Course
Subject
Topic
Pages
Additional science
Chemistry
C2 4.1 How fast?
Pages 126–127
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 that chemical reactions
can happen at different
rates
 how the rate of a chemical
reaction can be calculated.
Most students should be able to:
 state a definition of the rate of
reaction
 list ways of finding the rate
 suggest a method for finding the
rate in a specified reaction.
Some students should also be
able to:
 explain in detail why a particular
method of finding the rate is
suitable for a specified reaction.
The rate of a chemical reaction can be found by
measuring the amount of a reactant used or the
amount of product formed over time:
 Rate of reaction = amount of reactant used / time
 Rate of reaction = amount of product formed /
time [C2.4.1 a)]
Interpret graphs showing the amount of product
formed (or reactant used up) with time, in terms of
the rate of the reaction. [C2.4]
Controlled Assessment: AS4.3 Collect primary and
secondary data. [AS4.3.2 b) c)]; AS4.5 Analyse and
interpret primary and secondary data. [AS4.5.2 b) d)]
Chapter map:
Rates and energy
Teacher notes:
Rates and energy
Lesson structure
Support, Extend and Practical notes
Starters
Fast or slow – Give each student a piece of paper with ‘fast’ on one side and ‘slow’ on the
other. Then show them different images of chemical reactions, e.g. rusting, baking a cake,
cooking an egg, magnesium reacting with acid and neutralisation. They should look at each
image, decide if the rate is fast or slow and hold up the card to demonstrate their answer.
Images could be shown using a data projector or PowerPoint slides. (5 minutes)
Cut and stick – Explain to students what ‘rate of reaction’ is. Then give the students
different magazines and catalogues. Their task is to cut out an example of a reaction with a
fast rate and a slow rate. They then compare their findings with a small group of students,
and they choose the best from their selection. Students could then make a class montage on
sugar paper. You could support students by giving them some examples of fast and slow
reactions that they could find in the magazines. You could extend students by encouraging
them to represent the reactions as a word or symbol equation. (10 minutes)
Main
In many chemical reactions that we use to study rate, a gas is made. Students should
produce a graph so that they can interpret information about a reaction. Using the reaction
between magnesium and acid, ask students to plot a graph to show the production of
hydrogen over two minutes. Then ask them to annotate their graph to explain the shape.
They should include information that explains why the graph starts at 0 cm 3 of gas and they
should explain the shape of the graph.
The reaction between hydrochloric acid and sodium thiosulfate is the classic example used
to highlight how light can be used to determine the rate of reaction. Students could complete
this experiment themselves and reflect on the technique. Alternatively, this could be
completed as a class demonstration. Draw the black cross on an overhead transparency and
put it onto an overhead projector. Choose a student to be in charge of the stopwatch. Then
put the reaction vessel on to the cross and ask students to raise their hands when they think
the cross has gone. When most of the hands are raised, stop the watch and note the time.
Compare this with using a light sensor and data logger. A plot of the light intensity could be
made. Use this as an opportunity to teach about the ‘Controlled Assessment’ concepts of
reliability, accuracy, and experimental error. The disappearing cross experiment relies on a
person deciding when the cross disappears and this introduces errors, which data logging
can help to address.
There are also opportunities here to show students how to make measurements using
sensors (e.g. carbon dioxide, oxygen, pH, gas pressure and temperature) to investigate
reaction rates.
After the students have watched the demonstration of the reaction between magnesium and
acid, allow them to experiment with the different methods for measuring rate of reaction
detailed in ‘Practical support’. They will need a supply of the hydrochloric acid and
magnesium strips (and eye protection). The aim of this activity is for the students to decide
the most informative method. [They should realise that the balances available are not
sensitive enough (need higher resolution), there is no precipitate formed, so the disappearing
cross is useless, but collection of gas is the most accurate if a gas syringe is used.] You may
wish to use a pH probe to monitor the reactions. You may wish to extend students further by
giving them a selection of equipment to measure the volume of gas such as a gas syringe, a
water trough and a measuring cylinder or burette. Again, encourage students to evaluate the
different methods and decide which would be the most accurate [gas syringe].
