name: ________________________ Class: __________ Date: ____________

🎯 Learning Objective (2.44): Describe tests for ammonia and chlorine, and recall all five gas tests.

🏆 Success Criteria — tick at the END of the lesson:

☐ I can name the litmus tests for NH₃ and Cl₂.

☐ I can recall all five gas tests from memory.

☐ I can write an observation → conclusion sentence.

Knowledge Organiser – Lesson 4b: Gas Tests II (NH₃ & Cl₂)

Gas	Formula	Test	Positive Result
Hydrogen	H₂	Hold a burning splint near the gas	Squeaky pop
Oxygen	O₂	Place a glowing splint in the gas	Splint relights
Carbon dioxide	CO₂	Bubble through limewater	Turns milky / cloudy
Ammonia	NH₃	Hold damp red litmus paper near gas	Turns blue (alkaline gas)
Chlorine	Cl₂	Hold damp litmus paper near gas	Bleached white (decolourised)

Key distinctions: Burning splint (flame visible) = H₂ test. Glowing splint (ember only) = O₂ test. Damp litmus must be used for NH₃ and Cl₂ so the gas can dissolve in moisture.

🧠 Self-quiz routine (everyone): COVER the table → WRITE all five tests from memory → CHECK → fix any gaps. Do it twice — the second go is where it sticks.

⚠️ Common mark-losers: writing just "splint" (say BURNING or GLOWING) · dry litmus (it must be DAMP) · swapping BLUE (ammonia) and WHITE (chlorine) · forgetting the safety point on chlorine (toxic → fume cupboard).

🎵 Memory hooks: "BLUE for ammonia" · "WHITE-out for chlorine" · and from last lesson: "Burns with a Bang" = H₂ · "Glows and Goes" = O₂ · "LIMEwater MILKY" = CO₂.

Arrival Task — Recall from Last Lesson

📌 Use this to help you:

• H₂ → BURNING splint → squeaky pop · O₂ → GLOWING splint → relights · CO₂ → bubble through limewater → turns milky

• NH₃ → damp RED litmus → turns BLUE (alkaline gas) · Cl₂ → damp litmus → BLEACHED WHITE (bleaching agent)

Foundation

1. Hydrogen test — circle: Burning splint→pop / Glowing splint→relights / Limewater→milky

2. Oxygen test — circle: Burning splint→pop / Glowing splint→relights / Limewater→milky

3. Fill the gap: CO₂ turns limewater ______.

4. Lead-in: Which TWO gases from your predictions are still unchecked? ______ and ______

Middle

1. A glowing splint is lowered in and relights. Name the gas. ______

2. A burning splint gives a squeaky pop. Name the gas. ______

3. Circle the correct one: H₂ = BURNING / GLOWING splint · O₂ = BURNING / GLOWING splint

4. Lead-in: Both NH₃ and Cl₂ use the same equipment — what is it? ______

Higher

1. Complete from memory:
H₂ → ______ splint → ______ · O₂ → ______ splint → ______ · CO₂ → bubble through ______ → turns ______

2. Finish (choose burning / glowing): "We use a ______ splint for hydrogen but a ______ splint for oxygen."

3. Explain why litmus must be DAMP for the NH₃ and Cl₂ tests.

4. Lead-in — predict. Choose from: alkaline · bleach · blue · white · bleaches.
"Ammonia is the only ______ gas, so it turns litmus ______. Chlorine is a ______, so it ______ the litmus ______."

🧰 Word bank: burning · glowing · splint · pop · relights · limewater · milky · damp litmus · alkaline · bleach · blue · bleached white · NH₃ · Cl₂

Gas Test Table — fill in during the lesson

Stick this in your book. Fill in each row as we learn the test (no copying needed).

Gas	Formula	Test	Positive Result
Hydrogen	H₂	Burning splint	Squeaky pop
Oxygen	O₂	Glowing splint	Relights
Carbon dioxide	CO₂	Bubble through limewater	Turns milky
Ammonia	NH₃
Chlorine	Cl₂

🔮 My final-two predictions I got right: ______ / 2

We Do: Build the Answer

Part 1: Complete the answer for each of today's gases — Test → Observation → Conclusion.

Gas	Test (what you hold near it)	Observation (what you see)	Conclusion (so the gas is…)
Turns litmus BLUE
Litmus bleached WHITE

Part 2: Write the full observation → conclusion sentence for each gas.

