Activation energy and net energy change are two different features of a chemical reaction, and this Grade 10 Science worksheet helps students distinguish them using energy diagrams, reaction observations and evidence. Students investigate how energy is transferred when chemical bonds break and form, why some reactions warm their surroundings while others cool them, and how scientists can collect reliable evidence about these changes.

Read and interpret reaction energy

The reading passage introduces the energy changes that occur as atoms rearrange during chemical reactions. Students examine why breaking bonds requires energy, while forming new bonds releases energy, and why the overall result depends on the balance between these processes. The passage connects this idea to exothermic reactions, which transfer energy to the surroundings, and endothermic reactions, which take in energy from the surroundings.

Energy diagrams are a central part of the topic. Students consider reaction progress on the horizontal axis and energy on the vertical axis, then distinguish the activation energy needed to reach the peak from the net energy change between reactants and products. They also interpret what different peak heights mean when two reactions have the same starting and ending energy levels.

Apply the concepts to observations and investigations

Multiple-choice questions and true-or-false statements address activation energy, bond energy, exothermic and endothermic changes, energy diagrams and evidence from temperature observations. Short-answer work asks students to explain the difference between activation energy and net energy change, calculate the net energy change from energy absorbed and released during bond changes, and classify the reaction. Students also plan an investigation, developing a hypothesis, identifying controlled variables, choosing measurements and considering uncertainty.

The resource extends beyond interpreting reaction diagrams. Students consider repeated trials, reliable evidence, credible secondary sources and the evaluation of energy-related technology. The reading also introduces the importance of considering ethical, cultural and environmental implications when communicating about innovations, with First Peoples perspectives requiring accurate attribution and locally appropriate sources.

Files and teacher support

• Printable Grade 10 Science worksheet on energy changes and activation energy
• Separate PDF answer key for checking student responses
• Student Notes lines at the bottom of the worksheet
• Teacher Guide inside the Answer Key PDF, including Learning Objectives, Teaching Tips, Discussion Questions and Common Mistakes

Where it fits in a chemical reactions unit

Use this chemical reactions worksheet after introducing bond energy and reaction energy, or as practice when students begin interpreting energy diagrams. The investigation-planning prompt gives students an opportunity to apply scientific inquiry to temperature change, while the calculation provides a concrete way to connect energy absorbed during bond breaking with energy released during bond formation. The separate answer key and teacher guidance make it easier to check reasoning and prepare follow-up discussion.

Created for Grade 10 Science and identified with the BC framework, this resource focuses on the relationship between chemical bonds, activation energy and the overall energy change of a reaction. No specific BC curriculum code is supplied.