Plenaries
Graph interpretation – Show students a graph of the rate of a particular reaction. Ask them
to interpret the graph and explain the shape of the curve. Support students by giving them
graphs on squared paper and with simple numbers. Extend students by using more complex
scales and data points that involve decimals. (5 minutes)
Card sort – Make a set of eight cards: four with diagrams showing how the rate of reaction
can be found (mass change, gas collection by displacement in a measuring cylinder, gas
collection in a gas syringe, disappearing cross) and four with examples of reactions that can
be measured using these techniques (magnesium + acid, calcium carbonate + acid, sodium
thiosulfate + acid, hydrogen peroxide + manganese dioxide). Ask the students to match the
methods with reactions. Encourage them to discuss their work in small groups, then feed
back to the class in a question-and-answer session. [Note: Only the sodium thiosulfate
reaction can be measured using the disappearing cross. (10 minutes)
Support
Some students find graph paper confusing. Therefore
supply these students with squared paper, with the
scales already drawn on. Once the students have plotted
their graph, you could supply these statements (in the
wrong order) for students to copy on to their graph.
 Start of reaction.
 Fast rate of reaction.
 Slow rate of reaction.
 End of reaction.
Extend
Ask students to calculate the gradient at different
points of the graph and actually give a value for the
rate of reaction.
Practical support
Measuring the mass of a reaction mixture
Equipment and materials required
Marble chips, 1 mol/dm3 hydrochloric acid (CLEAPSS
Hazcard 47A), 250 cm3 conical flask, top-pan balance,
cotton wool, stopwatch, measuring cylinder, eye
protection.
Measuring the volume of gas given off
Equipment and materials required
Marble chips, 1 mol/dm3 hydrochloric acid
(CLEAPSS Hazcard 47A), 250 cm3 conical fl ask,
bung fitted with delivery tube, about 50 cm length of
rubber tubing, 100 cm3 gas syringe (ensure syringe
plunger is free moving), gas syringe holder, boss,
stand, stopwatch, measuring cylinder, eye protection.
Measuring the light transmitted through a
solution
Equipment and materials required
Two measuring cylinders, stopwatch, paper with large
cross in the centre, conical flask, beaker, 0.2 mol/dm3
sodium thiosulfate,0.2 mol/dm3 hydrochloric acid (irritant),
eye protection (chemical splashproof goggles).
Safety: During this experiment, sulfur dioxide is
produced which is toxic and can trigger asthmatic
attacks. Therefore this should be completed in a wellventilated room. Once the reaction is complete, the
mixture should be disposed of following CLEAPSS
guidelines in Hazcard 95C. CLEAPSS Hazcard 97
Sulfur dioxide – toxic.
Demonstration of the reaction between
magnesium and acid
Equipment and materials required
Hydrochloric acid (1 mol/dm3) (CLEAPSS Hazcard
47A), strips of 1 cm magnesium ribbon (CLEAPSS
Hazcard 59A), test tube, eye protection.
Text © Ruth Miller, Geoff Carr, Darren Forbes, Sam Holyman 2011
Course
Subject
Topic
Pages
Additional
science
Chemistry
C2 4.2 Collision theory and
surface area
Pages 128–129
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 that different factors affect
the rate of reaction
 what collision theory is
 how collision theory can
be used to explain the
effect of surface area on
the rate of reaction.
Most students should be able to:
 list the factors that affect the
rate of reaction
 recall a definition of collision
theory
 describe how surface area
affects the rate of reaction.
Some students should also be
able to:
 explain in detail collision
theory
 apply collision theory to
explain in detail how surface
area affects the rate of
reaction.
Chemical reactions can only occur when reacting particles
collide with each other and with sufficient energy. The
minimum amount of energy particles must have to react is
called the activation energy. [C2.4.1 b)]
Increasing the surface area of solid reactants increases the
frequency of collisions and so increases the rate of
reaction. [C2.4.1 f)]
Interpret graphs showing the amount of product formed (or
reactant used up) with time, in terms of the rate of the
reaction.
Controlled Assessment: AS4.2 Assess and manage risks
when carrying out practical work. [AS4.2.1 a) b)]; AS4.3 Collect
primary and secondary data. [AS4.3.2 a)]; AS4.4 Select and
process primary and secondary data. [AS4.4.2 c)]
Practical: The
effect of
surface area
on reaction
rate
Lesson structure
Support, Extend and Practical notes
Starters
Labelling – Give students a diagram of the equipment used to monitor the rate
of the reaction of marble (calcium carbonate) with acid, when mass loss is
being measured. Ask them to label the equipment. Support students by giving
them the labels and completing the activity as a ‘cut-and-stick’ exercise.
