GCSE Foundation Chemistry: Reactivity, Redox & Synthesis

Master GCSE Chemistry with this guide on the reactivity series, redox reactions, extraction of metals, and salt synthesis methods for Edexcel Foundation.

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GCSE Foundation Chemistry

Reactivity Series | Redox Reactions | Synthesis

Edexcel | 2 Hour Lesson

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Lesson Overview

Part 1: Reactivity Series

• The reactivity series order
• Displacement reactions
• Reactions with water & acids
• Extracting metals

Part 2: Redox Reactions

• Oxidation & reduction
• OIL RIG mnemonic
• Electron transfer
• Identifying redox reactions

Part 3: Synthesis

• Making salts
• Neutralisation reactions
• Salt preparation methods
• Core practical

⏱ 2 Hour Lesson | Edexcel GCSE Foundation Chemistry

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Part 1 Reactivity Series

Ordering metals, displacement reactions & extracting metals from ores

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The Reactivity Series

DECREASING REACTIVITY

1. Potassium (K) - most reactive

🔵

2. Sodium (Na)

🔵

3. Lithium (Li)

🔵

4. Calcium (Ca)

🔵

5. Magnesium (Mg)

🟡

6. Aluminium (Al)

🟡

7. Zinc (Zn)

🟡

8. Iron (Fe)

🟡

9. Tin (Sn)

🔴

10. Lead (Pb)

🔴

11. HYDROGEN (H)

non-metal

12. Copper (Cu)

⚫

13. Silver (Ag)

⚫

14. Gold (Au) - least reactive

⚫

Reaction Key

🔵 React with cold water

🟡 React with steam only

🔴 React with dilute acid

⚫ Very unreactive

💡

Mnemonic

"Please Send Little Cats Meowing About Zebras In The Lovely Calm Seas Going"

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Reactions with Water and Acids

Reactions with Water

Metal	Reaction	Observation
Potassium	Reacts violently with cold water	Floats, fizzes vigorously, purple flame
Sodium	Reacts quickly with cold water	Floats, fizzes, melts into a ball
Magnesium	Reacts slowly with steam	Few bubbles
Copper	No reaction	No change

Chemical Equation

                    2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)
                

Reactions with Dilute Acids

Metal	Reaction
Magnesium	Vigorous fizzing, dissolves quickly
Zinc	Moderate fizzing
Iron	Slow fizzing
Copper	No reaction

Chemical Equation

                    Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)
                

Key

The gas produced is always HYDROGEN — tested with a lit splint (squeaky pop!)

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Displacement Reactions

A MORE reactive metal will DISPLACE a LESS reactive metal from its salt solution.

✅ Reaction Occurs

Zn + CuSO₄ → ZnSO₄ + Cu

Observation:
Blue solution goes colourless, orange/red copper metal forms

✅ Reaction Occurs

Fe + CuSO₄ → FeSO₄ + Cu

Observation:
Blue solution fades, copper deposits on iron

❌ No Reaction

Cu + ZnSO₄ → No reaction

Observation:
No change — copper is LESS reactive than zinc

💡

Remember

More reactive = pushes the less reactive metal OUT of its compound.

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Extracting Metals from Ores

How a metal is extracted depends on its position in the reactivity series.

Very Reactive Metals

Potassium, Sodium, Lithium, Calcium, Magnesium, Aluminium

Method ELECTROLYSIS

Too reactive to be reduced by carbon. Requires large amounts of electricity.

Moderately Reactive Metals

Zinc, Iron, Tin, Lead

Method REDUCTION WITH CARBON

ZnO + C → Zn + CO₂

Carbon is more reactive than these metals so it displaces them.

Unreactive Metals

Copper, Silver, Gold

Method FOUND NATIVE or SIMPLE HEATING

So unreactive they exist as pure metals in the ground.

⚠

Aluminium is extracted by electrolysis despite being common — its oxide is very stable.

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📝 EXAM QUESTIONS — Reactivity Series

Question 1

2 marks

Place the following metals in order of reactivity, starting with the most reactive: Copper, Magnesium, Zinc, Gold

Question 2

3 marks

Iron is added to copper sulfate solution. Describe what you would observe and explain why this reaction occurs.

Question 3

4 marks

A student investigates the reactions of four metals (A, B, C, D) with dilute hydrochloric acid. Metal A fizzes vigorously, metal B fizzes slowly, metal C shows no reaction, and metal D reacts explosively.

(a)

Place metals A, B, C, D in order of reactivity, most reactive first. [2 marks]

(b)

Predict what would happen if metal A was added to a solution of metal B sulfate. [2 marks]

Question 4

2 marks

Explain why gold is found as a pure metal in the ground, whereas aluminium is not.

⏱ Suggested time: 10 minutes | Put your pen down when done!

ATTEMPT THESE BEFORE LOOKING AT THE NEXT SLIDE →

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✅ ANSWERS — Reactivity Series

A1 [2 marks]

Most reactive → Least reactive: Magnesium, Zinc, Copper, Gold. (1 mark for correct position of Magnesium/Gold; 1 mark for correct full order)

A2 [3 marks]

Observation: The blue colour of the solution fades/goes pale green. Orange/red solid (copper) forms on the iron. (2 marks for observations) Explanation: Iron is more reactive than copper, so iron displaces copper from the solution. (1 mark)

A3 [4 marks]

(a) Most reactive first: D, A, B, C — D reacts explosively (most reactive), A vigorously, B slowly, C no reaction. (2 marks for correct full order) (b) Metal A would displace metal B from its sulfate solution because A is more reactive than B. The solution would change colour and a solid deposit of metal B would form. (2 marks)

A4 [2 marks]

Gold is very unreactive / low in the reactivity series (1 mark), so it does not react with oxygen or other compounds in the ground and exists in its pure/native form. (1 mark)

💡 Examiner Tip: Always use the word DISPLACE in displacement reaction answers!

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📝 EXAM QUESTIONS — Reactivity Series (Set 2)

1 QUESTION 1

[1 mark]

Which metal would react most vigorously with cold water?

A) Copper

B) Iron

C) Potassium

D) Zinc

2 QUESTION 2

[3 marks]

Lead oxide (PbO) can be reduced using carbon. Write a word equation for this reaction and explain why carbon can be used to extract lead but cannot be used to extract aluminium.

3 QUESTION 3

[4 marks]

A student places a piece of magnesium into zinc sulfate solution and a separate piece of magnesium into copper sulfate solution.

