Chapter 20: Rates of reaction
Reactions
1. Use the words in the box to complete the gaps below. Use each word only once.
Missing words: activation, collide, concentration, decreases, energy, measured, pressure, product,
rate, speed, surface, time
The rate of a reaction can be measured by the ____________ at which the amount of a
reactant ______________ or the amount of a ________________ increases. The amount of
substance can be _______________ by a change in volume, mass or ______________. To
calculate the ______________ of reaction we must know the change in amount of substance
and the ______________ taken. For a reaction to take place the reactants must
________________ with enough _________________ for the reaction to take place. The
amount of energy needed for a reaction to take place is called the _________________
energy. The factors that can affect the rate of a reaction are: temperature, concentration,
_____________ area, ______________ and the presence of a catalyst.
Factors that affect rate of reaction
2. Draw a line between the factors that can increase the rate of reaction and the explanation
for how each works.
Factor How it affects rate of
reaction
Surface area More particles and so more
collisions will take place
Temperature More collisions take place
in a shorter period
Pressure Alternate route for reaction
with a lower activation
energy
Concentration More kinetic energy so
particles will collide more
and with greater force
Catalyst More collisions as there are
more particles available to
react on the surface
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3. Chris and Noshaba were testing different metal oxides to investigate the effect they had
on the rate of hydrogen peroxide decomposition. In a clean conical flask they poured
50cm3 of hydrogen peroxide and added 1g of metal oxide each time. As soon as the metal
oxide was added they sealed the conical flask. They used a gas syringe to measure the
volume of oxygen produced in 5 minutes. Their results are below.
Metal oxide Volume of oxygen
produced / cm3
Manganese(IV 44.5
) oxide
Copper(II) 4.7
oxide
Aluminium(III) 3.6
oxide
Control 0.5
a. List the factors that Chris and Noshaba would have had to control to ensure a fair test.
b. (i) Why did they also have a control experiment?
(ii) What would the control experiment have been for this investigation?
c. Calculate the rate of reaction for
(i) Manganese(IV) oxide
(ii) Copper(II) oxide
(iii) Aluminium(II) oxide
(iv) Control
d. How could they have improved their experiment to get more reliable data?
e. Chris and Noshaba filtered out the metal oxides at the end of the experiment. They
allowed them to dry. Suggest what the mass of each oxide would be.
4. In the space below sketch a labelled diagram of their experimental apparatus.
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5. Reactions involving catalysts can be illustrated using energy level diagrams. Add the labels
below to the diagram.
Reactants Products Progress of reaction Energy Activation energy without
catalyst Activation energy with catalyst
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