Extend students by explaining how this equipment could be used to monitor
rate of reaction. (5 minutes)
Thinking – Ask students to work in pairs and list ways of monitoring the rate of
reaction between an acid and a metal [mass loss, gas production]. Then ask
students for ways in which this reaction could be speeded up [heat the acid,
increase the surface area of the metal, increase the concentration of the acid].
(10 minutes)
Main
Magnesium is often found as ribbon or in powdered form in schools. Show the
students samples of each. Ask them to predict which would have the faster
rate of reaction and why (using collision theory to explain). In their prediction,
they should include a word equation (balanced symbol equation for Higher Tier
students) to represent the reaction and what observations they would expect.
They could then complete a risk assessment for the experiment, carry it out
(once checked) and see if their prediction was correct.
Marble chips come in a variety of sizes but each size is within a range. Show
the students samples of different marble chips. Explain that they are going to
investigate the mass lost during this experiment in order to decide how the
surface area affects the rate. Encourage students to consider what the
variables are in the experiment [time, temperature, concentration and volume
of acid, mass of marble].
Students should then decide on the appropriate values of each and detail
which variables should be control variables. The investigation should then be
completed and a conclusion written using collision theory. This provides an
excellent opportunity to cover the investigative aspects of the Controlled
Assessment.
Plenaries
Summarise – Ask the students to make a bullet-point list of facts about
collision theory. (5 minutes)
Demonstration – For this demo you will need an iron nail, iron wool, iron
filings, tongs, a heat-proof mat, a Bunsen burner, spatula, eye protection.
Show students the iron nail, iron wool and iron filings. Ask them what reaction
will happen when the iron is put in the flame and ask for a volunteer to write
the word equation on the board [iron + oxygen → iron oxide]. You could extend
students by asking them to write a balanced symbol equation [4]Fe + [3]O2 →
[2]Fe2O3. Ask the students to predict which will combust most quickly and why.
Support students by encouraging them to use the Student Book and think
about the work that they have completed in the main part of the lesson.
Demonstrate each type of iron in the flame: hold the nail into the blue flame
using tongs; then hold a small piece of iron wool into the flame using tongs;
finally sprinkle a few iron filings from a spatula into the flame. Wear eye
protection. (10 minutes)
Support
Some students will have difficulty with isolating variables. You could
provide the variables and give these students suggested
measurements on separate cards. They could then match the
values with the variables and use this in their experiment. To add to
this activity, the variable that must be kept constant could be written
in one colour, and the independent and dependent variables could
be in another colour. Ask the students what the colour code means.
Extend
Ask students to suggest which collisions would not cause a reaction
(those with insufficient energy, incorrect orientation, two product
particles or a reactant and a product colliding). Students could
illustrate these factors as particle diagrams.
Practical support
Which burns faster – ribbon or powder?
Equipment and materials required
Bunsen burner and safety equipment, 2 cm length of
magnesiumribbon (CLEAPSS Hazcard 59A), magnesium powder
(highly flammable), spatula, tongs, stopwatch, eye protection.
Details
Hold the end of the magnesium ribbon with tongs. Put the tip of the
ribbon in the top of the blue gas cone. As soon as the ribbon
ignites, remove it from the flame and observe. Then sprinkle about
half a spatula of magnesium powder directly into the blue flame
(held at an angle).
Safety: Eye protection should be worn throughout this practical.
Magnesium oxide powder will be made and may enter the air; this could
irritate airways and therefore the reaction should be completed in a wellventilated room. When magnesium ribbon burns, a very bright white light
is produced. This can blind if people look at it directly. Therefore
encourage students to look past the reaction or alternatively use special
blue glass/plastic to mute the light.
Investigating surface area
Equipment and materials required
Conical flask, 1 mol/dm3 dilute hydrochloric acid (CLEAPSS
Hazcard 47A), cotton wool, top-pan balance, marble chips of
different sizes, measuring cylinder, stopwatch, eye protection.
Details
Wash and dry the marble chips (to remove the powder from the
surface). Measure out about 1 g of marble chips of a certain size
into a conical flask. Eye protection should be worn at this point. Add
25 cm3 of acid and put in the cotton wool plug. Put the reaction
vessel on to the top-pan balance and observe the mass change
over time. Repeat the experiment with different sized marble chips.
