AQA GCSE Chemistry Paper 2 Verified Solutions
1. How can you measure the rate of a reaction?
Answer: By measuring the quantity of reactant used or product formed over time
2. What is the formula for calculating the mean rate of reaction when measuring reactant quantity?
Answer: Mean rate of reaction = quantity of reactant used / time taken
3. What is the formula for calculating the mean rate of reaction when measuring product quantity?
Answer: Mean rate of reaction = quantity of product formed / time taken
4. In what units can you measure the rate of a reaction?
Answer: Grams per second (g/s), cubic centimeters per second (cm³/s), or moles per second (mol/s)
5. How do you calculate the rate of a reaction at a specific time from a graph?
Answer: By finding the gradient of a tangent drawn at that specific time on the graph
6. What are the five factors that can affect the rate of a chemical reaction?
Answer: Concentration of reactants, pressure of reacting gases, surface area of solid reactants,
temperature, and presence of catalysts
7. What theory explains how various factors influence the rate of a chemical reaction?
Answer: Collision theory
,8. What is collision theory in simple terms?
Answer: Chemical reactions occur only when particles collide with sufficient energy and frequency
9. What is activation energy, and what role does it play in collision theory?
Answer: It's the minimum energy required for particles to react; increasing activation energy slows
down reactions, while decreasing it speeds them up
10. How do increasing concentration, pressure, surface area, and temperature affect the rate of a
reaction according to collision theory?
Answer: Increasing these factors increases the frequency and energy of collisions, thus increasing the
rate of reaction
11. How can you increase the surface area of solid reactants?
Answer: By grinding them into smaller particles or powders
12. What happens to the rate of reaction when temperature increases by 10°C?
Answer: It doubles
13. What is a catalyst, and how does it work?
Answer: A chemical that changes the rate of a reaction without being consumed; it provides an
alternative pathway with lower activation energy
14. How can you identify whether a substance is a catalyst in a reaction?
, Answer: If it's not included in the chemical equation
15. What is a reversible reaction, and how can you change its direction?
Answer: A reaction where products can re-form reactants; direction can be changed by adjusting
conditions such as temperature or concentration
Describe the energy changes in a reversible reaction ✔️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? ✔️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? ✔️The conditions
What happens to an equilibrium if any of the conditions change? ✔️The system responds to counteract
the change
What does Le Chatelier's principle predict? ✔️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? ✔️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? ✔️More
products will be formed until equilibrium is reached again
What happens when the concentration of a product is decreased in a reversible reaction? ✔️More
reactant will react until equilibrium is reached again
1. How can you measure the rate of a reaction?
Answer: By measuring the quantity of reactant used or product formed over time
2. What is the formula for calculating the mean rate of reaction when measuring reactant quantity?
Answer: Mean rate of reaction = quantity of reactant used / time taken
3. What is the formula for calculating the mean rate of reaction when measuring product quantity?
Answer: Mean rate of reaction = quantity of product formed / time taken
4. In what units can you measure the rate of a reaction?
Answer: Grams per second (g/s), cubic centimeters per second (cm³/s), or moles per second (mol/s)
5. How do you calculate the rate of a reaction at a specific time from a graph?
Answer: By finding the gradient of a tangent drawn at that specific time on the graph
6. What are the five factors that can affect the rate of a chemical reaction?
Answer: Concentration of reactants, pressure of reacting gases, surface area of solid reactants,
temperature, and presence of catalysts
7. What theory explains how various factors influence the rate of a chemical reaction?
Answer: Collision theory
,8. What is collision theory in simple terms?
Answer: Chemical reactions occur only when particles collide with sufficient energy and frequency
9. What is activation energy, and what role does it play in collision theory?
Answer: It's the minimum energy required for particles to react; increasing activation energy slows
down reactions, while decreasing it speeds them up
10. How do increasing concentration, pressure, surface area, and temperature affect the rate of a
reaction according to collision theory?
Answer: Increasing these factors increases the frequency and energy of collisions, thus increasing the
rate of reaction
11. How can you increase the surface area of solid reactants?
Answer: By grinding them into smaller particles or powders
12. What happens to the rate of reaction when temperature increases by 10°C?
Answer: It doubles
13. What is a catalyst, and how does it work?
Answer: A chemical that changes the rate of a reaction without being consumed; it provides an
alternative pathway with lower activation energy
14. How can you identify whether a substance is a catalyst in a reaction?
, Answer: If it's not included in the chemical equation
15. What is a reversible reaction, and how can you change its direction?
Answer: A reaction where products can re-form reactants; direction can be changed by adjusting
conditions such as temperature or concentration
Describe the energy changes in a reversible reaction ✔️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? ✔️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? ✔️The conditions
What happens to an equilibrium if any of the conditions change? ✔️The system responds to counteract
the change
What does Le Chatelier's principle predict? ✔️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? ✔️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? ✔️More
products will be formed until equilibrium is reached again
What happens when the concentration of a product is decreased in a reversible reaction? ✔️More
reactant will react until equilibrium is reached again
