Starter quiz
- If you want to make a solid react faster with a liquid, what should you do to the solid?
- dilute the liquid
- break the solid into smaller pieces ✓
- compress the solid
- cool the solid
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- Why do smaller particles of a solid react faster than larger particles of the same solid?
- they have a lower mass
- they have a smaller volume
- they have a larger surface area ✓
- they have a higher density
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- Which has a greater surface area to volume ratio: 5g of large calcium carbonate chips, 5g of small calcium carbonate chips or 5g of powdered calcium carbonate?
- 5g of large calcium carbonate chips
- 5g of small calcium carbonate chips
- 5g of powdered calcium carbonate ✓
- they all have the same surface area
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- Why is it important to control variables in a rate of reaction experiment?
- to change the outcome of the experiment
- to ensure the experimental results are reliable ✓
- to increase the reaction rate
- to decrease the reaction rate
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- Which of the following should be kept constant in an experiment investigating the effect of surface area on reaction rate?
- the surface area of a solid reactant
- the concentration of a reacting solution ✓
- the volume of gas produced
- the time taken for the reaction to reach completion
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- What will we have calculated if we divide the amount of product made by the time taken?
- concentration of a reacting solid
- temperature of the reaction mixture
- mass of catalyst added
- mass of reacting solid needed for the reaction to reach completion
- rate of reaction ✓
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Exit quiz
- What will we calculate if we determine the gradient at a specific point on a graph of mass of product versus time.
- mean rate of reaction
- instantaneous rate of reaction ✓
- tangent
- concentration of reacting solution
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- On a graph of mass of gas produced against time, what does a steeper gradient indicate?
- a higher rate of reaction ✓
- a lower rate of reaction
- no reaction occurring
- constant rate of reaction
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- Why does the surface area of marble chips affect the rate of reaction but not the total mass of gas produced?
- surface area changes the concentration of acid
- surface area affects the frequency of collisions ✓
- surface area changes the mass of acid used
- surface area has no effect on reaction rate
- the marble chips are the limiting reactant
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- How is the mean rate of reaction calculated?
- total mass of gas produced × total time of reaction
- total time of reaction ÷ total mass of gas produced
- total mass of gas produced ÷ total time of reaction ✓
- total mass of reactants × total time of reaction
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- If 30 grams of gas are produced in 10 minutes, what is the mean rate of reaction?
- 3 grams per minute ✓
- 30 grams per minute
- 0.3 grams per minute
- 10 grams per minute
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- When reacting excess marble chips with acid, how does the surface area of the chips affect the total mass of gas produced?
- more gas is produced with larger chips
- less gas is produced with smaller chips
- the same mass of gas is produced for all surface areas ✓
- no gas is produced with smaller chips
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- The changing rate of a chemical reaction can be represented by a graph of mass of gas produced against time.
- When reacting excess marble chips with acid, the same mass of gas is produced for all surface areas of chips.
- The mean rate of reaction = total mass of gas produced ÷ total time of reaction
- The instantaneous rate of reaction is equal to the gradient of the graph.
- The gradient of a rate of reaction graph can be calculated from a tangent drawn at a point on the curve.
Common misconception
Pupils often confuse the mean rate of reaction with the instantaneous rate of reaction, thinking they are the same or not understanding the distinction between the two.
The tasks give pupils s the opportunity to distinguish between mean and instantaneous rate of reaction by calculating both from the same set of data.
Keywords
Gradient - The gradient on a graph represents the rate at which one quantity changes relative to another.
Mean rate of reaction - The mean rate of reaction is the average rate at which reactants are converted into products in a given time.
Instantaneous rate of reaction - The instantaneous rate of reaction is the rate at which reactants are converted into products at a specific moment in time.
Tangent - A tangent is a straight line that touches a curve at exactly one point without crossing it.
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