CHEMISTRY A HIGHER TIER ALL ASSESSMENT
FINAL PRACTICE SET 2026 QUESTIONS AND
ANSWERS
◉ What is the equation for calculating the mean rate of a reaction by
measuring the amount of reactant used? Answer: 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? Answer: Mean rate of
reaction = quantity of product formed/time taken
◉ What units can you measure the rate of a reaction in? Answer: 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? Answer: By measuring the gradient of a tangent drawn at
that specific time on the graph
◉ What are the five factors that can affect the rate of a reaction?
Answer: 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? Answer: Collision theory
◉ What is collision theory? Answer: Chemical reactions can occur
only when reacting particles collide with each other and with
sufficient energy
◉ What is the activation energy of a reaction? Answer: 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? Answer: 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? Answer: 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?
Answer: 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? Answer: It increases the frequency
of collisions and makes the collision more energetic and so increases
the rate of reaction
◉ How do you increase the surface area of a solid reactant? Answer:
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? Answer: It doubles it
◉ What is a catalyst? Answer: 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? Answer: 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? Answer: It is not included in the chemical
equation for the reaction
◉ What is a reversible reaction? Answer: 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? Answer:
◉ How can you change the direction of a reversible reaction?
Answer: By changing the conditions; for example heating or cooling
the reaction
◉ Describe the energy changes in a reversible reaction Answer: One
direction will be exothermic and the other direction endothermic
◉ When is equilibrium in a reversible reaction achieved in
apparatus which prevents the escape of reactants and products?
Answer: 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? Answer: The conditions
◉ What happens to an equilibrium if any of the conditions change?
Answer: The system responds to counteract the change
◉ What does Le Chatelier's principle predict? Answer: The effects of
changing conditions on a system at equilibrium
FINAL PRACTICE SET 2026 QUESTIONS AND
ANSWERS
◉ What is the equation for calculating the mean rate of a reaction by
measuring the amount of reactant used? Answer: 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? Answer: Mean rate of
reaction = quantity of product formed/time taken
◉ What units can you measure the rate of a reaction in? Answer: 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? Answer: By measuring the gradient of a tangent drawn at
that specific time on the graph
◉ What are the five factors that can affect the rate of a reaction?
Answer: 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? Answer: Collision theory
◉ What is collision theory? Answer: Chemical reactions can occur
only when reacting particles collide with each other and with
sufficient energy
◉ What is the activation energy of a reaction? Answer: 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? Answer: 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? Answer: 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?
Answer: 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? Answer: It increases the frequency
of collisions and makes the collision more energetic and so increases
the rate of reaction
◉ How do you increase the surface area of a solid reactant? Answer:
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? Answer: It doubles it
◉ What is a catalyst? Answer: 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? Answer: 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? Answer: It is not included in the chemical
equation for the reaction
◉ What is a reversible reaction? Answer: 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? Answer:
◉ How can you change the direction of a reversible reaction?
Answer: By changing the conditions; for example heating or cooling
the reaction
◉ Describe the energy changes in a reversible reaction Answer: One
direction will be exothermic and the other direction endothermic
◉ When is equilibrium in a reversible reaction achieved in
apparatus which prevents the escape of reactants and products?
Answer: 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? Answer: The conditions
◉ What happens to an equilibrium if any of the conditions change?
Answer: The system responds to counteract the change
◉ What does Le Chatelier's principle predict? Answer: The effects of
changing conditions on a system at equilibrium
