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Science lesson plan · 9th grade (Year 10 in England) · 60 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 · 6 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 sulfuric acid. What are the products? (calcium sulfate + carbon dioxide / calcium sulfate + hydrogen / calcium chloride + hydrogen / calcium oxide + hydrogen) → calcium sulfate + hydrogenPrompt: acid + metal → salt + hydrogen
  2. Magnesium carbonate reacts with hydrochloric acid. What are the products? (magnesium chloride + water / magnesium chloride + water + carbon dioxide / magnesium chloride + hydrogen / magnesium oxide + carbon dioxide) → magnesium chloride + water + carbon dioxidePrompt: Carbonates fizz with acids. Which gas turns limewater cloudy?
  3. Acid rain slowly damages limestone and marble statues. Why? (They are made of iron / They are calcium carbonate, which reacts with acids / Rain makes them grow / They are alkali metals) → They are calcium carbonate, which reacts with acidsPrompt: What do carbonates do with acids?

Hook · 6 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 · 12 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 · 12 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? (hydrogen / chlorine / oxygen / carbon dioxide) → oxygenPrompt: Hydrogen peroxide is H₂O₂.

You do: independent practice · 17 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 8 questions are on the student sheet below, with answers in the key.

Exit ticket · 7 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Hydrogen peroxide decomposes with a catalyst and the gas relights a glowing splint. Which gas is it? (chlorine / oxygen / carbon dioxide / hydrogen) → oxygenPrompt: Hydrogen peroxide is H₂O₂.
  2. Tests for gases: which statement is NOT true? (Oxygen relights a glowing splint. / Carbon dioxide relights a glowing splint. / Chlorine may turn damp blue litmus red before bleaching it. / Limewater is a solution of calcium hydroxide.) → Carbon dioxide relights a glowing splint.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/ 8

  1. Question 1

    Which gas gives this result: a glowing splint relights?

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

  2. Question 2

    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. Carbon dioxide relights a glowing splint.
    • D. Limewater is a solution of calcium hydroxide.

  3. Question 3

    A gas puts out a lighted splint and turns limewater milky. What is it?

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

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

  6. Question 6

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

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

  7. Question 7

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

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

  8. Question 8

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

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

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Answer key: Identify gases with laboratory tests

  1. 1. B. oxygen

  2. 2. C. Carbon dioxide relights a glowing splint.

  3. 3. B. carbon dioxide

  4. 4. D. chlorine

  5. 5. D. limewater turns milky

  6. 6. A. hydrogen

  7. 7. C. carbon dioxide

  8. 8. D. Chlorine is toxic