AQA GCSE CHEMISTRY 8462/1H
HIGHER TIER PAPER 1 EXAM
QUESTIONS AND ANSWERS. VERIFIED
2026.
How do you measure the rate of a reaction? - ANS By measuring the quantity of a reactant
used or the quantity of product formed over time
What is the equation for calculating the mean rate of a reaction by measuring the amount of
reactant used? - ANS Mean rate of reaction = quantity of reactant used/time taken
What is the equation for calculating the mean rate of a reaction by measuring the amount of
product formed? - ANS Mean rate of reaction = quantity of product formed/time taken
What units can you measure the rate of a reaction in? - ANS g/s or cm3/s or mol/s
How do you calculate the rate of a reaction at a specific time from graph of the quantity of
reactant used or the quantity of product formed? - ANS By measuring the gradient of a
tangent drawn at that specific time on the graph
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,What are the five factors that can affect the rate of a reaction? - ANS Concentration of
reactants in solution, pressure of reacting gases, surface area of solid reactants, temperature
and the presence of a catalyst
What theory can we use to explain how various factors affect the rate of a reaction? -
ANS Collision theory
What is collision theory? - ANS Chemical reactions can occur only when reacting particles
collide with each other and with sufficient energy
What is the activation energy of a reaction? - ANS The minimum amount of energy that
particles must have to react
According to collision theory why does increasing concentration of reactant in solution increase
the rate of the reaction? - ANS It increases the frequency of collisions and so increases the
rate of reaction
According to collision theory why does increasing the pressure of reacting gases increase the
rate of the reaction? - ANS It increases the frequency of collisions and so increases the rate of
reaction
According to collision theory why does increasing the surface area of solid reactants in solution
increase the rate of the reaction? - ANS It increases the frequency of collisions and so
increases the rate of reaction
According to collision theory why does increasing temperature increase the rate of the
reaction? - ANS It increases the frequency of collisions and makes the collision more
energetic and so increases the rate of reaction
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,How do you increase the surface area of a solid reactant? - ANS Grind it into a powder that
has smaller particle size
What effect does increasing the temperature of a reaction by 10°C have on the rate of a
reaction? - ANS It doubles it
What is a catalyst? - ANS A chemical that changes the rate of a chemical reaction but is not
used up in the reaction
How do catalysts increase the rate of a reaction? - ANS By providing a different pathway for
the reaction that has a lower activation energy
How do you know in a reaction that a chemical is used in a reaction is a catalyst? - ANS It is
not included in the chemical equation for the reaction
What is a reversible reaction? - ANS Where the products of a chemical reaction can react to
produce the original reactants
What is the symbol used in reversible reaction equations that shows that the reaction is
reversible? - ANS
How can you change the direction of a reversible reaction? - ANS By changing the conditions;
for example heating or cooling the reaction
Describe the energy changes in a reversible reaction - ANS One direction will be exothermic
and the other direction endothermic
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, When is equilibrium in a reversible reaction achieved in apparatus which prevents the escape of
reactants and products? - ANS When the rate of the forward and reverse reactions occur at
exactly the same rate
What affects the relative amount of all the reactants and products at equilibrium in a reversible
reaction? - ANS The conditions
What happens to an equilibrium if any of the conditions change? - ANS The system responds
to counteract the change
What does Le Chatelier's principle predict? - ANS The effects of changing conditions on a
system at equilibrium
What affect will changing the concentration of one of the reactants in a reversible reaction have
on the equilibrium? - ANS The system will no longer be in equilibrium and the concentration
of all the substances will change until equilibrium is reached again
What happens when the concentration of a reactant is increased in a reversible reaction? -
ANS More products will be formed until equilibrium is reached again
What happens when the concentration of a product is decreased in a reversible reaction? -
ANS More reactant will react until equilibrium is reached again
What happens when the temperature of a system in equilibrium is increased? - ANS The
relative amount of products at equilibrium increases for an endothermic reaction OR The
relative amount of products at equilibrium decreases for an exothermic reaction
4 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
HIGHER TIER PAPER 1 EXAM
QUESTIONS AND ANSWERS. VERIFIED
2026.