Control variables are: concentration of acid, volume of acid, mass
of marble, temperature.
Safety: Eye protection should be worn.
Text © Ruth Miller, Geoff Carr, Darren Forbes, Sam Holyman 2011
Course
Subject
Topic
Pages
Additional science
Chemistry
C2 4.3 The effect of temperature
Pages 130–131
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn that:
 that increasing the
temperature affects the
rate of reactions
 how collision theory can
be used to explain how
temperature affects rate of
reaction.
Most students should be able to:
 describe how increasing the
temperature affects the rate of
reactions
 state two reasons why increasing
the temperature increases the rate.
Some students should also be able to:
 use collision theory to explain in
detail how and why increasing the
temperature changes the rate of
reaction.
Increasing the temperature increases the speed
of the reacting particles so that they collide more
frequently and more energetically. This
increases the rate of reaction. [C2.4.1 c)]
Interpret graphs showing the amount of product
formed (or reactant used up) with time, in terms
of the rate of the reaction. [C2.4]
Controlled Assessment: AS4.1 Plan practical
ways to develop and test candidates own
scientific ideas. [AS4.1.1 c)]; AS4.3 Collect
primary and secondary data.
[AS4.3.2 b) c)]; AS4.5 Analyse and interpret
primary and secondary data. [AS4.5.2 b) d)]
Practical: The
effect of
temperature on
reaction rate
Lesson structure
Support, Extend and Practical notes
Starters
Pictionary – Create packs of cards with these statements on:
‘increase temperature’, ‘collision’, ‘particle’, ‘reactant’, ‘product’,
‘rate’, ‘chemical reaction’. Split the students into pairs and give
them a pack of cards. Ask them to take it in turns to pick up the
card and draw a picture (with no text, symbols or numbers) to get
their partner to say the statement or word. (5 minutes)
What is in the bag? – In a bag, put in key words on separate pieces of
paper: ‘collision theory’, ‘temperature’, ‘particles’, ‘collision’, ‘rate’,
‘activation energy’. Then ask for a volunteer to come to the front and
remove a key word. They can then explain what that words means.
Allow students who have difficulty to go back to their seat and look
through the Student Book, then talk to neighbours; invite them back at
the end of the Starter. Extend students by asking them to use the word
correctly in a sentence. In total, ask five volunteers to explain each of
the words in turn. (10 minutes)
Main
Students could experimentally determine the effect of temperature
on rate of reaction by using the sodium thiosulfate reaction. As a
class, decide on five temperatures that will be used – the
maximum temperature should be 50 ºC to minimise any sulfur
dioxide liberated. In small groups each temperature is completed
once, but then three groups (or the whole class) could pool their
results and take a mean, making the results more reliable.
Students could plot a graph, drawing a line of best fit. They should
then use their graph and their knowledge of collision theory to
draw a conclusion. This provides an opportunity to cover the
investigative aspects of the Controlled Assessment.
Ask students to draw a cartoon to show the effect of heating up a
reaction in terms of its rate. Students could be encouraged to personify
the particles and make a fun depiction of the reaction. To help them, the
cartoon framework could be given with statements to include in a box
below their images, to explain what is happening.
Ensure that students understand the two reasons why increasing
the temperature increases the rate of reaction. Some students will
quote the increased frequency of collisions but fail to mention the
greater proportion of collisions with energy greater than the
activation energy in examination questions.
Plenaries
Spot the mistake – Ask students to spot the error in the following
sentence: ‘When temperature is dropped, particles have more
energy but move around less and so the rate of reaction stays the
same.’ [When temperature is dropped, the particles have less
energy and the rate of reaction will decrease.] (5 minutes)
Sentences – In small groups ask the students to finish the
following sentence: ‘As you heat up a reaction ...’
After a few minutes ask the groups to read out their finished sentences.
Then choose the most scientific sentence and give that group a prize.
Support students by giving them a selection of endings for the sentence
– some correct, some incorrect and some more scientific than others.
Encourage students to select which ending they want to use from the
list. Extend students by asking them to draw a labelled diagram to
illustrate their sentence. (10 minutes)
Support
Some students will have difficulty in understanding the link between rate of
reaction and temperature. Using a familiar situation can help students to
understand abstract concepts more easily. Link temperature and rate of
reaction with dissolving sugar into tea. Ask students to predict which cup of tea
will dissolve sugar the quickest. This physical change could be demonstrated or
carried out by the students. Each group from the class could put its results from
the thiosulfate experiment into spreadsheet. This could then be used to
calculate a class mean quickly and plot a graph of these results.