(a)Write a word equation for the reaction between magnesium and copper sulfate.[1]

(b)Write a balanced symbol equation for the reaction between magnesium and copper sulfate.[2]

(c)Which reaction would you expect to be more vigorous? Explain your answer.[1]

4 QUESTION 4

[2 marks]

Explain why iron objects left outdoors rust, but gold objects do not.

EXAM PREPARATION | REACTIVITY SERIES

⏱ Suggested time: 10 minutes | ATTEMPT BEFORE TURNING OVER →

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ANSWERS — Reactivity Series (Set 2)

A1 [1 mark]

C) Potassium ✓ — Potassium is the most reactive of the listed metals and reacts violently with cold water.

A2 [3 marks]

Word equation: lead oxide + carbon → lead + carbon dioxide (1 mark).

Carbon can reduce lead because carbon is MORE reactive than lead / higher in the reactivity series than lead (1 mark).

Carbon CANNOT reduce aluminium because aluminium is MORE reactive than carbon / higher in the reactivity series, so it must be extracted by electrolysis instead (1 mark).

A3 [4 marks]

(a) Magnesium + copper sulfate → magnesium sulfate + copper (1 mark)

(b) Mg + CuSO₄ → MgSO₄ + Cu — award 1 mark for correct formula, 1 mark for balance (2 marks)

(c) The reaction with copper sulfate would be more vigorous because there is a greater difference in reactivity between magnesium and copper than between magnesium and zinc (1 mark).

A4 [2 marks]

Iron is relatively reactive and reacts with oxygen and water in the air to form iron oxide (rust) (1 mark).

Gold is very unreactive / at the bottom of the reactivity series and does not react with oxygen or water (1 mark).

Examiner Tip: For extraction questions, always state which is MORE reactive — the metal or carbon.

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Part 2 Redox Reactions

Oxidation, Reduction & Electron Transfer

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OIL RIG

Oxidation and Reduction

OIL — Oxidation Is Loss

• Oxidation = LOSS of electrons
• The oxidised species LOSES electrons
OR: Oxidation = GAIN of oxygen

Example

Mg → Mg²⁺ + 2e⁻

(magnesium is OXIDISED)

RIG — Reduction Is Gain

• Reduction = GAIN of electrons
• The reduced species GAINS electrons
OR: Reduction = LOSS of oxygen

Example

Cu²⁺ + 2e⁻ → Cu

(copper ion is REDUCED)

⚡

REDOX reactions ALWAYS happen together — if something is oxidised, something else MUST be reduced at the same time!

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Redox in Displacement Reactions

Overall Reaction: Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s)

Oxidation Half-Equation

Zn → Zn²⁺ + 2e⁻

⇡

Zinc is OXIDISED

⇡

Zinc LOSES 2 electrons

Reduction Half-Equation

Cu²⁺ + 2e⁻ → Cu

⇡

Copper ion is REDUCED

⇡

Copper ion GAINS 2 electrons

⚡ The electrons lost by zinc are GAINED by copper ions. ⚡

Zinc = REDUCING AGENT

(it gets oxidised, causes reduction of copper)

Copper = OXIDISING AGENT

(it gets reduced, causes oxidation of zinc)

Colour change

Blue solution → Colourless

Orange copper solid forms

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Redox in Terms of Oxygen

Oxidation = Gain of Oxygen

2Mg + O₂ → 2MgO

Magnesium is OXIDISED (gains oxygen)

C + O₂ → CO₂

Carbon is OXIDISED

Fe + S → FeS

Iron is OXIDISED (gains non-metal)

Reduction = Loss of Oxygen

CuO + H₂ → Cu + H₂O

Copper oxide is REDUCED (loses oxygen)

PbO + C → Pb + CO₂

Lead oxide is REDUCED

Fe₂O₃ + 3CO → 2Fe + 3CO₂

Iron ore is REDUCED in a blast furnace

CuO + Mg → Cu + MgO

CuO is REDUCED (loses oxygen)

Mg is OXIDISED (gains oxygen)

THIS IS A REDOX REACTION

💡In the extraction of metals, the metal oxide is always REDUCED and the reducing agent (carbon/CO) is OXIDISED.

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📝 EXAM QUESTIONS — Redox Reactions

1 Mark

In the reaction:

Fe + CuSO₄ → FeSO₄ + Cu

Which species is oxidised?

A) Fe

B) Cu²⁺

C) SO₄²⁻

D) Fe²⁺

3 Marks

Zinc is added to silver nitrate solution.

(a) Write a word equation for this reaction. [1]

(b) Identify which substance is oxidised and which is reduced. [1]

4 Marks

The following reaction occurs in a blast furnace:

Fe₂O₃ + 3CO → 2Fe + 3CO₂

(a) Identify which substance is oxidised. [1]

(b) Identify which substance is reduced. [1]

(d) What is the role of carbon monoxide in this reaction? [1]

2 Marks

Define the term 'redox reaction'.

Use the terms oxidation and reduction in your answer.

⏱ Suggested time: 10 minutes | ATTEMPT BEFORE TURNING OVER →

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✅ ANSWERS — Redox Reactions

A1 [1 mark]

A) Fe ✓ — Iron loses electrons (Fe → Fe²⁺ + 2e⁻) so it is OXIDISED.

Remember OIL — Oxidation Is Loss of electrons.

A2 [3 marks]

(a) Zinc + silver nitrate → zinc nitrate + silver (1 mark)

(b) Zinc is oxidised; Silver ions (Ag⁺) are reduced. (1 mark)

(c) Zinc atoms LOSE electrons (Zn → Zn²⁺ + 2e⁻). These electrons are GAINED by silver ions (Ag⁺ + e⁻ → Ag). (1 mark)

A3 [4 marks]

(a) Carbon monoxide (CO) is oxidised — it gains oxygen to form CO₂. (1 mark)

(b) Iron oxide (Fe₂O₃) is reduced. (1 mark)

(c) Iron oxide LOSES oxygen — it goes from Fe₂O₃ to Fe (pure iron). Reduction = loss of oxygen. (1 mark)

(d) Carbon monoxide acts as the REDUCING AGENT — it removes oxygen from the iron oxide. (1 mark)

A4 [2 marks]

A redox reaction is a reaction in which oxidation and reduction occur simultaneously (1 mark).

One species loses electrons/gains oxygen (oxidation) while another species gains electrons/loses oxygen (reduction) at the same time. (1 mark)

💡 Examiner Tip: Always name BOTH the oxidised AND reduced species — half marks are common if you only name one!

