AQA GCSE
Notes and Questions
Rate and extent of Chemical
Changes
Rate of Reaction:
The rate of a chemical reaction can be found by measuring the
q__________ of a r_________ used or the q__________ of a
p_________ formed over t_______.
1. Give the two equations for calculating the mean rate?
2. What quantities can we measure the chemicals in?
3. What are the units of rate?
4. a) Explain the shape of this graph?
b) Draw a tangent on the curve at 90 seconds
c) Calculate the gradient of the tangent.
Collision Theory
Collision theory explains how various factors affect rates of
reaction:
5. According to the Collision theory, chemical reactions can only
occur when?
6. What factors affect the rate of reaction?
7. In order to increase the rate of reaction we have to do
what?
8. Link the factors that affect the rate of reaction with their
reason ?
Increasing
concentration
(solution)
Increases the
frequency of collisions
and so increases the
Increasing rate of reaction
temperature
Increasing
pressure Makes the collisions
(gases) more energetic, and so
increases the rate of
reaction
Increasing
surface area
(solids)
8. Explain the following:
a) We put food in the fridge to preserve it!
b) Grain silos can explode!
c) Never through aerosols on to fires!
d)
Catalysts:
Catalysts change the r_____ of chemical reactions but are not
_____ up during the reaction. Different reactions require
d_________ c__________. E__________ acts as c________ in
b___________ systems.
C_________ i_________ the rate of reaxtion by providing an
a___________ p___________ for the reaction that has a
l________ A___________ energy.
9. Draw a reaction profile diagram for a catalysed reaction.?
Catalytic activity can be identified because there is an effect on the
rate of reaction but they are not included in the c_________
e__________ for the reaction.
Reversible Reactions and Dynamic Equilibrium
In some reactions, the p__________ of the reaction can react to
produce the original r_________. Such reactions are called
r__________ reactions.
10. How do we represent a reversible reaction.?
If a reaction is ex_________ in one direction, it must be
en__________ in the opposite direction. The same amount of
e__________ is transferred in each case.
11. Give an example of this type of reaction?
When a r________ reaction occurs in a s________ c__________,
e_________ is reached.
12. Why must the container be sealed?
13. What happens to the rate at equilibrium?
Effect of changing Conditions on Equilibrium:
The relative a_________ of all the reactants and products at
equilibrium depend on the c___________ of the reaction.
If a system is at equilibrium and a change is made to any of the
conditions, then the s_______ responds to c_________ the change.
13. How can we predict the effect of the changes?
Effect of changing Concentration on Equilibrium:
If the concentration of one of the reactants or products is changed,
the system is no longer at e_______ and the c___________ of all
the substances will change until the e____________ is reached
again.
14. If the concentration of a reactant is increased what
happens?
15. If the concentration of a product is increased what
happens?
Effect of Changing Temperature on Equilibrium:
If the t_________ of a system at equilibrium is i___________:
a) the relative amount of p________ at equilibrium
i__________ for an en__________ reaction.
b) the relative amount of p________ at equilibrium
d__________ for an ex__________ reaction.
If the t_________ of a system at equilibrium is d___________:
a) the relative amount of p________ at equilibrium
d__________ for an en__________ reaction.
b) the relative amount of p________ at equilibrium
i__________ for an ex__________ reaction.
16. To get a higher yield in a reaction what temperature should
be used?
Endothermic Low
reaction temperature
Exothermic High
reaction temperature
17. What is one of the issues with using low temperatures to
change the equilibrium conditions?
The effect of pressure change on Equilibrium:
For gaseous reactions at equilibrium:
a) an i_________ in pressure causes the equilibrium to shift
towards the side with the s_______ number of
m_________ as shown by the symbol equation for that
reaction
b) a d_________ in pressure causes the equilibrium to shift
towards the side with the l_______ number of
m_________ as shown by the symbol equation for that
reaction
18. To get a higher yield in a reaction what pressure should be
used?
A decrease High
in moles of pressure
gas
An increase Low
in moles of pressure
gas
19. What effect will pressure have if there is no change in the
moles of gas?
20. What issue is there with using high pressures for high
yields?
20. Give and explain the optimum conditions for the following
equilibrium:
21. Give and explain the optimum conditions for the following
equilibrium:
22. Give and explain the optimum conditions for the following
equilibrium:
