Year 9 Chemical Reactions Worksheet - Beginner

Year 9 Chemical Reactions worksheet for Year 9 (Key Stage 3 / Year 7-9 (Ages 11-14)). Beginner level science practice, aligned to the UK National Curriculum. Print-ready with answer key included.

Science•Key Stage 3 / Year 7-9 (Ages 11-14)•Chemical Reactionsbeginner

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Chemical Reactions: A Year 9 Guide

Key Stage 3 • Ages 13–14 • Beginner

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Instructions: Work through the activities in order, using the guidance and examples to help you. Show working where you calculate, and use the particle and atom counts in each equation carefully. Write each answer in its box.

Word and Symbol Equations

A word equation names the reactants on the left and the products on the right. In a symbol equation, use the formulae given and balance the number of each type of atom on both sides. For example, hydrogen + oxygen → water becomes 2H₂ + O₂ → 2H₂O.

1. Write a word equation for magnesium reacting with oxygen to make magnesium oxide.

2. Write a word equation for calcium carbonate breaking down into calcium oxide and carbon dioxide.

3. Balance this symbol equation: __ Mg + __ O₂ → __ MgO.

4. Balance this symbol equation: __ H₂ + __ Cl₂ → __ HCl.

Conservation of Mass

In a chemical reaction, atoms are rearranged rather than created or destroyed. In a closed system, the total mass of the reactants equals the total mass of the products. Calculate each missing value and include the unit where it is given.

1. In a sealed flask, 12 g of carbon reacts completely with 32 g of oxygen. What mass of carbon dioxide forms?

2. A reaction produces 18 g of product. One reactant has a mass of 5 g. What is the mass of the other reactant?

3. A metal gains 4 g in mass when it reacts with oxygen. Explain where the extra mass comes from.

4. A reaction in an open container appears to lose 7 g of mass. The product is a gas that escapes. What would the measured mass change be if the reaction took place in a sealed container?

Reaction Types

Combustion is a reaction with oxygen that releases energy. Oxidation is a reaction in which a substance gains oxygen. Thermal decomposition happens when heat breaks one compound into simpler substances. Identify the reaction type and complete the equations where asked.

1. Magnesium reacts with oxygen to form magnesium oxide. Name the reaction type.

2. Complete the word equation for the thermal decomposition of calcium carbonate: calcium carbonate → ___ + ___.

3. A fuel burns in oxygen and releases heat and light. Is this combustion, oxidation or thermal decomposition?

4. Copper reacts with oxygen to form copper oxide. What has happened to the copper in terms of oxygen?

Energy Changes

An exothermic reaction transfers energy to the surroundings, so the surroundings usually warm up. An endothermic reaction takes in energy from the surroundings, so the surroundings usually cool down. Classify each situation and use the temperature change as evidence.

1. A reaction makes the thermometer reading rise from 20°C to 35°C. Is it exothermic or endothermic?

2. A reaction makes the thermometer reading fall from 22°C to 16°C. Is it exothermic or endothermic?

3. In an exothermic reaction, does energy move overall into or out of the reacting chemicals?

4. A student says, “The temperature fell, so the reaction released energy to the surroundings.” Is the student correct? Give a brief reason.

Reactivity and Displacement

Use this simplified reactivity series: magnesium > zinc > iron > copper. A more reactive metal can displace a less reactive metal from its compound in solution. If the solid metal is less reactive than the metal in the compound, no displacement occurs.

1. Will magnesium displace copper from copper sulfate solution? Write yes or no and name the metal formed.

2. Will copper displace zinc from zinc sulfate solution? Write yes or no.

3. Complete the word equation: iron + copper sulfate → ___ + ___.

4. Which is more reactive, zinc or iron?

Answer Key

Activity 1: 1. magnesium + oxygen → magnesium oxide ; 2. calcium carbonate → calcium oxide + carbon dioxide ; 3. 2 Mg + O₂ → 2 MgO ; 4. H₂ + Cl₂ → 2 HCl

Activity 2: 1. 44 g ; 2. 13 g ; 3. The metal has combined with oxygen from the air, adding the oxygen’s mass ; 4. No measured mass would be lost; the total mass would remain the same because the gas stays in the sealed container

Activity 3: 1. Oxidation (also combustion when magnesium burns in oxygen) ; 2. calcium oxide + carbon dioxide ; 3. Combustion ; 4. The copper has gained oxygen (it has been oxidised)

Activity 4: 1. Exothermic ; 2. Endothermic ; 3. Out of the reacting chemicals and into the surroundings ; 4. No. A falling temperature shows that the reaction took in energy from the surroundings, so it is endothermic

Activity 5: 1. Yes; copper ; 2. No ; 3. iron sulfate + copper ; 4. Zinc