Year 10 Science · Unit 2 · Lesson 10
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Learning Goals
Read the energy diagrams
Two energy profile diagrams are shown below, one for an exothermic reaction, one for an endothermic reaction. Study both, then answer the questions.
Diagram A, Exothermic reaction (e.g. combustion of methane)
(a) On Diagram A, Label A points to the region between the products line and the reactants line. What does this gap represent? Is energy released or absorbed overall?
(b) Label B points to the peak of the curve. What is the name given to the energy at this peak, and why must every reaction overcome it?
(c) Sketch how Diagram A would look different for an endothermic reaction. Describe the key change in one sentence.
Compare two
Complete the table to compare exothermic and endothermic reactions.
| Feature | Exothermic | Endothermic |
|---|---|---|
| Direction of energy flow | ||
| Effect on surrounding temperature | ||
| Energy of products vs reactants | ||
| Everyday Australian example | ||
| Industrial or practical application |
1. Eucalyptus oil has a very low flash point and is highly flammable. During the 2019 Blue Mountains bushfires, gum trees were observed to "explode" as volatile oils ignited. Using your knowledge of exothermic reactions and activation energy, explain what is happening chemically.
Wrap Up
In one sentence, what was the main idea of this lesson?