Measuring Reaction Rates

Name:

Date:

Chemical reaction rate measurement illustration

📊 Part 1: Understanding Rate Measurements

1. Which of these methods can be used to measure reaction rates? (Tick all that apply)

Measuring mass loss over time

Measuring gas volume produced over time

Observing colour changes over time

Measuring temperature changes only

2. A student measures the volume of gas produced in a reaction. After 2 minutes, 24 cm³ of gas has been collected. What is the average rate of gas production?

12 cm³/min

24 cm³/min

48 cm³/min

6 cm³/min

3. When is a chemical reaction fastest?

At the beginning when reactant concentration is highest

In the middle of the reaction

At the end when products have formed

The rate stays constant throughout

4. Complete this sentence: "The steeper the gradient on a concentration-time graph, the _________ the reaction rate."

Answer: _________________

📈 Part 2: Graph Analysis

Study the data below from a reaction where magnesium ribbon reacts with hydrochloric acid:

Time (min): 0, 1, 2, 3, 4, 5
Gas volume (cm³): 0, 15, 25, 32, 36, 36

5. Plot this data on the grid provided and draw a smooth curve through the points.

6. At what time does the reaction appear to finish? Explain how you can tell from the graph.

7. During which time interval is the reaction fastest? Circle your answer and explain why.

0-1 minutes

1-2 minutes

2-3 minutes

4-5 minutes

Explanation: ________________________________________________

8. Calculate the average rate of gas production between 0 and 2 minutes. Show your working.

🔬 Part 3: Application and Analysis

9. A pharmaceutical company needs to measure how quickly a medicine dissolves. Suggest two different methods they could use and explain one advantage of each method.

10. Extension Challenge: If you increased the temperature of the magnesium and acid reaction, sketch how you think the new graph would compare to your original graph. Label both lines clearly.

11. Higher Level: Explain why reaction rates typically decrease over time, using the collision theory to support your answer.

Support Notes: Remember that reaction rate depends on how often reactant particles collide with enough energy. Consider what happens to reactant concentration as a reaction progresses.