Extend
Students could consider the effect of temperature on a reaction where the
particles are in a solid state. As the particles are only vibrating, not moving,
there will be no increase or decrease in frequency of collisions as temperature
is changed. However, the solids would need to be mixed for the reactant
particles to come into contact with each other. They would then need an input
of energy to overcome the activation energy.
Practical support
Reacting magnesium and hydrochloric acid at
different temperatures
Equipment and materials required
Ice bath, test tube rack, hot water bath, 1 mol/dm3 hydrochloric acid (CLEAPSS
Hazcard 47A), 1 cm magnesium strips (CLEAPSS Hazcard 59A), calcium carbonate,
two measuring cylinders, six test tubes, thermometer, eye protection.
Details
Wearing eye protection, measure out 2 cm3 of acid into each test tube, put two
test tubes in an ice bath, two in a test tube rack and two in a hot-water bath.
Allow the test tubes to rest in the water/ice baths for about 5 minutes to reach
the appropriate temperature. Students can check the temperature of the acid
using the thermometer. Add one strip of magnesium to each of the different
temperatures of acid. Allow the students to observe the reaction and comment
on the rate at different temperatures, encouraging them to decide how they are
determining the rate [amount of bubbles produced]. Keep the lab well
ventilated. Repeat the reaction with one marble chip (calcium carbonate) in
each test tube.
The effect of temperature on rate of reaction
Equipment and materials required
Two measuring cylinders, stopwatch, paper with large cross in the centre, conical
flask, 0.2 mol/dm3 sodium thiosulfate, 0.2 mol/dm3 hydrochloric acid, ice bath, water
bath/hot plate, thermometer, eye protection (chemical splashproof goggles).
Details
Measure 10 cm3 of acid (eye protection should be worn) and 10 cm 3 of sodium
thiosulfate in separate clean measuring cylinders and reduce or increase the
temperatures of these solutions using ice baths/water baths/hot plates. Choose
temperatures that are easy to attain, e.g. 10 °C, 20 °C, 30 °C, 40 °C, 50 °C
(maximum). At least five experiments need to be completed to draw a line
graph. Place the conical flask on the centre of the large cross; first add the
sodium thiosulfate to the beaker. Then add the acid and start the stopwatch
and swirl to mix the solutions. Stop the clock when the cross disappears and
note the time. You may wish to use a light sensor.
Safety: This experiment produces sulfur dioxide, which is toxic and can trigger
asthmatic attacks. Therefore this practical should be completed in a wellventilated room. Once the reaction is complete, follow CLEAPSS guidelines in
Hazcard 95C for correct disposal.
Text © Ruth Miller, Geoff Carr, Darren Forbes, Sam Holyman 2011
Course
Subject
Topic
Pages
Additional
science
Chemistry
C2 4.4 The effect of
concentration or pressure
Pages 132–133
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn that:
 that increasing the
concentration of reactants
in solutions increases the
rate of reaction
 that changing the pressure
of reacting gases changes
the rate of reaction.
Most students should be able to:
 state what effect increasing the
concentration of reactants in solutions
has on the rate of reaction
 describe what we mean by gas
pressure
 state what effect increasing the
pressure of reacting gases has on the
rate of reaction.
Some students should also be able to:
 explain in detail the effect of changing
concentration on the rate in terms of
collision theory
 explain in detail the effect of changing
pressure on the rate in terms of
collision theory.
Increasing the pressure of reacting
gases increases the frequency of
collisions and so increases the rate of
reaction. [C2.4.1 d)]
Increasing the concentration of reactants
in solutions increases the frequency of
collisions and so increases the rate of
reaction. [C2.4.1 e)]
Interpret graphs showing the amount of
product formed (or reactant used up)
with time, in terms of the rate of the
reaction.
Controlled Assessment: AS4.3 Collect
primary and secondary data. [AS4.3.2
a)]; AS4.5 Analyse and interpret primary
and secondary data. [AS4.5.3 a),
AS4.5.4 a)]
Simulation: How can I
change the rate of a
reaction?