Ammonia: "I held damp ______ litmus near the gas. It ______. So the gas is ______."

Chlorine: "I held damp litmus near the gas. It was ______ ______. So the gas is ______."

Remember: the litmus must be damp, and chlorine is toxic → test it in a fume cupboard.

Scaffolding Sheet

All Five Gas Tests

Gas	Test	Result	Memory Aid
H₂	Burning splint	Squeaky pop	H₂ goes "pop!" like a tiny explosion
O₂	Glowing splint	Relights	O₂ supports burning – it lights things up
CO₂	Bubble through limewater	Turns milky	LIMEwater goes MILKY
NH₃	Damp red litmus	Turns blue	NH₃ is alkaline → litmus goes Blue
Cl₂	Damp litmus	Bleached white	Chlorine = cleaning = bleach!

Common Mistakes

• Don't confuse BURNING splint (H₂) with GLOWING splint (O₂).

• Litmus paper must be DAMP for NH₃ and Cl₂ tests.

• NH₃ turns litmus BLUE. Cl₂ turns litmus WHITE. Very different!

📝 Word Bank (Foundation)

Use these words: hydrogen, oxygen, carbon dioxide, ammonia, chlorine, burning splint, glowing splint, limewater, damp litmus, squeaky pop, relights, milky, blue, bleached white

✍️ Sentence Starters

• To test for ___, you use a...

• The positive result is...

• A burning splint is different from a glowing splint because...

• The gas is ___ because the test showed...

⭐ Exam frame: (a) The gas is ______. (b) The test: hold damp ______ litmus paper in the gas. (c) The litmus ______.

📙 Explain-It Toolkit (Middle)

Key words you MUST use: damp · dissolves · alkaline · blue · bleached white · fume cupboard · toxic

Explain stems: "The gas is ___ because…" · "The litmus must be damp so that…" · "You can tell them apart because one ___ and the other ___."

Self-check: every answer = TEST + RESULT + GAS NAME. Missing one = missing marks.

Chemistry Behind the Tests (Higher)

• H₂: 2H₂ + O₂ → 2H₂O (explosive combustion → pop)

• O₂: supports combustion → relights glowing material

• CO₂ + Ca(OH)₂ → CaCO₃ + H₂O (CaCO₃ is insoluble → milky)

• NH₃ dissolves in moisture → NH₄OH (alkaline) → turns litmus blue

• Cl₂ dissolves in moisture → HCl + HClO (bleaching agent → destroys dye)

🎯 Command words: DESCRIBE = say what happens · EXPLAIN = say WHY (use "because") · COMPARE = similarities AND differences · PLAN/METHOD = numbered steps.

6-mark frame (two jars): Jar 1 — TEST → OBSERVATION → CONCLUSION. Jar 2 — same three. + ONE safety point = six marks banked.

Independent Work – Foundation (Grades U–1)

Multiple Choice & Short Answer

1. Damp RED litmus turns BLUE. The gas is:

[ ] NH₃ [ ] Cl₂ [ ] CO₂

2. Chlorine turns damp litmus paper:

[ ] Bleached white [ ] Blue [ ] Milky

3. Which TWO gases use damp litmus paper?

______________ and ______________

4. 🔁 Mixed: what does CO₂ do to limewater?

Long Answer

5. Complete the table:

Gas	Test	Positive Result
Ammonia
Chlorine
🔁 Hydrogen

6. A student holds damp litmus paper in a gas and it is bleached white. Name the gas.

Exam-Style Questions

7. [3 marks] A student holds damp litmus paper in a gas. The paper is bleached white.

(a) Name the gas. [1 mark]

(b) State the test she used. [1 mark]

8. [3 marks] Describe how you would test a gas to show it is ammonia. State the equipment, the method and the positive result.

✍️ Use this frame: "I would hold damp ______ litmus paper near the gas. If it is ammonia, the litmus turns ______."

Independent Work – Middle (Grades 2–3)

Multiple Choice & Short Answer

1. Why must the litmus paper be DAMP for the NH₃ and Cl₂ tests?

2. State the difference between the litmus paper results for ammonia and chlorine.

3. Explain why litmus paper must be damp when testing for ammonia.

4. Why is chlorine tested in a fume cupboard?

Long Answer

5. 🔁 Mixed revision. A student tests four unknown gases. Identify each gas:

Observation	Gas
Glowing splint relights
Limewater turns milky
Damp red litmus turns blue
Damp litmus bleached white

Exam-Style Questions

6. [4 marks] A cleaning product releases a gas that bleaches damp litmus white. (a) Name the gas. [1 mark]

(b) Describe the test and the expected result. [2 marks]

7. [4 marks] Compare the tests for ammonia and chlorine. Explain how you could distinguish between them using damp litmus paper. State what you would observe for each gas and why the results differ.