How do you measure the rate of a reaction? - ANS By measuring the quantity of a reactant
used or the quantity of product formed over time
What is the equation for calculating the mean rate of a reaction by measuring the amount of
reactant used? - ANS Mean rate of reaction = quantity of reactant used/time taken
What is the equation for calculating the mean rate of a reaction by measuring the amount of
product formed? - ANS Mean rate of reaction = quantity of product formed/time taken
What units can you measure the rate of a reaction in? - ANS g/s or cm3/s or mol/s
How do you calculate the rate of a reaction at a specific time from graph of the quantity of
reactant used or the quantity of product formed? - ANS By measuring the gradient of a
tangent drawn at that specific time on the graph
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,What are the five factors that can affect the rate of a reaction? - ANS Concentration of
reactants in solution, pressure of reacting gases, surface area of solid reactants, temperature
and the presence of a catalyst
What theory can we use to explain how various factors affect the rate of a reaction? -
ANS Collision theory
What is collision theory? - ANS Chemical reactions can occur only when reacting particles
collide with each other and with sufficient energy
What is the activation energy of a reaction? - ANS The minimum amount of energy that
particles must have to react
According to collision theory why does increasing concentration of reactant in solution increase
the rate of the reaction? - ANS It increases the frequency of collisions and so increases the
rate of reaction
According to collision theory why does increasing the pressure of reacting gases increase the
rate of the reaction? - ANS It increases the frequency of collisions and so increases the rate of
reaction
According to collision theory why does increasing the surface area of solid reactants in solution
increase the rate of the reaction? - ANS It increases the frequency of collisions and so
increases the rate of reaction
According to collision theory why does increasing temperature increase the rate of the
reaction? - ANS It increases the frequency of collisions and makes the collision more
energetic and so increases the rate of reaction
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,How do you increase the surface area of a solid reactant? - ANS Grind it into a powder that
has smaller particle size
What effect does increasing the temperature of a reaction by 10°C have on the rate of a
reaction? - ANS It doubles it
What is a catalyst? - ANS A chemical that changes the rate of a chemical reaction but is not
used up in the reaction
How do catalysts increase the rate of a reaction? - ANS By providing a different pathway for
the reaction that has a lower activation energy
How do you know in a reaction that a chemical is used in a reaction is a catalyst? - ANS It is
not included in the chemical equation for the reaction
What is a reversible reaction? - ANS Where the products of a chemical reaction can react to
produce the original reactants
What is the symbol used in reversible reaction equations that shows that the reaction is
reversible? - ANS
How can you change the direction of a reversible reaction? - ANS By changing the conditions;
for example heating or cooling the reaction
Describe the energy changes in a reversible reaction - ANS One direction will be exothermic
and the other direction endothermic
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, When is equilibrium in a reversible reaction achieved in apparatus which prevents the escape of
reactants and products? - ANS When the rate of the forward and reverse reactions occur at
exactly the same rate
What affects the relative amount of all the reactants and products at equilibrium in a reversible
reaction? - ANS The conditions
What happens to an equilibrium if any of the conditions change? - ANS The system responds
to counteract the change
What does Le Chatelier's principle predict? - ANS The effects of changing conditions on a
system at equilibrium
What affect will changing the concentration of one of the reactants in a reversible reaction have
on the equilibrium? - ANS The system will no longer be in equilibrium and the concentration
of all the substances will change until equilibrium is reached again
What happens when the concentration of a reactant is increased in a reversible reaction? -
ANS More products will be formed until equilibrium is reached again
What happens when the concentration of a product is decreased in a reversible reaction? -
ANS More reactant will react until equilibrium is reached again
What happens when the temperature of a system in equilibrium is increased? - ANS The
relative amount of products at equilibrium increases for an endothermic reaction OR The
relative amount of products at equilibrium decreases for an exothermic reaction
4 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