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📝 EXAM QUESTIONS — Redox Reactions (Set 2)

Question 1

[2 marks]

In the reaction: 2H₂ + O₂ → 2H₂O.
(a) Is hydrogen oxidised or reduced? [1 mark]
(b) Is oxygen oxidised or reduced? [1 mark]

Question 2

[3 marks]

A student says: 'In a displacement reaction, the more reactive metal is always oxidised.' Explain whether the student is correct, using the example of magnesium reacting with iron sulfate solution.

Question 3

[4 marks]

Copper oxide is heated with hydrogen gas: CuO + H₂ → Cu + H₂O.
(a) Write down what is oxidised in this reaction. [1 mark]
(b) Write down what is reduced in this reaction. [1 mark]
(c) In terms of electrons, explain the process of reduction. [1 mark]
(d) What term do we use for a substance that causes the reduction of another substance? [1 mark]

Question 4

[2 marks]

Explain the meaning of the term 'reducing agent'. Give an example from a reaction you have studied.

⏱ Suggested time: 10 minutes | ATTEMPT BEFORE TURNING OVER →

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✅ ANSWERS — Redox Reactions (Set 2)

A1 [2 marks]

(a) Hydrogen is OXIDISED — it gains oxygen to form water. (1 mark)

(b) Oxygen is REDUCED — it gains electrons / is part of the reduction process. (1 mark)

NOTE: At foundation, accept 'oxygen causes oxidation of hydrogen'.

A2 [3 marks]

The student is CORRECT (1 mark).
In the reaction: Mg + FeSO₄ → MgSO₄ + Fe.

Magnesium (more reactive) is OXIDISED: Mg → Mg²⁺ + 2e⁻ — it loses electrons. (1 mark)

Iron ions (Fe²⁺) are REDUCED: Fe²⁺ + 2e⁻ → Fe — they gain electrons. The more reactive metal always loses electrons (is oxidised). (1 mark)

A3 [4 marks]

(a) Hydrogen (H₂) is oxidised — it gains oxygen. (1 mark)

(b) Copper oxide (CuO) is reduced — it loses oxygen. (1 mark)

(c) Reduction involves the GAIN of electrons. In this reaction, copper ions gain electrons to become copper atoms: Cu²⁺ + 2e⁻ → Cu. (1 mark)

(d) A REDUCING AGENT. (1 mark)

A4 [2 marks]

A reducing agent is a substance that CAUSES the reduction of another substance (1 mark).

It does this by donating electrons / being oxidised itself.

Example: Carbon acts as a reducing agent when it reduces iron oxide in the blast furnace:
Fe₂O₃ + 3C → 2Fe + 3CO₂ (1 mark)

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Part 3 Synthesis

Making Salts, Neutralisation & Salt Preparation Methods

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What is a Salt?

A SALT is an ionic compound formed when the hydrogen in an acid is replaced by a metal ion.

Acid

Salt Produced

Example

Hydrochloric acid (HCl)

Chloride salt

MgCl₂ — magnesium chloride

Sulfuric acid (H₂SO₄)

Sulfate salt

CuSO₄ — copper sulfate

Nitric acid (HNO₃)

Nitrate salt

NaNO₃ — sodium nitrate

Acid + Metal → Salt + Hydrogen

Acid + Metal Oxide → Salt + Water

Acid + Metal Hydroxide → Salt + Water

Acid + Metal Carbonate → Salt + Water + Carbon Dioxide

💡 The NAME of the salt comes from the METAL + the ACID used.

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Preparing Salts from Insoluble Bases (Core Practical)

Example: Making Copper Sulfate from Copper Oxide + Sulfuric Acid

Step 1

Add EXCESS copper oxide (CuO) powder to warm dilute sulfuric acid (H₂SO₄) in a beaker. Stir continuously.

Step 2

The solution turns BLUE as copper sulfate forms. Excess copper oxide remains — this shows all acid has been used.

Step 3

FILTER the mixture through filter paper in a funnel to remove excess copper oxide.

Step 4

Pour the blue copper sulfate filtrate into an evaporating dish.

Step 5

Gently HEAT the solution to evaporate some water — stop when crystals begin to form at the edges.

Step 6

Leave to COOL and CRYSTALLISE. Pat dry with filter paper.

Chemical Equation

CuO(s) + H₂SO₄(aq) → CuSO₄(aq) + H₂O(l)

Exam Tip

⚠️ We use EXCESS base to ensure all the acid is neutralised.

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Preparing Salts from Soluble Bases — Titration Method

Used when the base is SOLUBLE (e.g. sodium hydroxide, potassium hydroxide)

Fill a BURETTE with dilute acid. Fill a pipette with the alkali solution and transfer exact volume to a conical flask. Add 2-3 drops of INDICATOR.

Slowly add acid from burette to alkali, swirling constantly. Stop when the indicator changes colour (end point). Record the volume of acid used.

REPEAT the titration WITHOUT indicator using the exact same volumes. (Indicator would contaminate the salt.)

Transfer the neutralised solution to an evaporating dish. Heat gently to evaporate most of the water.

Leave to cool and crystallise. Collect and dry the pure salt crystals.

Example Definition

NaOH + HCl → NaCl + H₂O

(sodium hydroxide + hydrochloric acid → sodium chloride + water)

💡 We repeat without indicator because we want a PURE salt — the indicator would contaminate it.

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Solubility Rules

You need to know which salts are SOLUBLE and which are INSOLUBLE

Salt Type	Solubility	Exceptions
Sodium, Potassium & Ammonium salts	ALL SOLUBLE	None
Nitrates (NO₃⁻)	ALL SOLUBLE	None
Chlorides (Cl⁻)	MOST SOLUBLE	Lead chloride and Silver chloride are INSOLUBLE
Sulfates (SO₄²⁻)	MOST SOLUBLE	Barium sulfate, Lead sulfate, Calcium sulfate are INSOLUBLE
Carbonates (CO₃²⁻)	MOST INSOLUBLE	Sodium, Potassium & Ammonium carbonates are soluble
Hydroxides (OH⁻)	MOST INSOLUBLE	Sodium, Potassium & Ammonium hydroxides are soluble

💡

Solubility rules help us choose the right METHOD for making a salt — insoluble bases use the excess method, soluble bases need titration.

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📝 EXAM QUESTIONS — Synthesis (Set 1)

A student wants to make copper chloride salt. Name the acid and the base she should use, and write a word equation for the reaction.

[2 marks]

Describe how you would prepare pure, dry crystals of zinc sulfate starting from zinc oxide and dilute sulfuric acid. Your answer should include the reason why excess zinc oxide is added.

[4 marks]

A student adds calcium carbonate to hydrochloric acid. (a) Write a word equation for this reaction. [1 mark] (b) Describe two observations the student would make. [2 marks]

[3 marks]

Explain why a titration method must be used to prepare sodium chloride from sodium hydroxide and hydrochloric acid, rather than the excess base method.

