| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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The rate of a chemical reaction can be found by measuring the quantity of a reactant used or the quantity of product formed over time: mean rate of reaction = quantity of reactant used / time taken OR mean rate of reaction = quantity of product formed / time taken |
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How can the rate of a chemical reaction be calculated? Demo - iodine clock reaction with 5 student helpers
time how long to react.
sketch/plot a graph of results to work out rate from graph or calculate direct from results |
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The quantity of reactant or product can be measured by the mass in grams or by a volume in cm3. |
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How is the quantity of a reactant or product measured? Focus on gas collection (RP skills)
React CaCO3 with dilute HCl and measure the volume of CO2 evolved against time. IV - number of marble chips or volume of acid.
Calculate rate by mass of chips / time taken or volume or gas / time taken.
Record the results and plot a graph of results of volume of gas against time. |
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The units of rate of reaction may be given as g/s or cm3/s. |
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What are the units for rate of reaction? Explain what is meant by the units:
• g/s
• cm3/s
• mol/s. |
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Students are also required to use quantity of reactants in terms of moles and units for rate of reaction in mol/s. (HT only) |
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(HT only) What is the third unit that is used to measure the rate of reaction in terms of moles? Extended writing: write instructions to another student how to calculate the mean rate of reaction. |
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Students should be able to calculate the mean rate of a reaction from given information about the quantity of a reactant used or the quantity of a product formed and the time taken |
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What would the total amount of a product formed if the rate of reaction is 4g/s and the reaction continues for 3 minutes? |
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Students should be able to draw, and interpret, graphs showing the quantity of product formed or quantity of reactant used up against time |
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What key features must be included for graphs showing the quantity of product formed or quantity of reactant used up against time? Analyse graphical data on ppt to identify and explain
ie:
•initially rate is fast
•slows down
•reaction completion
Go further: complete the measuring rate of reaction worksheet. |
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Students should be able to draw tangents to the curves on these graphs and use the slope of the tangent as a measure of the rate of reaction |
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How do you draw a tangent on a curve to measure the rate of a reaction on a graph? |
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Students should be able to (HT only) calculate the gradient of a tangent to the curve on these graphs as a measure of rate of reaction at a specific time. |
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(HT only) How do you calculate the gradient of a tangent of a curve from a graph? Get students to calculate the gradient from graphs they have analysed using tangents. |
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