Evaluating methods for measuring the rate of reaction
Lesson details
Learning outcome
I can compare different methods for measuring the effect of concentration on the rate of reaction and suggest improvements.
Key learning points
- Measuring volume of gas produced throughout a reaction allows the changing rate of reaction to be calculated.
- Errors in measuring volumes of gas over time include timing, reading volumes in real time and gas displaced by the bung.
- Measuring an end-point in a reaction allows direct and simple comparison of reaction rates.
- Errors in measuring end-points include subjectivity of observations, measuring times and volumes, and contamination.
Keywords
Accuracy - Accuracy refers to how close a measured value is to the true or standard value.
Repeatable - A method is described as repeatable if a person uses the same method and obtains the same/similar results when repeating the experiment.
Parallax error - A parallax error occurs when a measurement is not taken at eye-level.
Systematic error - A systematic error is caused by the equipment used.
Common misconception
Adding a bung to the top of a conical flask does not affect volume measurements.
The bung can displace a small volume of gas, which can affect the accuracy of the measurements. It is essential to account for the volume displaced by the bung in calculations.
Teacher tip
Demonstrate the apparatus set-up to help pupils understand where gas can escape to the surroundings and that the bung displaces gas from the conical flask.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Which method would be most suitable for measuring the rate of a reaction that produces a gas as one of its products?
Q2.How can we measure the amount of gas produced in a chemical reaction?
Q3.Typically what happens to the rate of reaction during a reaction?
Q4.When measuring the volume of gas produced in a chemical reaction, what effect will gas escaping to the surroundings have on the results?
Q5.How can we calculate the instantaneous rate of reaction from a volume of gas produced versus time graph?
Q6.Match the type of error to the correct definition.
occurs when an instrument does not reset to zero
is caused by the equipment used
occurs when a measurement is not taken at eye-level
made by the investigator such as timing incorrectly
Assessment exit quiz
6 Questions
Q1.What is a potential error that could affect the accuracy of end-point measurements?
Q2.What type of error could affect the accuracy of measuring the volume of gas over time?
Q3.Which apparatus set-up can cause errors when measuring volumes of gas produced?
Q4.Why is measuring an end-point in a reaction useful?
Q5.How can you reduce subjectivity in observing the end-point of a reaction?
Q6.Which key term is used for results that are close to the true or standard value?
To help you plan your 11 combined science lesson on: Evaluating methods for measuring the rate of reaction, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 11 combined science lesson on: Evaluating methods for measuring the rate of reaction, 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 combined science lessons from the Rate of reaction unit, dive into the full secondary combined science curriculum, or learn more about lesson planning.