The rate of a chemical reaction: including graphs
Lesson details
Learning outcome
I can describe what happens during a chemical reaction as it progresses over time and interpret graphs showing how the instantaneous rate of the reaction changes.
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.
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.
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.
Teacher tip
This lesson could be used to practise graph drawing skills. If provided with data, students could plot their own graphs and use these to calculate the mean and instantaneous rate of reaction.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Identify the products in this chemical reaction:
magnesium + sulfuric acid → magnesium sulfate + hydrogen
Q2.What do we call the speed with which a chemical reaction takes place?
Q3.Which of the following reactions has a relatively low rate of reaction?
Q4.How do we calculate the gradient of a straight-line graph?
Q5.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
Q6.Given the following data for four different reactions, which reaction has the lowest rate of reaction?
Assessment exit quiz
6 Questions
Q1.How do most chemical reactions progress over time?
Q2.What is the rate of a chemical reaction equal to?
Q3.Match the keywords with the correct definition.
the rate in which reactants form products in a given period of time
the rate in which reactants form products at a specific moment in time
a straight line that touches a curve at exactly one point
represents the rate at which one quantity changes relative to another
Q4.Why is drawing a tangent useful on a rate of reaction graph?
Q5.Which of the following can be plotted to represent the changing rate of a chemical reaction?
Q6.A chemical reaction produces 0.5 g of gas in 10 seconds. What is the correct rate of reaction?
To help you plan your 10 chemistry lesson on: The rate of a chemical reaction: including graphs, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 10 chemistry lesson on: The rate of a chemical reaction: including graphs, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 chemistry lessons from the Rate of reaction unit, dive into the full secondary chemistry curriculum, or learn more about lesson planning.