Year 10 Science · Unit 2 · Lesson 6
Foundation Worksheet
Learning Goals
Match each term to its definition
Draw a line connecting each term on the left to its correct definition on the right. Or write the matching letter next to each term.
| Term | Your answer | Definition |
|---|---|---|
| Synthesis reaction | A. A substance in a chemical equation that is formed by the reaction | |
| Decomposition reaction | B. A reaction that releases energy to the surroundings (usually as heat or light) | |
| Reactant | C. A chemical reaction where two or more substances combine to form one product (A + B → AB) | |
| Product | D. A representation using names of substances to show what reacts and what forms | |
| Word equation | E. A reaction where one substance breaks down into two or more simpler products (AB → A + B) | |
| Exothermic | F. A starting substance that takes part in a chemical reaction |
Sort it!
Write each reaction from the pool into the correct category box. Two of the reactions fit neither category, write those in "Neither".
Synthesis
Decomposition
Neither
1. The Haber process combines nitrogen gas and hydrogen gas to form ammonia (NH₃). Identify this as a synthesis or decomposition reaction, and write the word equation. Ammonia plants have to remove heat from the reactor to stop it overheating. Use that fact to say whether the reaction is exothermic or endothermic, and explain what it tells you about the bonds formed in ammonia compared with the bonds broken in N₂ and H₂. Do not answer from the reaction type alone.
2. In 1774, Joseph Priestley heated mercury(II) oxide and discovered oxygen. Identify this as synthesis or decomposition and write the word equation. Priestley had to keep the mercury(II) oxide hot the whole time, not just light it once. Use that observation to say whether the reaction was endothermic or exothermic, and explain what it tells you about where the energy was going.
Wrap Up
In one sentence, what was the main idea of this lesson?