Surface area and rate: analysis
Lesson details
Learning outcome
I can represent graphically and describe how the rate of reaction depends on the surface area of a solid reactant.
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.
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.
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.
Teacher tip
Provide additional guidance to pupils who need extra support on how to draw a tangent.
Equipment
Graph paper for drawing graphs. Ruler or straight edge to draw tangents. Calculator to calculate rate of reaction.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.If you want to make a solid react faster with a liquid, what should you do to the solid?
Q2.Why do smaller particles of a solid react faster than larger particles of the same solid?
Q3.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?
Q4.Why is it important to control variables in a rate of reaction experiment?
Q5.Which of the following should be kept constant in an experiment investigating the effect of surface area on reaction rate?
Q6.What will we have calculated if we divide the amount of product made by the time taken?
Assessment exit quiz
6 Questions
Q1.What will we calculate if we determine the gradient at a specific point on a graph of mass of product versus time.
Q2.On a graph of mass of gas produced against time, what does a steeper gradient indicate?
Q3.Why does the surface area of marble chips affect the rate of reaction but not the total mass of gas produced?
Q4.How is the mean rate of reaction calculated?
Q5.If 30 grams of gas are produced in 10 minutes, what is the mean rate of reaction?
Q6.When reacting excess marble chips with acid, how does the surface area of the chips affect the total mass of gas produced?
To help you plan your 10 chemistry lesson on: Surface area and rate: analysis, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 10 chemistry lesson on: Surface area and rate: analysis, 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.