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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. Zinc reacts with hydrochloric acid. What are the products? (zinc oxide + hydrogen / zinc chloride + water / zinc chloride + hydrogen / zinc sulfate + hydrogen) → zinc chloride + hydrogenPrompt: acid + metal → salt + hydrogen
  2. Sodium carbonate reacts with nitric acid. What are the products? (sodium nitrate + hydrogen / sodium carbonate + water / sodium nitrate + water / sodium nitrate + water + carbon dioxide) → sodium nitrate + water + carbon dioxidePrompt: Carbonates fizz with acids. Which gas turns limewater cloudy?
  3. People take antacid tablets containing calcium carbonate for indigestion. How do they work? (They neutralise excess stomach acid / They add more acid / They make food digest faster / They kill all stomach bacteria) → They neutralise excess stomach acidPrompt: Carbonates react 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: bubbled through limewater, it turns it milky? (hydrogen / oxygen / carbon dioxide / chlorine) → carbon dioxidePrompt: Each common gas has its own test.
  2. A gas puts out a lighted splint and turns limewater milky. What is it? (carbon dioxide / oxygen / chlorine / hydrogen) → carbon dioxidePrompt: Fire extinguishers sometimes contain this gas.

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. Which gas gives this result: bubbled through limewater, it turns it milky? (hydrogen / oxygen / carbon dioxide / chlorine) → carbon dioxidePrompt: Each common gas has its own test.
  2. Tests for gases: which statement is NOT true? (Hydrogen gives a squeaky pop with a lighted splint. / Chlorine turns limewater milky. / Oxygen relights a glowing splint. / Limewater is a solution of calcium hydroxide.) → 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

    Which gas gives this result: a glowing splint relights?

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

  2. Question 2

    Hydrogen peroxide decomposes with a catalyst and the gas relights a glowing splint. Which gas is it?

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

  3. Question 3

    Tests for gases: which statement is NOT true?

    • A. Hydrogen gives a squeaky pop with a lighted splint.
    • B. Oxygen gives a squeaky pop.
    • C. Oxygen relights a glowing splint.
    • D. Limewater is a solution of calcium hydroxide.

  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

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

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

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Answer key: Identify gases with laboratory tests

  1. 1. B. oxygen

  2. 2. C. oxygen

  3. 3. B. Oxygen gives a squeaky pop.

  4. 4. D. chlorine

  5. 5. A. limewater turns milky

  6. 6. A. Chlorine is toxic