1. Chemical synthesis
Lesson 7

2. Reaction was slow at the start and then speeded up
Reaction was fast at the start then slowed down.
Rate of reaction remained constant throughout the experiment.
Volume of gas produced (ml)
Time (s)
Draw rate graphs for each scenario (use axis given)
Which graph would you expect to see for a rates of reaction experiment?
How would you calculate the rate of the reaction?

3. Learning objective: To understand how the rate of a reaction can be measured.
Must: Know different methods for measuring the rate of a reaction. Grade D
Should: Be able to plot a rate of reaction graph. Grade C
Could: Interpret a rate of reaction graph. Grade B
Keywords: Volume, mass, precipitate, plot, horizontal, steep and gradient.

4. Key Skills Numeracy Use appropriate mathematical procedures.
Examine patterns and relationships.
Interpret results and solutions.

5. What can you measure? You can either measure;
1. The amount of product formed or,
2. The amount of reactant used up.
This is the dependent variable.
What is the independent variable?
Time.

6. The three methods. 1. Volume of gas produced. 2. Change in mass.
3. Precipitate formed – a precipitate is an insoluble solid.

7. Volume of gas produced.

8. Loss of mass.
Why is there a loss
of mass?
A gas is being
produced.

9. Precipitate formed.
As the reaction proceeds more precipitate is formed and the
solution becomes cloudier until the cross cannot be seen.
This reaction is known as the disappearing cross experiment.

10. Interpreting graphs When is the reaction fastest?
2. When does the reaction
slow down?
3. From the graph how do
you know the reaction
has stopped?
4. At what time does the
reaction stop?
5. What volume of gas is
produced?