Chemical Reactions Worksheet — KS3 — Intermediate
Chemical Reactions worksheet for Key Stage 3 / Year 7-9 (Ages 11-14). Intermediate level science practice, aligned to the UK National Curriculum. Print-ready with answer key included.
Exploring Chemical Reactions
Key Stage 3 / Year 7-9 (Ages 11-14) - Intermediate Level
Instructions: This worksheet will guide you through various aspects of chemical reactions. You will explore reaction types, balance equations, and identify reaction products. Complete each activity carefully, using your knowledge of chemistry.
Types of Chemical Reactions
Identify the type of chemical reaction for each equation below. Use your understanding of synthesis, decomposition, single replacement, and double replacement reactions.
1. 2H₂ + O₂ → 2H₂O
2. CaCO₃ → CaO + CO₂
3. Zn + 2HCl → ZnCl₂ + H₂
4. NaOH + HCl → NaCl + H₂O
Balancing Chemical Equations
Balance the following chemical equations. Write the balanced equation in the space provided.
1. _ H₂ + _ O₂ → _ H₂O
2. _ Al + _ O₂ → _ Al₂O₃
3. _ C₃H₈ + _ O₂ → _ CO₂ + _ H₂O
4. _ Fe + _ O₂ → _ Fe₂O₃
Identifying Reaction Products
For each reactant pair, predict the products of the chemical reaction and write the balanced equation.
1. Na + Cl₂ →
2. H₂SO₄ + NaOH →
3. Mg + O₂ →
4. KBr + AgNO₃ →
Reaction Rate Factors
List three factors that can affect the rate of a chemical reaction. Provide examples for each factor.
1.
2.
3.
Exothermic and Endothermic Reactions
Classify each reaction as exothermic or endothermic. Explain your reasoning for each classification.
1. Combustion of methane: CH₄ + 2O₂ → CO₂ + 2H₂O
2. Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
3. Dissolving ammonium nitrate in water
Practical Application: Reaction Observation
Design a simple experiment to observe a chemical reaction. Identify the reactants, procedure, and expected observations.
Reactants:
Procedure:
Expected Observations:
Energy Changes in Reactions
Describe the energy changes that occur during a chemical reaction. Include examples of both endothermic and exothermic reactions.
Energy Changes:
Chemical Reaction Vocabulary
Match the following terms with their correct definitions: reactants, products, activation energy, catalyst.
1. Substances that start a chemical reaction.
2. Substances formed as a result of a chemical reaction.
3. The minimum energy required to start a reaction.
4. A substance that speeds up a reaction without being consumed.
Activity 1: Synthesis ; Decomposition ; Single Replacement ; Double Replacement
Activity 2: 2 ; 1 ; 2 ; 4 ; 3 ; 5 ; 2 ; 3 ; 2 ; 3 ; 4 ; 2 ; 4 ; 3 ; 2
Activity 3: 2NaCl ; Na₂SO₄ + H₂O ; 2MgO ; AgBr + KNO₃
Activity 4: Concentration ; Temperature ; Surface Area
Activity 5: Exothermic ; Endothermic ; Endothermic
Activity 6: Open-ended (depends on student design)
Activity 7: Open-ended (examples include combustion and photosynthesis)
Activity 8: Reactants ; Products ; Activation energy ; Catalyst
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