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Science lesson plan · 10th grade (Year 11 in England) · 45 minutes

Calculate mean rates of reaction from data

Chemical reactions, acids and bases

CCSS NGSS.HS-PS1-5CCSS NGSS.SEP 5England: GCSE Combined Science: The rate and extent of chemical change

Objective and success criteria

Students will: Calculate mean rates of reaction from data.

  • 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: Rates of reaction

Leads to: the next skill in this area.

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 · 5 min

  • Quick retrieval from earlier learning (Rates of reaction). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. A reaction produces 30 cm³ of gas in 60 seconds. What is the mean rate of reaction, in cm³/s? → 0.5 cm³/sPrompt: mean rate = amount of product ÷ time
  2. Why does powdered marble react faster with acid than marble chips? (Powder has more mass / Chips are hotter / Powder is a different substance / Powder has a larger surface area, so there are more collisions) → Powder has a larger surface area, so there are more collisionsPrompt: Cutting something up exposes more of it.
  3. Rates of reaction: which statement is NOT true? (Lower temperatures make reactions faster. / A catalyst is not used up in a reaction. / Food lasts longer in a fridge because reactions are slower at low temperature. / Increasing surface area increases the rate.) → Lower temperatures make reactions faster.Prompt: What does a catalyst change, and what does it not change?

Hook · 5 min

  • Drop an antacid tablet in water (or show a clip) and ask whether a new substance is being made.
  • Share the objective: Calculate mean rates of reaction from data. Read the success criteria together.

I do: model it · 10 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: Magnesium reacted with acid and 24 cm³ of hydrogen was collected in 20 s. What was the mean rate of reaction, in cm³/s?
  • Step 1: 24 ÷ 20 = 1.2
  • Step 2: So the answer is: 1.2 cm³/s
  • Answer: 1.2 cm³/s
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 10 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. Magnesium reacted with acid and 8 cm³ of hydrogen was collected in 10 s. What was the mean rate of reaction, in cm³/s? → 0.8 cm³/sPrompt: mean rate = amount of product formed ÷ time taken
  2. Marble chips and acid were placed on a balance. The mass fell from 162.4 g to 161.2 g in 200 s as carbon dioxide escaped. What was the mean rate of reaction, in g/s? Give 3 decimal places. → 0.006 g/sPrompt: First find the mass of gas lost.

You do: independent practice · 10 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 · 5 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Volume of gas collected: 0 s: 0 cm³; 20 s: 33 cm³; 40 s: 48 cm³; 60 s: 55 cm³; 80 s: 58 cm³; 100 s: 59 cm³. What was the mean rate between 0 s and 40 s, in cm³/s? Give 2 decimal places. → 1.2 cm³/sPrompt: Find the change in volume over that time interval.
  2. Marble chips and acid were placed on a balance. The mass fell from 180 g to 179.4 g in 300 s as carbon dioxide escaped. What was the mean rate of reaction, in g/s? Give 3 decimal places. → 0.002 g/sPrompt: First find the mass of gas lost.

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: Rates of reaction.
  • 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

  • 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-10.

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

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Calculate mean rates of reaction from data

Name

Date

Score/ 8

  1. Question 1

    Magnesium reacted with acid and 16 cm³ of hydrogen was collected in 20 s. What was the mean rate of reaction, in cm³/s?

    Answercm³/s

  2. Question 2

    Volume of gas collected: 0 s: 0 cm³; 20 s: 18 cm³; 40 s: 28 cm³; 60 s: 33 cm³; 80 s: 36 cm³; 100 s: 38 cm³. What was the mean rate between 60 s and 80 s, in cm³/s? Give 2 decimal places.

    Answercm³/s

  3. Question 3

    Marble chips and acid were placed on a balance. The mass fell from 150 g to 149.4 g in 150 s as carbon dioxide escaped. What was the mean rate of reaction, in g/s? Give 3 decimal places.

    Answerg/s

  4. Question 4

    Magnesium reacted with acid and 40 cm³ of hydrogen was collected in 20 s. What was the mean rate of reaction, in cm³/s?

    Answercm³/s

  5. Question 5

    Volume of gas collected: 0 s: 0 cm³; 20 s: 33 cm³; 40 s: 48 cm³; 60 s: 55 cm³; 80 s: 58 cm³; 100 s: 59 cm³. What was the mean rate between 40 s and 80 s, in cm³/s? Give 2 decimal places.

    Answercm³/s

  6. Question 6

    Marble chips and acid were placed on a balance. The mass fell from 120 g to 118.5 g in 60 s as carbon dioxide escaped. What was the mean rate of reaction, in g/s? Give 3 decimal places.

    Answerg/s

  7. Question 7

    Magnesium reacted with acid and 12 cm³ of hydrogen was collected in 10 s. What was the mean rate of reaction, in cm³/s?

    Answercm³/s

  8. Question 8

    Volume of gas collected: 0 s: 0 cm³; 20 s: 38 cm³; 40 s: 52 cm³; 60 s: 57 cm³; 80 s: 59 cm³; 100 s: 60 cm³. What was the mean rate between 20 s and 60 s, in cm³/s? Give 2 decimal places.

    Answercm³/s

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Answer key: Calculate mean rates of reaction from data

  1. 1. 0.8 cm³/s

  2. 2. 0.15 cm³/s

  3. 3. 0.004 g/s

  4. 4. 2 cm³/s

  5. 5. 0.25 cm³/s

  6. 6. 0.025 g/s

  7. 7. 1.2 cm³/s

  8. 8. 0.48 cm³/s