[3 marks]

⏱ Suggested time: 12 minutes | ATTEMPT BEFORE TURNING OVER →

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ANSWERS — Synthesis (Set 1)

Question 1

[2 marks]

Acid: Hydrochloric acid (HCl) ✓

Base: Copper oxide (CuO) ✓

Word equation: Copper oxide + hydrochloric acid → copper chloride + water.

Question 3

[3 marks]

(a) Calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide. (1 mark)

(b) Any two from:

Bubbles/fizzing observed (effervescence) ✓
Solid calcium carbonate dissolves/disappears ✓
The solution warms up slightly ✓
CO₂ gas produced turns limewater milky (if tested) ✓

(2 marks)

Question 2

[4 marks]

Step 1: Add excess zinc oxide to warm dilute sulfuric acid and stir. (1 mark)

Step 2: Filter the mixture to remove excess zinc oxide. (1 mark)

Step 3: Heat the filtrate (zinc sulfate solution) in an evaporating dish to concentrate it. (1 mark)

Step 4: Allow to cool and crystallise; dry the crystals. (1 mark)

Reason for excess zinc oxide: to ensure ALL the acid is neutralised / used up, so the final salt is not contaminated with acid. (already credited in mark scheme)

Question 4

[3 marks]

Sodium hydroxide is a SOLUBLE base (1 mark), so it cannot be filtered out if added in excess — it would contaminate the salt (1 mark)

Titration is used to find the exact volumes needed so that all the acid and alkali are neutralised completely, producing a pure salt. (1 mark)

Examiner Tip: In 4-mark method questions, aim for 4 distinct steps — each step = 1 mark!

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📝 EXAM QUESTIONS — Synthesis (Set 2)

Q1 Which of the following salts is INSOLUBLE in water? [1 mark]

A) Sodium carbonate

B) Potassium nitrate

C) Copper carbonate

D) Ammonium chloride

Q2 A student carries out a titration to make potassium chloride. She uses potassium hydroxide solution and hydrochloric acid with methyl orange indicator. [4 marks]

(a)

Describe how the student would know she has reached the end point. [1 mark]

(b)

She then repeats the experiment without the indicator. Explain why. [1 mark]

(c)

Describe the final two steps to obtain pure potassium chloride crystals. [2 marks]

Q3 Write balanced symbol equations for the following reactions: [3 marks]

(a)

Magnesium + sulfuric acid [1 mark]

(b)

Sodium hydroxide + hydrochloric acid [1 mark]

(c)

Zinc carbonate + nitric acid [1 mark]

Q4 A student is asked to make lead sulfate. She suggests adding lead to sulfuric acid. Explain why this method would NOT work and suggest a better method. [3 marks]

Suggested time: 12 minutes | ATTEMPT BEFORE TURNING OVER →

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GCSE Foundation Chemistry: Reactivity, Redox & Synthesis

Master GCSE Chemistry with this guide on the reactivity series, redox reactions, extraction of metals, and salt synthesis methods for Edexcel Foundation.

GCSE Foundation Chemistry

Reactivity Series | Redox Reactions | Synthesis

Edexcel | 2 Hour Lesson

Lesson Overview

Part 1: Reactivity Series

The reactivity series order

Displacement reactions

Reactions with water & acids

Extracting metals

Part 2: Redox Reactions

Oxidation & reduction

OIL RIG mnemonic

Electron transfer

Identifying redox reactions

Part 3: Synthesis

Making salts

Neutralisation reactions

Salt preparation methods

Core practical

⏱ 2 Hour Lesson | Edexcel GCSE Foundation Chemistry

Part 1

Reactivity Series

Ordering metals, displacement reactions & extracting metals from ores

The Reactivity Series

Reaction Key

React with cold water

React with steam only

React with dilute acid

Very unreactive

"Please Send Little Cats Meowing About Zebras In The Lovely Calm Seas Going"

<div style="display: flex; align-items: center; justify-content: space-between; background-color: #0b3d54; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">1.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Potassium (K)</span> <span style="color: #a0aec0; font-weight: 400; font-size: 20px; margin-left: 15px;">- most reactive</span> </div> <span style="font-size: 24px;">🔵</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #111a2f; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">2.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Sodium (Na)</span> </div> <span style="font-size: 24px;">🔵</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #0b3d54; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">3.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Lithium (Li)</span> </div> <span style="font-size: 24px;">🔵</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #111a2f; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">4.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Calcium (Ca)</span> </div> <span style="font-size: 24px;">🔵</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #0b3d54; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">5.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Magnesium (Mg)</span> </div> <span style="font-size: 24px;">🟡</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #111a2f; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">6.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Aluminium (Al)</span> </div> <span style="font-size: 24px;">🟡</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #0b3d54; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">7.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Zinc (Zn)</span> </div> <span style="font-size: 24px;">🟡</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #111a2f; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">8.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Iron (Fe)</span> </div> <span style="font-size: 24px;">🟡</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #0b3d54; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">9.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Tin (Sn)</span> </div> <span style="font-size: 24px;">🔴</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #111a2f; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">10.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Lead (Pb)</span> </div> <span style="font-size: 24px;">🔴</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: rgba(255, 215, 0, 0.12); padding: 0 25px; border-radius: 8px; flex: 1; border: 2px dashed rgba(255, 215, 0, 0.6);"> <div style="display: flex; align-items: baseline;"> <span style="color: #ffd700; font-weight: 700; font-size: 22px; width: 45px;">11.</span> <span style="color: #ffd700; font-weight: 800; font-size: 26px; letter-spacing: 0.5px;">HYDROGEN (H)</span> </div> <span style="color: #ffd700; font-size: 16px; font-weight: 600; font-style: italic;">non-metal</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #111a2f; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">12.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Copper (Cu)</span> </div> <span style="font-size: 24px;">⚫</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #0b3d54; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">13.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Silver (Ag)</span> </div> <span style="font-size: 24px;">⚫</span> </div> <div style="display: flex; align-items: center; justify-content: space-between; background-color: #111a2f; padding: 0 25px; border-radius: 8px; flex: 1;"> <div style="display: flex; align-items: baseline;"> <span style="color: #00d2ff; font-weight: 700; font-size: 22px; width: 45px;">14.</span> <span style="color: #ffffff; font-weight: 600; font-size: 26px;">Gold (Au)</span> <span style="color: #a0aec0; font-weight: 400; font-size: 20px; margin-left: 15px;">- least reactive</span> </div> <span style="font-size: 24px;">⚫</span> </div>

Reactions with Water and Acids

Reactions with Water

Reactions with Dilute Acids

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

The gas produced is always HYDROGEN — tested with a lit splint (squeaky pop!)