Data handling skills:
Effect of concentration on
reaction rate
Support: Changing the
rate
Bump up your grade:
Changing the rate
Practical: The effect of
concentration on reaction
rates
How Science Works: The
state of the rates
Lesson structure
Support, Extend and Practical notes
Starters
Graph – Give students an unfinished concentration–time graph with two curved lines
to show reactants and products. Ask students to complete the axis labels (including
units) and briefly explain the shape of the two curves. Support students by giving them
the missing labels to add to the graph. Extend students by asking them to plot a few
additional data points and draw a line of best fit. (5 minutes)
Demonstration – Show the students a bottle of undiluted squash. Then put half into a
large beaker and add water. Ask the students which container has the most
concentrated drink and how they know. Then ask the students to work in pairs to come
up with a definition of concentration. Ask each pair to come to the board and write
down their definition. Ask the whole class to consider the definitions and decide on the
best. (10 minutes)
Main
Students can experimentally determine the effect of concentration on rate by observing
the reaction between marble chips and acid. At this point, moles have been introduced
to students but not calculations in terms of moles per unit volume. Therefore, to
change the concentration, the volume of the acid should be diluted with water but the
volume of the mixture should remain constant, so that the experiment is fair.
Encourage the students to plot all the curves on the same axis. Then ask students to
explain their results using collision theory. (This offers another excellent opportunity to
cover any investigative aspect of the Controlled Assessment.)
Give students an A4 sheet of paper and ask them to split in it half. On one side they
should explain how concentration affects rate and on the other how pressure affects
rate. In each section they should define the key word (concentration/pressure) and
include one labelled diagram. Ensure that students do not put their name on the front
of the poster. (See Plenary on ‘Exhibition’.)
Plenaries
Exhibition – Get all the students’ posters from the main part of the lesson. Lay them
out on the side benches and give each a number. Arrange students in small groups
and ask them to rate each poster out of 10 in terms of presentation, accuracy of
science and ease of understanding. (5 minutes)
Demonstration – For this demonstration, iron wool, tongs, deflagration spoon, a gas
jar of oxygen and a Bunsen burner and safety equipment is needed. Using a safety
screen between the class and the demonstration (plus eye protection), hold some iron
wool into a blue Bunsen flame using tongs. Then put some iron wool on a deflagration
spoon and heat it until it is glowing in the top of a blue gas cone. Then quickly put the
wool into a gas jar of oxygen. Ask students, in small groups, to explain which reaction
was more vigorous and why. Then choose a few students to feedback into the class.
(10 minutes)
Support
Students often find it difficult to understand what
concentration is. Get a bottle of coloured squash and
explain that there are lots of coloured particles mixed in the
water. Ask a student to draw a particle diagram of this
using blue pen for water particles and red pen for squash
particles. Then measure 50 cm3 of squash into a beaker
and add 50 cm3 of water. Ask a student to draw the new
particle model, and explain that the concentration of squash
has been halved.
Extend
Ask students to explain the effects of changing pressure on
the rate of reaction for a chemical change with gaseous
reactants [an increase in pressure increases the amount of
gaseous reactants in a given volume/ space, making
collisions more likely and rate of reaction increases]. You
could extend students further to explain the effects of
changing pressure on a chemical change that has no
reactants in the gaseous state [no change].
Practical support
Investigating the effect of concentration on
rate of reaction
Equipment and materials required
Marble chips, 1 mol/dm3 hydrochloric acid (CLEAPSS
Hazcard 47A), 250 cm3 conical flask, top-pan balance,
cotton wool, stopwatch, measuring cylinder, eye protection.
Details
Put about five marble chips into the bottom of a conical
flask. Measure out 25 cm3 of acid (wear eye protection),
and put it into the conical flask. Put a piece of cotton wool
in the neck. Quickly place it on the balance and take a
reading, start the stopwatch. Measure the mass of the
conical flask every 10 s for 2 min. You may wish to monitor
this reaction by sealing the container and using a carbon
dioxide probe or gas pressure probe and data logger.
Repeat for different concentrations.
Safety: Use a loose seal to prevent a build-up of pressure
in the glass vessel.
Text © Ruth Miller, Geoff Carr, Darren Forbes, Sam Holyman 2011
Course
Subject
Topic
Pages
Additional
science
Chemistry
C2 4.5 The effect of
catalysts
Pages 134–135
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 what a catalyst is
 how catalysts affect the
rate of reactions.