Independent Work – Higher (Grades 3–5)

Multiple Choice & Short Answer

1. Explain why ammonia turns damp red litmus blue — name the solution formed.

2. Explain why chlorine initially turns damp blue litmus red before bleaching it white.

3. Ammonia dissolves in the moisture on the litmus to form an alkaline solution. Name this solution and the ion responsible for turning the litmus blue.

Long Answer

4. A chemist has an unlabelled jar of gas she believes is ammonia. [4 marks]

(a) Describe the test she should use and the equipment needed. [2 marks]

(b) State what she would observe if she is correct, and explain why this happens. [2 marks]

Exam-Style Questions

5. [6 marks] A student has two unlabelled gas jars: one contains ammonia, the other contains chlorine. Describe a plan to identify both gases. For each jar, state the test, the expected observation and the conclusion. Include ONE safety point.

🎯 Examiner wants: each jar = Test → Observation → Conclusion (same test, different results — blue vs bleached white), plus one safety point (Cl₂ is toxic → fume cupboard).

6. [6 marks] 🔁 Mixed revision. A student is given three test tubes, each containing an unknown gas: one is H₂, one is O₂, and one is CO₂. She has a wooden splint, matches and limewater. Describe a systematic method to identify all three. For each step, state the test, the expected observation and the conclusion.

⭐ Grade 5 stretch: Write the mark scheme for Q5 — exactly where do the six marks sit? Compare with a partner.

Exit Ticket – Foundation (U–1)

1) What colour does damp red litmus turn in ammonia?

2) What does chlorine do to damp litmus paper?

3) Both gases are tested with the same equipment — what is it?

Exit Ticket – Middle (2–3)

1) How do you tell ammonia apart from chlorine using damp litmus?

2) Why must the litmus paper be damp?

3) State one safety precaution when testing chlorine, and why.

Exit Ticket – Higher (3–5)

1) Explain why ammonia turns damp red litmus blue. Name the solution formed.

2) Describe what happens when damp blue litmus is held in chlorine. Explain why.

3) Cl₂ + H₂O → HCl + HClO: which product bleaches, and what does the other product explain?

Gas Tests II: NH₃ & Cl₂

🖨️ Pupil Packs

Arrival Task – Recall from Last Lesson

1. Hydrogen

2. Oxygen

3. Carbon dioxide

4. Today's Lead-in 🔬

1. The splint test

2. Name the gas

3. Spot the correct one

4. Today's Lead-in 🔬

1. From memory

2. Pick the right word

3. Why damp?

4. Today's Lead-in 🔬 — predict

Starter: Two Predictions Left 🔮 (3 mins)

Observe: The Litmus Tests For Real 👀

I Do: Testing for NH₃ and Cl₂

Ammonia

Chlorine

Ammonia vs Chlorine – Litmus Paper

We Do: Build the Answer 🧱🔬

Independent Work

Exit Ticket

Knowledge Organiser – Lesson 4b: Gas Tests II (NH₃ & Cl₂)

Arrival Task — Recall from Last Lesson

Foundation

Middle

Higher

Gas Test Table — fill in during the lesson

We Do: Build the Answer

Scaffolding Sheet

All Five Gas Tests

Common Mistakes

📝 Word Bank (Foundation)

✍️ Sentence Starters

📙 Explain-It Toolkit (Middle)

Chemistry Behind the Tests (Higher)

Independent Work – Foundation (Grades U–1)

Multiple Choice & Short Answer

Long Answer

Exam-Style Questions

Independent Work – Middle (Grades 2–3)

Multiple Choice & Short Answer

Long Answer

Exam-Style Questions

Independent Work – Higher (Grades 3–5)

Multiple Choice & Short Answer

Long Answer

Exam-Style Questions

Exit Ticket – Foundation (U–1)

Exit Ticket – Middle (2–3)

Exit Ticket – Higher (3–5)

🧑‍🏫 TA Focus —

📋 Teacher Notes —

🎯 Cold Call

🎉 Lesson Complete!