Displacement Reactions

reactive metal will

DISPLACE

LESS

reactive metal from its salt solution.

Reaction Occurs

Zn + CuSO₄ → ZnSO₄ + Cu

Blue solution goes colourless, orange/red copper metal forms

Reaction Occurs

Fe + CuSO₄ → FeSO₄ + Cu

Blue solution fades, copper deposits on iron

No Reaction

Cu + ZnSO₄ → No reaction

No change — copper is LESS reactive than zinc

More reactive =

pushes the less reactive metal

OUT

of its compound.

Extracting Metals from Ores

How a metal is extracted depends on its position in the reactivity series.

Very Reactive Metals

Potassium, Sodium, Lithium, Calcium, Magnesium, Aluminium

ELECTROLYSIS

Too reactive to be reduced by carbon. Requires large amounts of electricity.

Moderately Reactive Metals

Zinc, Iron, Tin, Lead

REDUCTION WITH CARBON

ZnO + C → Zn + CO₂

Carbon is more reactive than these metals so it displaces them.

Unreactive Metals

Copper, Silver, Gold

FOUND NATIVE or SIMPLE HEATING

So unreactive they exist as pure metals in the ground.

Aluminium is extracted by electrolysis despite being common — its oxide is very stable.

📝 EXAM QUESTIONS — Reactivity Series

Place the following metals in order of reactivity, starting with the most reactive: Copper, Magnesium, Zinc, Gold

Iron is added to copper sulfate solution. Describe what you would observe and explain why this reaction occurs.

Place metals A, B, C, D in order of reactivity, most reactive first.

Predict what would happen if metal A was added to a solution of metal B sulfate.

Explain why gold is found as a pure metal in the ground, whereas aluminium is not.

⏱ Suggested time: 10 minutes | Put your pen down when done!

ATTEMPT THESE BEFORE LOOKING AT THE NEXT SLIDE →

✅ ANSWERS — Reactivity Series

A1 [2 marks]

Most reactive → Least reactive: Magnesium, Zinc, Copper, Gold. (1 mark for correct position of Magnesium/Gold; 1 mark for correct full order)

A2 [3 marks]

A3 [4 marks]

A4 [2 marks]

Gold is very unreactive / low in the reactivity series (1 mark), so it does not react with oxygen or other compounds in the ground and exists in its pure/native form. (1 mark)

💡 Examiner Tip:

Always use the word DISPLACE in displacement reaction answers!

📝 EXAM QUESTIONS — Reactivity Series (Set 2)

[1 mark]

Which metal would react most vigorously with cold water?<br><br><div style="display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin-top: 5px; padding-left: 10px;"><div><b style='color:#ffb347; margin-right: 10px;'>A)</b> Copper</div><div><b style='color:#ffb347; margin-right: 10px;'>B)</b> Iron</div><div><b style='color:#ffb347; margin-right: 10px;'>C)</b> Potassium</div><div><b style='color:#ffb347; margin-right: 10px;'>D)</b> Zinc</div></div>

[3 marks]

Lead oxide (PbO) can be reduced using carbon. Write a word equation for this reaction and explain why carbon can be used to extract lead but cannot be used to extract aluminium.

[4 marks]

A student places a piece of magnesium into zinc sulfate solution and a separate piece of magnesium into copper sulfate solution.<br><br><div style='display: flex; gap: 12px; margin-bottom: 16px;'><b style='color:#ffb347; white-space: nowrap;'>(a)</b><span style='flex-grow: 1;'>Write a word equation for the reaction between magnesium and copper sulfate.</span><span style='color:#a0aec0; font-size:22px; white-space: nowrap;'>[1]</span></div><div style='display: flex; gap: 12px; margin-bottom: 16px;'><b style='color:#ffb347; white-space: nowrap;'>(b)</b><span style='flex-grow: 1;'>Write a balanced symbol equation for the reaction between magnesium and copper sulfate.</span><span style='color:#a0aec0; font-size:22px; white-space: nowrap;'>[2]</span></div><div style='display: flex; gap: 12px;'><b style='color:#ffb347; white-space: nowrap;'>(c)</b><span style='flex-grow: 1;'>Which reaction would you expect to be more vigorous? Explain your answer.</span><span style='color:#a0aec0; font-size:22px; white-space: nowrap;'>[1]</span></div>

[2 marks]

Explain why iron objects left outdoors rust, but gold objects do not.

⏱ Suggested time: 10 minutes | ATTEMPT BEFORE TURNING OVER →

ANSWERS — Reactivity Series (Set 2)

Examiner Tip:

For extraction questions, always state which is MORE reactive — the metal or carbon.

A1 [1 mark]

A2 [3 marks]

A3 [4 marks]

A4 [2 marks]

Part 2

Redox Reactions

Oxidation, Reduction & Electron Transfer

OIL RIG

Oxidation and Reduction

OIL — Oxidation Is Loss

Oxidation = <b>LOSS</b> of electrons

The oxidised species <b>LOSES</b> electrons

Oxidation = GAIN of oxygen

Mg → Mg²⁺ + 2e⁻

(magnesium is OXIDISED)

RIG — Reduction Is Gain

Reduction = <b>GAIN</b> of electrons

The reduced species <b>GAINS</b> electrons

Reduction = LOSS of oxygen

Cu²⁺ + 2e⁻ → Cu

(copper ion is REDUCED)

REDOX reactions <b>ALWAYS</b> happen together — if something is oxidised, something else <b>MUST</b> be reduced at the same time!

Redox in Displacement Reactions

Overall Reaction:

Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s)

Oxidation Half-Equation

Zn → Zn²⁺ + 2e⁻

Zinc is OXIDISED

Zinc LOSES 2 electrons

Reduction Half-Equation

Cu²⁺ + 2e⁻ → Cu

Copper ion is REDUCED

Copper ion GAINS 2 electrons

The electrons lost by zinc are GAINED by copper ions.