Most students should be able to:
 give a definition of a catalyst
 give an example of an industrial
process that uses a catalyst
 list the reasons why a catalyst may be
used in an industrial process.
Some students should also be able to:
 explain in detail why a catalyst would
be used in an industrial process.
Catalysts change the rate of chemical
reactions but are not used up during the
reaction. Different reactions need different
catalysts. [C2.4.1 g)]
Catalysts are important in increasing the
rates of chemical reactions used in industrial
processes to reduce costs. [C2.4.1 h)]
Controlled Assessment: AS4.4 Select and
process primary and secondary data.
[AS4.4.2 c)]
Extension: How do
catalysts work?
Practical: The effect
of catalysts reaction
rate
Lesson structure
Support, Extend and Practical notes
Starters
True or false – Give each student a statement about catalysts. Then
they must walk around the room and ask three people if they think
the statement is true or false. Based on these answers, the student
should decide whether the statement is true or false. You may wish
to ask each student to read his or her statement to the class and say
if they think it is true or false. Then you give feedback. (5 minutes)
Foam of death – Write the formula of hydrogen peroxide (H2O2) on
the board and ask the students to predict what the gaseous product
of the decomposition reaction could be and how it could be tested
[oxygen, which is tested with a glowing splint; they will often
incorrectly suggest hydrogen, which ‘pops’ with a lighted splint]. See
‘Practical support’. You could support students by using a periodic
table and asking for volunteers to suggest the elements that the
compound contains. As an extension, when the foam has dried
slightly, allow students to come up to the foam and relight a glowing
splint. Explain that the manganese(IV) oxide was not used up in the
reaction, but increased the rate and this is a catalyst. (10 minutes)
Main
Hydrogen peroxide is unstable in sunlight and will decompose into
oxygen and water. This process is relatively slow, but a number of
catalysts can be used to speed up this reaction: chopped raw potato;
chopped fresh liver; manganese(IV) oxide. Encourage students to
investigate gas production using the different catalysts to decide the
best. Students should consider the dependent, independent and
control variables. They should take a set of results for each catalyst
and draw all the lines of best fit on the same graph, giving more
coverage of the investigative aspects of the Controlled Assessment.
Encourage the students to create an eight-line poem, where the first
letters of each line spell ‘catalyst’. Then choose some students to
read their poem to the rest of the class.
Plenaries
Txt – Ask students to write a text message to summarise what they
have learnt today. You could support students by giving them the
text message and ask them to rewrite it in standard English.
Students could be extended by being asked to include an example of
a chemical reaction that can be affected by a catalyst. (5 minutes)
AfL (Assessment for Learning) – To continue ‘the poem’ activity
from the main part of the lesson, ask students to swap their poem
with a partner. If students feel that there is some incorrect science,
they should amend the work in pencil. Once they have worked on
the poem, it should be returned to its owner who should then review
any comments that have been made. (10 minutes)
Support
You could support students in drawing the graph by giving them the labelled
axis with the scales already written on to it. Encourage students to use a
different colour for each catalyst that they consider for the decomposition of
hydrogen peroxide.
Extend
Ask students to discover some other examples of chemical reactions and the
catalysts that they can use. You could also ask students to discover about
inhibitors (catalysts that are used to slow down the rate of reaction or
negative catalysts – e.g. in petrol).
Practical support
Foam of death
Equipment and materials required
Hydrogen peroxide (100 vol.) (CLEAPSS Hazcard 50 – corrosive), 1000 cm3
measuring cylinder, washing-up bowl, washing-up liquid, manganese(IV)
oxide (harmful), spatula, cobalt chloride paper, splints, eye protection and
gloves.
Details
Stand a 1000 cm3 measuring cylinder in a washing-up bowl. Add a good dash
of washing-up liquid, and about 100 cm3 of 100 vol. H2O2. Add a spatula of
manganese(IV) oxide and allow the students to observe.
Safety: Wear eye protection and be aware of skin burns. CLEAPSS Hazcard
60 Manganese(IV) oxide – harmful; 25 Cobalt chloride – toxic and harmful.
Investigating catalysis
Equipment and materials required
Stand, boss, gas syringe holder, gas syringe, 10 vol. Hydrogen peroxide
(irritant), manganese(IV) oxide (harmful), potato, liver, white tile, knife,
stopwatch, conical fl ask, bung, delivery tube, about a 25 cm length of rubber
tube, measuring cylinder, spatula, eye protection.
