Starter quiz
- Identify the products in this chemical reaction: magnesium + sulfuric acid → magnesium sulfate + hydrogen
- magnesium
- sulfuric acid
- magnesium sulfide
- magnesium sulfate ✓
- hydrogen ✓
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- What do we call the speed with which a chemical reaction takes place?
- speed of reaction
- velocity of reaction
- rate of reaction ✓
- intensity of reaction
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- Which of the following reactions has a relatively low rate of reaction?
- combustion of petrol
- incomplete combustion of alkanes
- rusting of iron ✓
- neutralisation of an acid and alkali
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- How do we calculate the gradient of a straight-line graph?
- divide the change in time by the change in volume
- multiply the change in y-axis value by the change in x-axis value
- divide the change in y-axis value by the change in x-axis value ✓
- add the change in y-axis value to the change in x-axis value
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- A graph shows the volume of gas produced (in cm³) over time (in seconds). If the graph has a straight line that rises from 0 cm³ at 0 seconds to 40 cm³ at 20 seconds, what is the gradient of the graph
- 0.5 cm³/s
- 2 cm³/s ✓
- 20 cm³/s
- 40 cm³/s
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- Given the following data for four different reactions, which reaction has the lowest rate of reaction?
- reaction 1 produces 5 cm³ of gas in 10 seconds
- reaction 2 produces 10 cm³ of gas in 20 seconds
- reaction 3 produces 15 cm³ of gas in 30 seconds
- reaction 4 produces 5 cm³ of gas in 20 seconds ✓
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Exit quiz
- How do most chemical reactions progress over time?
- they start slowly and speed up
- they maintain a constant speed
- they start quickly and slow down ✓
- they stop and start repeatedly
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- What is the rate of a chemical reaction equal to?
- the total amount of product formed
- the amount of product formed per unit time ✓
- the amount of reactant used per unit time ✓
- the total time taken for the reaction
- the initial amount of reactant
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- Match the keywords with the correct definition.
- mean rate of reaction⇔the rate in which reactants form products in a given period of time ✓
- instantaneous rate of reaction⇔the rate in which reactants form products at a specific moment in time ✓
- tangent⇔a straight line that touches a curve at exactly one point ✓
- gradient⇔represents the rate at which one quantity changes relative to another ✓
- Why is drawing a tangent useful on a rate of reaction graph?
- it shows the total amount of reactant used
- it helps find the instantaneous rate at a specific moment ✓
- it measures the temperature change over time
- it calculates the mean rate of reaction
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- Which of the following can be plotted to represent the changing rate of a chemical reaction?
- time versus temperature
- mass versus time ✓
- pressure versus concentration
- concentration versus time ✓
- volume versus concentration
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- A chemical reaction produces 0.5 g of gas in 10 seconds. What is the correct rate of reaction?
- 0.05 grams
- 10 seconds
- 0.05 grams per second ✓
- 0.05 seconds per gram
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Most chemical reactions start more quickly and slow down as they progress.
- The rate of a chemical reaction is equal to the amount of product formed per unit time (or reactant used per unit time).
- The mean rate of a chemical reaction is different to the instantaneous rate that changes throughout the reaction.
- Graphs of mass, volume, or concentration vs. time can all represent the changing rate of a chemical reaction.
- The gradient of a rate of reaction graph can be calculated from a tangent drawn at a point on the curve.
Common misconception
To calculate the instantaneous rate of reaction by reading values from the graph at a specific time.
Students need to draw a tangent in order to calculate the gradient of the graph at a specific time to work out the instantaneous rate of reaction.
Keywords
Rate of reaction - Rate of reaction is the speed with which a chemical reaction takes place.
Mean rate of reaction - The mean rate of reaction is the average rate at which reactants are converted into products over a given period of 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.
Gradient - The gradient on a graph represents the rate at which one quantity changes relative to another.
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