Rate of reaction Formative

1. Which of the following will NOT increase the rate of a reaction?

• • Increasing temperature

• • Adding a catalyst

• • Decreasing concentration

• • Increasing surface area

1. What does a catalyst do in a chemical reaction?

• • Slows it down

• • Changes the products

• • Decreases temperature

• lowers activation energy

1. if we increase the concentration of hydrochloric acid when reacting with magnesium, what will happen to the rate of hydrogen gas produced?

• • It decreases because concentration is too high

• • It stays the same as concentration doesn't affect the rate

• frequency of successful collisions increases which increases the rate

• • It stops completely

1. Which change would increase the rate of reaction between marble chips and hydrochloric acid?

• • Using larger marble chips

• • Cooling the acid

• • Using a lower concentration of acid

• • Crushing the marble chips

1. If 50 cm³ of gas is produced in 25 seconds, what is the rate of reaction?

• • 2 cm³/s

• • 0.5 cm³/s

• • 25 cm³/s

• • 75 cm³/s

1. Which formula is correct for calculating the rate of a reaction?

• • rate = change in time ÷ change in amount

• • rate = change in amount ÷ change in time

• • rate = change in amount × change in time

• • rate = change in time × change in amount

1. What does the activation energy represent in a chemical reaction?

• • The energy released

• • The minimum energy needed for reaction

• • The energy of the products

• • The amount of catalyst used

An excess of calcium carbonate reacts with dilute hydrochloric acid. The volume of

carbon dioxide produced is measured at regular time intervals. The results are shown as experiment 1.

The experiment is repeated with only one change to the reaction conditions.

The results are shown as experiment 2.

Which change is made in experiment 2?

• The concentration of the acid is increased.

• The volume of acid is increased.

• The mass of calcium carbonate is increased.

• The calcium carbonate is powdered.

Four statements about the effect of increasing temperature on a reaction are shown.

1 The activation energy becomes lower.

2 The particles move faster.

3 There are more collisions between reacting particles per second.

4 There are more collisions which have energy greater than the activation energy.

Which statements are correct?

• 1, 2 and 3

• 1, 3 and 4

• 2, 3 and 4

• 2 and 3 only

Which changes decrease the rate of reaction between magnesium and air?

1 heating the magnesium to a higher temperature

2 using a higher proportion of oxygen in the air

3 using magnesium ribbon instead of powdered magnesium

• 1, 2 and 3

• 1 only

• 2 only

• 3 only