Details
Measure out 25 cm3 of hydrogen peroxide and put it into the conical flask,
eye protection should be worn. Finely chop some raw potato and put it into
the flask. Quickly connect the bung to the gas syringe and note the volume of
gas produced every 10 s for 2 min. Repeat with chopped liver, and repeat
with a spatula of manganese(IV) oxide. Other transition metal oxides can also
be investigated. You may wish to monitor this reaction by sealing the
container and using a carbon dioxide probe or gas pressure probe and data
logger.
Safety: Be aware of irritation caused by the hydrogen peroxide. Wash the
affected area under cold water and it should dissipate. Make sure the syringe
plunger is free moving. Make sure the seal is loose to avoid the glass
container exploding. CLEAPSS Hazcard 60 Manganese(IV) oxide – harmful.
Text © Ruth Miller, Geoff Carr, Darren Forbes, Sam Holyman 2011
Course
Subject
Topic
Pages
Additional
science
Chemistry
C2 4.6 Catalysts in action
Pages 136–137
Learning objectives
Learning outcomes
Specification link-up
Kerboodle
Students should learn:
 why catalysts are used in so
many industrial processes
 how new catalysts are
developed and the reason why
there are so many different
catalysts
 why there are disadvantages
of using catalysts in industry.
Most students should be able to:
 state some advantages and
disadvantages of using catalysts.
 explain why there are so many
catalysts.
Some students should also be able to:
 evaluate the advantages and
disadvantages of using catalysts in
industry.
Catalysts are important in increasing the
rates of chemical reactions used in industrial
processes to reduce costs. [C2.4.1 h)]
Explain and evaluate the development,
advantages and disadvantages of using
catalysts in industrial processes. [C2.4]
WebQuest:
Catalytic
nanoparticles
Lesson structure
Support, Extend and Practical notes
Starters
Enzymes – Show students a photograph of a stomach, washing powder,
washing-up liquid, and carpet cleaner. Ask students to make the link
between the pictures [they all use enzymes]. Support students by giving
them the word ‘enzyme’ as an anagram to help them get the connection.
Extend students by asking them to give a definition of an enzyme
[biological catalyst]. (5 minutes)
Catalytic converter – Get an old catalytic converter (from a scrapyard)
and have it cut into slices (maybe in the Technology Department). Clean
out the deposits, then show the slices (they look like a honeycomb) to the
students. The students should be encouraged to discuss in small groups
what this could be used for. Ask each group to feed back their thoughts
and then share with the students that it is a catalytic converter used on a
car exhaust to remove pollutant gases. (10 minutes)
Main
Most industrial reactions use catalysts to reduce production costs.
However, there are some disadvantages of using catalysts. Ask students
to draw a table of advantages and disadvantages of using transition
metals and their compounds, as well as enzymes. Extend students by
asking them to underline the environmental statements in green, social
statements in orange and economic statements in black.
Catalysts are being developed all the time. Students could use secondary
research such as books in the school library or the internet to find out
current developments in catalysts. Key words would include: zeolites,
fullerenes and nanochemistry. Students could then work in groups to
make a 3-minute presentation about what they have found out.
Plenaries
Definitions – Ask students to use the Student Book to define the
following key terms: catalyst [a chemical that changes the rate of reaction
without being used up, e.g. manganese(IV) oxide used in the
decomposition of hydrogen peroxide], enzyme [biological catalyst, e.g.
lipase], transition metals [metals found in the central block of the periodic
table and are often toxic, e.g. chromium]. Support students by giving
them the words and the definitions so that they just match them up.
Extend students by asking them to give an example for each. (5 minutes)
Press conference – Each group could give its presentation to the rest of
the class. One student from each group in the audience should then pose
a question to the presenters based on what they have seen and heard.
The group should then answer the questions. (10 minutes)
Support
Give students a flow chart with missing information to explain how new
catalysts are researched, designed and made. You may wish to give the
missing information to the students so that they can complete the activity
as a ‘cut-and-stick’ activity.
Extend
Ask students to research industrial processes and the catalysts that they
use, e.g. the contact process to make sulfuric acid, which uses
vanadium(V) oxide.
Text © Ruth Miller, Geoff Carr, Darren Forbes, Sam Holyman 2011