Rates of Reaction Worksheet - GCSE - Beginner

Rates of Reaction worksheet for GCSE (Key Stage 4 / GCSE (Ages 14-16)). Beginner level science practice, aligned to the UK National Curriculum. Print-ready with answer key included.

Science•Key Stage 4 / GCSE (Ages 14-16)•Rates of Reactionbeginner

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Rates of Reaction: Collision Theory in Action

GCSE Chemistry | Ages 14–16 | Beginner

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Instructions: Work through the activities in order. Use the collision-theory model in your explanations: particles must collide, and successful collisions need enough energy. Show working for calculations and include units where appropriate.

What Changes the Rate?

Choose the best answer for each question. Think about how each factor changes the frequency of collisions or the energy of particles.

1. Which change usually increases the rate of a reaction between two solutions?

2. Why does increasing temperature usually make a reaction faster?

3. Which change increases the surface area of a solid reactant?

4. What is the main effect of adding a catalyst?

Explain Using Collision Theory

Complete each sentence with the scientific idea that best explains the rate change. Refer to particles, collisions and activation energy where relevant.

1. A reaction happens when reactant particles have a successful collision. For a collision to be successful, particles must collide with enough energy to overcome the ___.

2. Increasing the concentration of a solution puts more particles into the same volume. This increases the number of collisions per ___ .

3. Increasing the temperature gives particles more kinetic energy. A greater proportion of collisions have energy equal to or greater than the ___ .

4. A catalyst provides an alternative reaction pathway with a lower ___ .

Compare Reaction Conditions

Use the completed results table to compare the rates. Rate is calculated as the amount of gas produced divided by the time taken. Show your working for the calculation questions.

Experiment	Condition	Time to collect 40 cm³ gas
A	Large marble chips	80 s
B	Small marble chips	40 s
C	Large marble chips at higher temperature	20 s

1. Calculate the mean rate for Experiment A in cm³/s.

2. Calculate the mean rate for Experiment B in cm³/s.

3. Which experiment shows the effect of increasing the solid's surface area?

4. State the factor changed between Experiments A and C.

Read a Rate Graph

The table gives the volume of gas collected at different times in one reaction. Use the values to describe the graph's shape and compare rates. A steeper graph means a faster rate.

Time (s)	Gas volume (cm³)
0	0
10	24
20	40
30	50
40	54

1. How much gas has been produced after 20 seconds?

2. Calculate the mean rate during the first 20 seconds in cm³/s.

3. Between which pair of recorded times is the increase in gas volume greatest?

4. Describe what happens to the rate as the reaction proceeds, using evidence from the table.

Catalysts and Rate Profiles

Answer using the information in each question and your knowledge of catalysts. Keep explanations focused on activation energy and whether the catalyst is consumed.

1. A reaction has an activation energy of 80 kJ/mol without a catalyst and 50 kJ/mol with a catalyst. By how many kJ/mol has the activation energy decreased?

2. Explain why a catalyst can increase the rate without being used up overall.

3. A student adds a catalyst to a reaction mixture. State one observation that could show the reaction is proceeding faster.

4. Explain, using collision theory, why a lower activation energy leads to more successful collisions per second.

Apply the Ideas

For each situation, identify the factor affecting rate and explain the change using collision theory. Use complete scientific sentences.

1. Magnesium powder reacts with dilute hydrochloric acid faster than the same mass of magnesium ribbon. Identify the factor and explain the rate increase.

2. A student repeats a reaction using a more concentrated acid at the same temperature. Explain why the rate is likely to increase.

3. A reaction mixture is warmed, while the amounts and concentrations of reactants stay the same. Explain why the rate increases.

Answer Key

Activity 1: 1. Higher concentration ; 2. More particles have energy at or above the activation energy ; 3. Crushing it into powder ; 4. It lowers the activation energy

Activity 2: 1. activation energy ; 2. unit of time ; 3. activation energy ; 4. activation energy

Activity 3: 1. 40 ÷ 80 = 0.5 cm³/s ; 2. 40 ÷ 40 = 1 cm³/s ; 3. Experiments A and B ; 4. Temperature

Activity 4: 1. 40 cm³ ; 2. 40 ÷ 20 = 2 cm³/s ; 3. 0–10 seconds ; 4. The rate decreases as the reaction proceeds: the volume increases by 24 cm³ in the first 10 seconds, then by 16, 10 and 4 cm³ in successive 10-second intervals.

Activity 5: 1. 30 kJ/mol ; 2. A catalyst provides an alternative pathway with lower activation energy and is regenerated/not used up overall ; 3. For example, gas is produced more quickly or the same volume of gas is produced in less time ; 4. More particles have energy equal to or greater than the lower activation energy, so a greater proportion of collisions are successful per second.

Activity 6: 1. Surface area; powder exposes more magnesium particles, increasing collision frequency with acid particles ; 2. Concentration; more acid particles are present per unit volume, so collisions with magnesium occur more often ; 3. Temperature; particles have more kinetic energy and move faster, and a greater proportion of collisions have energy at or above the activation energy.