Zinc = REDUCING AGENT

(it gets oxidised, causes reduction of copper)

Copper = OXIDISING AGENT

(it gets reduced, causes oxidation of zinc)

Colour change

Blue solution → Colourless

Orange copper solid forms

Redox in Terms of Oxygen

Oxidation = Gain of Oxygen

Reduction = Loss of Oxygen

2Mg + O₂ → 2MgO

Magnesium is <strong style="color:#00e5ff;">OXIDISED</strong> (gains oxygen)

C + O₂ → CO₂

Carbon is <strong style="color:#00e5ff;">OXIDISED</strong>

Fe + S → FeS

Iron is <strong style="color:#00e5ff;">OXIDISED</strong> (gains non-metal)

CuO + H₂ → Cu + H₂O

Copper oxide is <strong style="color:#d500f9;">REDUCED</strong> (loses oxygen)

PbO + C → Pb + CO₂

Lead oxide is <strong style="color:#d500f9;">REDUCED</strong>

Fe₂O₃ + 3CO → 2Fe + 3CO₂

Iron ore is <strong style="color:#d500f9;">REDUCED</strong> in a blast furnace

CuO + Mg → Cu + MgO

CuO is <strong style="color:#d500f9; font-weight:800;">REDUCED</strong> (loses oxygen)

Mg is <strong style="color:#00e5ff; font-weight:800;">OXIDISED</strong> (gains oxygen)

THIS IS A REDOX REACTION

<span style="color:#ffeb3b; font-size:28px; margin-right:8px; vertical-align:middle;">💡</span><span style="vertical-align:middle;">In the extraction of metals, the metal oxide is always <strong style="color:#d500f9;">REDUCED</strong> and the reducing agent (carbon/CO) is <strong style="color:#00e5ff;">OXIDISED</strong>.</span>

📝 EXAM QUESTIONS — Redox Reactions

1 Mark

<div style="margin-bottom: 15px;">In the reaction:</div> <div style="font-size: 28px; font-weight: bold; font-family: 'Consolas', 'Courier New', monospace; background: rgba(0,0,0,0.3); padding: 15px; text-align: center; margin-bottom: 25px; border-radius: 8px;">Fe + CuSO₄ → FeSO₄ + Cu</div> <div style="margin-bottom: 20px; font-weight: 600;">Which species is oxidised?</div> <div style="display: grid; grid-template-columns: 1fr 1fr; gap: 15px;"> <div style="background: rgba(255,255,255,0.08); padding: 12px 20px; border-radius: 8px; border: 1px solid rgba(255,255,255,0.1);"><span style="color: #00d2ff; font-weight: bold; margin-right: 15px;">A)</span> Fe</div> <div style="background: rgba(255,255,255,0.08); padding: 12px 20px; border-radius: 8px; border: 1px solid rgba(255,255,255,0.1);"><span style="color: #00d2ff; font-weight: bold; margin-right: 15px;">B)</span> Cu²⁺</div> <div style="background: rgba(255,255,255,0.08); padding: 12px 20px; border-radius: 8px; border: 1px solid rgba(255,255,255,0.1);"><span style="color: #00d2ff; font-weight: bold; margin-right: 15px;">C)</span> SO₄²⁻</div> <div style="background: rgba(255,255,255,0.08); padding: 12px 20px; border-radius: 8px; border: 1px solid rgba(255,255,255,0.1);"><span style="color: #00d2ff; font-weight: bold; margin-right: 15px;">D)</span> Fe²⁺</div> </div>

3 Marks

<div style="margin-bottom: 20px;">Zinc is added to silver nitrate solution.</div> <div style="display: flex; gap: 15px; margin-bottom: 12px;"><span style="color: #00d2ff; font-weight: 700;">(a)</span> <span style="flex-grow: 1;">Write a word equation for this reaction.</span> <span style="font-size: 20px; color: rgba(0, 210, 255, 0.7);">[1]</span></div> <div style="display: flex; gap: 15px; margin-bottom: 12px;"><span style="color: #00d2ff; font-weight: 700;">(b)</span> <span style="flex-grow: 1;">Identify which substance is oxidised and which is reduced.</span> <span style="font-size: 20px; color: rgba(0, 210, 255, 0.7);">[1]</span></div> <div style="display: flex; gap: 15px; margin-bottom: 12px;"><span style="color: #00d2ff; font-weight: 700;">(c)</span> <span style="flex-grow: 1;">Explain what happens to electrons during this reaction.</span> <span style="font-size: 20px; color: rgba(0, 210, 255, 0.7);">[1]</span></div>

4 Marks

<div style="margin-bottom: 10px;">The following reaction occurs in a blast furnace:</div> <div style="font-size: 26px; font-weight: bold; font-family: 'Consolas', 'Courier New', monospace; background: rgba(0,0,0,0.3); padding: 12px; text-align: center; margin-bottom: 15px; border-radius: 8px;">Fe₂O₃ + 3CO → 2Fe + 3CO₂</div> <div style="display: flex; gap: 12px; margin-bottom: 8px;"><span style="color: #00d2ff; font-weight: 700;">(a)</span> <span style="flex-grow: 1;">Identify which substance is oxidised.</span> <span style="font-size: 18px; color: rgba(0, 210, 255, 0.7);">[1]</span></div> <div style="display: flex; gap: 12px; margin-bottom: 8px;"><span style="color: #00d2ff; font-weight: 700;">(b)</span> <span style="flex-grow: 1;">Identify which substance is reduced.</span> <span style="font-size: 18px; color: rgba(0, 210, 255, 0.7);">[1]</span></div> <div style="display: flex; gap: 12px; margin-bottom: 8px;"><span style="color: #00d2ff; font-weight: 700;">(c)</span> <span style="flex-grow: 1;">Explain, in terms of oxygen, why iron oxide is reduced.</span> <span style="font-size: 18px; color: rgba(0, 210, 255, 0.7);">[1]</span></div> <div style="display: flex; gap: 12px;"><span style="color: #00d2ff; font-weight: 700;">(d)</span> <span style="flex-grow: 1;">What is the role of carbon monoxide in this reaction?</span> <span style="font-size: 18px; color: rgba(0, 210, 255, 0.7);">[1]</span></div>

2 Marks

<div style="margin-bottom: 25px; font-size: 28px; line-height: 1.5;">Define the term <strong>'redox reaction'</strong>.</div> <div style="background: rgba(245, 158, 11, 0.1); border-left: 4px solid #f59e0b; padding: 20px 25px; border-radius: 0 8px 8px 0; font-style: italic;"> Use the terms <span style="color: #f59e0b; font-weight: 700; font-style: normal;">oxidation</span> and <span style="color: #f59e0b; font-weight: 700; font-style: normal;">reduction</span> in your answer. </div>

⏱ Suggested time: 10 minutes | ATTEMPT BEFORE TURNING OVER →

✅ ANSWERS — Redox Reactions

A1 [1 mark]

A) Fe ✓ — Iron loses electrons (Fe → Fe²⁺ + 2e⁻) so it is <strong style="color: #ffffff;">OXIDISED</strong>.<br><br>Remember OIL — Oxidation Is Loss of electrons.

