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Science lesson plan · 9th grade (Year 10 in England) · 30 minutes

Identify gases with laboratory tests

Chemical reactions, acids and bases

CCSS NGSS.HS-PS1-2CCSS NGSS.SEP 3England: GCSE Combined Science: Chemical analysis

Objective and success criteria

Students will: Identify gases with laboratory tests.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: What acids make with metals and carbonates

Leads to: Identify metal ions with flame tests and precipitates

Materials: Teacher demo or video, Indicator color chart, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 4 min

  • Quick retrieval from earlier learning (What acids make with metals and carbonates). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Calcium reacts with nitric acid. What are the products? (calcium nitrate + water / calcium nitrate + carbon dioxide / calcium nitrate + hydrogen / calcium chloride + hydrogen) → calcium nitrate + hydrogenPrompt: acid + metal → salt + hydrogen
  2. Sodium carbonate reacts with sulfuric acid. What are the products? (sodium oxide + carbon dioxide / sodium carbonate + water / sodium sulfate + hydrogen / sodium sulfate + water + carbon dioxide) → sodium sulfate + water + carbon dioxidePrompt: Carbonates fizz with acids. Which gas turns limewater cloudy?
  3. Acid rain slowly damages limestone and marble statues. Why? (They are alkali metals / They are calcium carbonate, which reacts with acids / Rain makes them grow / They are made of iron) → They are calcium carbonate, which reacts with acidsPrompt: What do carbonates do with acids?

Hook · 3 min

  • Drop an antacid tablet in water (or show a clip) and ask whether a new substance is being made.
  • Share the objective: Identify gases with laboratory tests. Read the success criteria together.

I do: model it · 7 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: Which gas gives this result: bubbled through limewater, it turns it milky?
  • Step 1: Carbon dioxide turns limewater milky (cloudy).
  • Step 2: So the answer is: carbon dioxide
  • Answer: carbon dioxide
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 6 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. Which gas gives this result: a lighted splint gives a squeaky pop? (hydrogen / oxygen / carbon dioxide / chlorine) → hydrogenPrompt: Each common gas has its own test.
  2. Hydrogen peroxide decomposes with a catalyst and the gas relights a glowing splint. Which gas is it? (oxygen / hydrogen / carbon dioxide / chlorine) → oxygenPrompt: Hydrogen peroxide is H₂O₂.

You do: independent practice · 7 min

  • Students work on the student sheet. Circulate and check the first two answers of every student early.
  • Students who finish: write a question of their own for a partner, with the answer.

The 6 questions are on the student sheet below, with answers in the key.

Exit ticket · 3 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Why must the chlorine test be done in a fume cupboard? (Chlorine is toxic / Chlorine is radioactive / Chlorine explodes / Chlorine is invisible) → Chlorine is toxicPrompt: Think about safety.
  2. Tests for gases: which statement is NOT true? (Limewater is a solution of calcium hydroxide. / Oxygen relights a glowing splint. / Hydrogen gives a squeaky pop with a lighted splint. / Chlorine turns limewater milky.) → Chlorine turns limewater milky.Prompt: Which gas pops and which relights a splint?

Watch out for

  • Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
  • Remembering facts without the reason: ask "why?" and "what is the evidence?"

Support and stretch

Support

  • Review first: What acids make with metals and carbonates.
  • Use concrete materials: teacher demo or video.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Move on to: Identify metal ions with flame tests and precipitates.
  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-9.

Free lesson plan from eurekami.com/lesson-plan-builder

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Identify gases with laboratory tests

Name

Date

Score/ 6

  1. Question 1

    Tests for gases: which statement is NOT true?

    • A. Hydrogen gives a squeaky pop with a lighted splint.
    • B. Chlorine may turn damp blue litmus red before bleaching it.
    • C. Oxygen gives a squeaky pop.
    • D. Oxygen relights a glowing splint.

  2. Question 2

    Which gas gives this result: a lighted splint gives a squeaky pop?

    • A. hydrogen
    • B. oxygen
    • C. carbon dioxide
    • D. chlorine

  3. Question 3

    Why must the chlorine test be done in a fume cupboard?

    • A. Chlorine is toxic
    • B. Chlorine is invisible
    • C. Chlorine explodes
    • D. Chlorine is radioactive

  4. Question 4

    Which gas gives this result: damp litmus paper is bleached white?

    • A. hydrogen
    • B. oxygen
    • C. carbon dioxide
    • D. chlorine

  5. Question 5

    Marble chips fizz in acid. Which test identifies the gas made?

    • A. limewater turns milky
    • B. a glowing splint relights
    • C. damp litmus is bleached
    • D. a lighted splint pops

  6. Question 6

    Which gas gives this result: bubbled through limewater, it turns it milky?

    • A. hydrogen
    • B. oxygen
    • C. carbon dioxide
    • D. chlorine

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Answer key: Identify gases with laboratory tests

  1. 1. C. Oxygen gives a squeaky pop.

  2. 2. A. hydrogen

  3. 3. A. Chlorine is toxic

  4. 4. D. chlorine

  5. 5. A. limewater turns milky

  6. 6. C. carbon dioxide