AQA GCSE Chemistry The rate and extent of chemical change Practice Questions

Question 1

Which of these is a correct unit for the rate of a chemical reaction when measuring a gas produced over time?

Accepted Answer

cm3/s. Rate is the change in amount of reactant or product divided by time, so a volume of gas over time gives units such as cm3/s.

Question 2

Increasing the temperature of a reaction usually increases the rate because the particles:

Accepted Answer

move faster and collide more frequently with more energy. Higher temperature gives particles more kinetic energy, so they move faster and collide more often and with more energy.

Question 3

A catalyst speeds up a reaction. At the end of the reaction the catalyst is:

Accepted Answer

chemically unchanged and can be reused. A catalyst is not used up in the reaction and remains chemically unchanged at the end.

Question 4

Which change would increase the surface area of a solid reactant and so increase the rate of reaction?

Accepted Answer

grinding a lump into a fine powder. Breaking a solid into a powder increases its surface area, exposing more particles to collisions.

Question 5

For a reaction to happen, collision theory states that particles must collide with enough energy. This minimum energy is called the:

Accepted Answer

activation energy. The activation energy is the minimum energy that colliding particles must have for a reaction to occur.

Question 6

In a reversible reaction, the forward and backward reactions are shown using the symbol _____ instead of a single arrow.

Accepted Answer

/ double arrow. A reversible reaction is written with a double arrow () to show it can go in both directions.

Question 7

In a reaction between marble chips and acid, the gas given off is collected. The graph of volume against time is steepest at the start and then levels off. The line levels off because:

Accepted Answer

a reactant has been used up and the reaction has stopped. The rate falls as reactants are used up; the line becomes flat when a reactant runs out and the reaction stops.

Question 8

Increasing the concentration of a dissolved reactant increases the rate of reaction because there are:

Accepted Answer

more particles in a given volume, so more frequent collisions. Higher concentration means more particles in the same volume, so collisions are more frequent.

Question 9

For a gas-phase reaction, increasing the pressure increases the rate. This is most like increasing which factor for a solution?

Accepted Answer

concentration. Increasing pressure on a gas squeezes the same number of particles into a smaller volume, which is equivalent to increasing concentration.

Question 10

A reaction produces 48 cm3 of gas in 24 seconds. What is the mean rate of reaction over this time?

Accepted Answer

2 cm3/s. Mean rate = total quantity / total time = 48 cm3 / 24 s = 2 cm3/s.

AQA GCSE Chemistry: The rate and extent of chemical change — Practice Questions & Answers

Practice questions with answers

Ready to test yourself?

Key terms in The rate and extent of chemical change

Practise other AQA GCSE Chemistry topics