A2 [3 marks]

<span style="color: #00e676; font-weight: 600;">(a)</span> Zinc + silver nitrate → zinc nitrate + silver (1 mark)<br><br><span style="color: #00e676; font-weight: 600;">(b)</span> Zinc is oxidised; Silver ions (Ag⁺) are reduced. (1 mark)<br><br><span style="color: #00e676; font-weight: 600;">(c)</span> Zinc atoms <strong style="color: #ffffff;">LOSE</strong> electrons (Zn → Zn²⁺ + 2e⁻). These electrons are <strong style="color: #ffffff;">GAINED</strong> by silver ions (Ag⁺ + e⁻ → Ag). (1 mark)

A3 [4 marks]

<span style="color: #00e676; font-weight: 600;">(a)</span> Carbon monoxide (CO) is oxidised — it gains oxygen to form CO₂. (1 mark)<br><br><span style="color: #00e676; font-weight: 600;">(b)</span> Iron oxide (Fe₂O₃) is reduced. (1 mark)<br><br><span style="color: #00e676; font-weight: 600;">(c)</span> Iron oxide <strong style="color: #ffffff;">LOSES</strong> oxygen — it goes from Fe₂O₃ to Fe (pure iron). Reduction = loss of oxygen. (1 mark)<br><br><span style="color: #00e676; font-weight: 600;">(d)</span> Carbon monoxide acts as the <strong style="color: #ffffff;">REDUCING AGENT</strong> — it removes oxygen from the iron oxide. (1 mark)

A4 [2 marks]

A redox reaction is a reaction in which oxidation and reduction occur simultaneously <span style="color: #8bb1d6;">(1 mark)</span>.<br><br>One species loses electrons/gains oxygen (oxidation) while another species gains electrons/loses oxygen (reduction) at the same time. <span style="color: #8bb1d6;">(1 mark)</span>

💡 Examiner Tip: Always name BOTH the oxidised AND reduced species — half marks are common if you only name one!

📝 EXAM QUESTIONS — Redox Reactions (Set 2)

In the reaction: 2H₂ + O₂ → 2H₂O. (a) Is hydrogen oxidised or reduced? [1 mark] (b) Is oxygen oxidised or reduced? [1 mark]

A student says: 'In a displacement reaction, the more reactive metal is always oxidised.' Explain whether the student is correct, using the example of magnesium reacting with iron sulfate solution.

Copper oxide is heated with hydrogen gas: CuO + H₂ → Cu + H₂O. (a) Write down what is oxidised in this reaction. [1 mark] (b) Write down what is reduced in this reaction. [1 mark] (c) In terms of electrons, explain the process of reduction. [1 mark] (d) What term do we use for a substance that causes the reduction of another substance? [1 mark]

Explain the meaning of the term 'reducing agent'. Give an example from a reaction you have studied.

✅ ANSWERS — Redox Reactions (Set 2)

[2 marks]

<div style='margin-bottom: 12px;'>(a) Hydrogen is <span style='color: #ffffff; font-weight: 700;'>OXIDISED</span> — it gains oxygen to form water. <span style='color: #00d2ff; font-weight: 700;'>(1 mark)</span></div><div style='margin-bottom: 12px;'>(b) Oxygen is <span style='color: #ffffff; font-weight: 700;'>REDUCED</span> — it gains electrons / is part of the reduction process. <span style='color: #00d2ff; font-weight: 700;'>(1 mark)</span></div><div style='color: #94a3b8; font-size: 20px; font-style: italic; background: rgba(0,0,0,0.25); padding: 12px 18px; border-left: 4px solid #64748b; border-radius: 6px; margin-top: 15px;'>NOTE: At foundation, accept 'oxygen causes oxidation of hydrogen'.</div>

[3 marks]

<div style='margin-bottom: 14px;'>The student is <span style='color: #4ade80; font-weight: 700;'>CORRECT</span> <span style='color: #00d2ff; font-weight: 700;'>(1 mark)</span>. <br>In the reaction: <span style='color: #ffffff; font-weight: 600;'>Mg + FeSO₄ → MgSO₄ + Fe</span>.</div><div style='margin-bottom: 14px;'>Magnesium (more reactive) is <span style='color: #ffffff; font-weight: 700;'>OXIDISED</span>: Mg → Mg²⁺ + 2e⁻ — it loses electrons. <span style='color: #00d2ff; font-weight: 700;'>(1 mark)</span></div><div>Iron ions (Fe²⁺) are <span style='color: #ffffff; font-weight: 700;'>REDUCED</span>: Fe²⁺ + 2e⁻ → Fe — they gain electrons. The more reactive metal always loses electrons (is oxidised). <span style='color: #00d2ff; font-weight: 700;'>(1 mark)</span></div>

[4 marks]

<div style='margin-bottom: 14px;'>(a) Hydrogen (H₂) is oxidised — it gains oxygen. <span style='color: #00d2ff; font-weight: 700;'>(1 mark)</span></div><div style='margin-bottom: 14px;'>(b) Copper oxide (CuO) is reduced — it loses oxygen. <span style='color: #00d2ff; font-weight: 700;'>(1 mark)</span></div><div style='margin-bottom: 14px;'>(c) Reduction involves the <span style='color: #ffffff; font-weight: 700;'>GAIN</span> of electrons. In this reaction, copper ions gain electrons to become copper atoms: <span style='color: #ffffff; font-weight: 600;'>Cu²⁺ + 2e⁻ → Cu</span>. <span style='color: #00d2ff; font-weight: 700;'>(1 mark)</span></div><div>(d) A <span style='color: #ffffff; font-weight: 700;'>REDUCING AGENT</span>. <span style='color: #00d2ff; font-weight: 700;'>(1 mark)</span></div>

[2 marks]

<div style='margin-bottom: 14px;'>A reducing agent is a substance that <span style='color: #ffffff; font-weight: 700;'>CAUSES</span> the reduction of another substance <span style='color: #00d2ff; font-weight: 700;'>(1 mark)</span>.</div><div style='margin-bottom: 14px;'>It does this by donating electrons / being oxidised itself.</div><div style='background: rgba(0, 210, 255, 0.08); padding: 18px; border-radius: 8px; border-left: 4px solid #00d2ff; line-height: 1.4;'><span style='color: #00d2ff; font-style: italic; font-weight: 600;'>Example:</span> Carbon acts as a reducing agent when it reduces iron oxide in the blast furnace:<br><span style='color: #ffffff; font-weight: 600; display: inline-block; margin-top: 8px;'>Fe₂O₃ + 3C → 2Fe + 3CO₂</span> <span style='color: #00d2ff; font-weight: 700;'>(1 mark)</span></div>

Part 3

Synthesis

Making Salts, Neutralisation & Salt Preparation Methods

What is a Salt?

Preparing Salts from Insoluble Bases (Core Practical)

Example: Making Copper Sulfate from Copper Oxide + Sulfuric Acid

Add EXCESS copper oxide (CuO) powder to warm dilute sulfuric acid (H₂SO₄) in a beaker. Stir continuously.

The solution turns BLUE as copper sulfate forms. Excess copper oxide remains — this shows all acid has been used.

FILTER the mixture through filter paper in a funnel to remove excess copper oxide.

Pour the blue copper sulfate filtrate into an evaporating dish.

Gently HEAT the solution to evaporate some water — stop when crystals begin to form at the edges.

Leave to COOL and CRYSTALLISE. Pat dry with filter paper.

CuO(s) + H₂SO₄(aq) → CuSO₄(aq) + H₂O(l)

⚠️ We use EXCESS base to ensure all the acid is neutralised.

Preparing Salts from Soluble Bases — Titration Method

Used when the base is SOLUBLE (e.g. sodium hydroxide, potassium hydroxide)

Fill a BURETTE with dilute acid. Fill a pipette with the alkali solution and transfer exact volume to a conical flask. Add 2-3 drops of INDICATOR.

Slowly add acid from burette to alkali, swirling constantly. Stop when the indicator changes colour (end point). Record the volume of acid used.

REPEAT the titration WITHOUT indicator using the exact same volumes. (Indicator would contaminate the salt.)

Transfer the neutralised solution to an evaporating dish. Heat gently to evaporate most of the water.

Leave to cool and crystallise. Collect and dry the pure salt crystals.

NaOH + HCl → NaCl + H₂O

(sodium hydroxide + hydrochloric acid → sodium chloride + water)

We repeat without indicator because we want a PURE salt — the indicator would contaminate it.

Solubility Rules

You need to know which salts are SOLUBLE and which are INSOLUBLE

Solubility rules help us choose the right METHOD for making a salt — insoluble bases use the excess method, soluble bases need titration.

📝 EXAM QUESTIONS — Synthesis (Set 1)

A student wants to make copper chloride salt. Name the acid and the base she should use, and write a word equation for the reaction.

[2 marks]

Describe how you would prepare pure, dry crystals of zinc sulfate starting from zinc oxide and dilute sulfuric acid. Your answer should include the reason why excess zinc oxide is added.

[4 marks]

A student adds calcium carbonate to hydrochloric acid. (a) Write a word equation for this reaction. [1 mark] (b) Describe two observations the student would make. [2 marks]

[3 marks]

Explain why a titration method must be used to prepare sodium chloride from sodium hydroxide and hydrochloric acid, rather than the excess base method.

[3 marks]

⏱ Suggested time: 12 minutes | ATTEMPT BEFORE TURNING OVER →

ANSWERS — Synthesis (Set 1)

[2 marks]

Hydrochloric acid (HCl)

Copper oxide (CuO)

Copper oxide + hydrochloric acid → copper chloride + water.

[4 marks]

Add excess zinc oxide to warm dilute sulfuric acid and stir.

Filter the mixture to remove excess zinc oxide.

Heat the filtrate (zinc sulfate solution) in an evaporating dish to concentrate it.

Allow to cool and crystallise; dry the crystals.

to ensure ALL the acid is neutralised / used up, so the final salt is not contaminated with acid. (already credited in mark scheme)

[3 marks]

Calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide.

Any two from:

Bubbles/fizzing observed (effervescence)

Solid calcium carbonate dissolves/disappears

The solution warms up slightly

CO₂ gas produced turns limewater milky (if tested)

[3 marks]

SOLUBLE base

so it cannot be filtered out if added in excess — it would contaminate the salt

Titration is used to find the exact volumes needed so that all the acid and alkali are neutralised completely, producing a pure salt.

Examiner Tip: In 4-mark method questions, aim for 4 distinct steps — each step = 1 mark!

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GCSE Foundation Chemistry

Reactivity Series | Redox Reactions | Synthesis

Lesson Overview

Part 1: Reactivity Series

Part 2: Redox Reactions

Part 3: Synthesis

Part 1

Reactivity Series

The Reactivity Series

Reaction Key

Mnemonic

Reactions with Water and Acids

Reactions with Water

Reactions with Dilute Acids

Displacement Reactions

✅ Reaction Occurs

✅ Reaction Occurs

❌ No Reaction

Remember

Extracting Metals from Ores

How a metal is extracted depends on its position in the reactivity series.

Very Reactive Metals

Moderately Reactive Metals

Unreactive Metals

📝 EXAM QUESTIONS — Reactivity Series

Question 1

Question 2

Question 3

Question 4

✅ ANSWERS — Reactivity Series

A1 [2 marks]

A2 [3 marks]

A3 [4 marks]

A4 [2 marks]

📝 EXAM QUESTIONS — Reactivity Series (Set 2)

1 QUESTION 1

2 QUESTION 2

3 QUESTION 3

4 QUESTION 4

Part 2

Redox Reactions

OIL RIG

Oxidation and Reduction

OIL — Oxidation Is Loss

RIG — Reduction Is Gain

Redox in Displacement Reactions

Oxidation Half-Equation

Reduction Half-Equation

Redox in Terms of Oxygen

Oxidation = Gain of Oxygen

Reduction = Loss of Oxygen

📝 EXAM QUESTIONS — Redox Reactions

✅ ANSWERS — Redox Reactions

A1 [1 mark]

A2 [3 marks]

A3 [4 marks]

A4 [2 marks]

📝 EXAM QUESTIONS — Redox Reactions (Set 2)

Question 1

Question 2

Question 3

Question 4

✅ ANSWERS — Redox Reactions (Set 2)

Part 3

Synthesis

Making Salts, Neutralisation & Salt Preparation Methods

What is a Salt?

Preparing Salts from Insoluble Bases (Core Practical)

Example: Making Copper Sulfate from Copper Oxide + Sulfuric Acid

Preparing Salts from Soluble Bases — Titration Method

Used when the base is SOLUBLE (e.g. sodium hydroxide, potassium hydroxide)

Solubility Rules

You need to know which salts are SOLUBLE and which are INSOLUBLE

📝 EXAM QUESTIONS — Synthesis (Set 1)

ANSWERS — Synthesis (Set 1)

Question 1

Question 3

Question 2

Question 4

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