Reactivity Series And Corrosion Of Metals

Learn it by playing

Answer these questions to earn energy, then fish and explore. No account needed.

For teachers: ready-to-use lesson slides, revision notes, diagrams for Reactivity Series And Corrosion Of Metals (Co-ordinated Sciences (Double Award) [CIE], Chemistry) — use them in your lesson, or run the topic as a live class game.

Notes

Reactivity Series

The **reactivity series** lists metals in order of their reactivity based on reactions with water and acids.
Non-metals **carbon** and **hydrogen** are included for extraction and acid reactions.
Order (most to least reactive): **Potassium > Sodium > Calcium > Magnesium > Aluminium > Carbon > Zinc > Iron > Hydrogen > Copper > Silver > Gold**.
Mnemonic: 'Please send cats, monkeys and cute zebras into hot countries signed Gordon'.

Reactions with Water and Steam

Potassium, sodium, and calcium react with **cold water** to produce metal hydroxide and hydrogen gas.
Example: 2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g).
Magnesium reacts with **steam** to produce magnesium oxide and hydrogen: Mg(s) + H₂O(g) → MgO(s) + H₂(g).
Reactivity with water decreases down the series: potassium reacts violently, sodium quickly, calcium less strongly.

Reactions with Dilute Hydrochloric Acid

Metals **above hydrogen** in the series react with dilute HCl to form a salt and hydrogen gas.
Example: $Mg(s) + 2HCl(aq)$ → MgCl₂(aq) + H₂(g).
The more reactive the metal, the more **vigorous** the reaction.
Metals **below hydrogen** (copper, silver, gold) do **not** react with dilute HCl.

Displacement Reactions

A more reactive metal can **displace** a less reactive metal from a solution of its salt.
Example: Mg(s) + CuSO₄(aq) → MgSO₄(aq) + Cu(s); blue colour fades as copper deposits.
Displacement occurs because more reactive metals lose electrons more readily (are better **reducing agents**).
Experimental displacement data can be used to deduce the relative order of reactivity.

Explaining Reactivity (Extended)

Reactivity depends on the tendency of a metal atom to **lose electrons** and form positive ions.
Metals high in the series lose electrons easily and are strong reducing agents.
In displacement, the less reactive metal ion gains electrons (is **reduced**); the more reactive metal loses electrons (is **oxidised**).

Rusting of Iron

**Rusting** is the corrosion of iron requiring both **oxygen** and **water**.
Rust is hydrated iron(III) oxide, a reddish-brown compound.
Equation: iron + water + oxygen → hydrated iron(III) oxide.
Only iron or steel rusts; other metals **corrode**.
Investigating rusting: nail in air+water rusts; nail in boiled water with oil (no air) does not; nail with calcium chloride (no water) does not.

Rust Prevention Methods

**Barrier methods** (grease, oil, paint, plastic) prevent contact with water and oxygen.
If the barrier is scratched, iron is exposed and rusting occurs.
**Sacrificial protection** uses a more reactive metal (e.g., zinc) attached to iron; the more reactive metal corrodes instead.
Zinc bars on steel ships: Zn → Zn²⁺ + 2e⁻; zinc oxidises, iron is protected.
**Galvanising** coats iron with zinc; acts as barrier and provides sacrificial protection if scratched.

Choosing a Protective Metal (Extended)

A metal **above** iron in the reactivity series is suitable for sacrificial protection (e.g., zinc, magnesium).
A metal **below** iron (e.g., copper) is **not** suitable; iron would corrode instead.

States of matter: solid, liquid, gas – particle spacing and arrangement.

Practice questions

Free preview — 8 of 12 questions. Sign up to see them all.

1.Which of the following is the correct order of reactivity for the metals potassium, sodium, calcium, magnesium, aluminium, zinc, iron, copper, silver, gold?
Easy
- APotassium > Sodium > Calcium > Magnesium > Aluminium > Zinc > Iron > Copper > Silver > Gold
- BGold > Silver > Copper > Iron > Zinc > Aluminium > Magnesium > Calcium > Sodium > Potassium
- CPotassium > Sodium > Magnesium > Calcium > Aluminium > Zinc > Iron > Copper > Silver > Gold
- DSodium > Potassium > Calcium > Magnesium > Aluminium > Zinc > Iron > Copper > Silver > Gold
2.State the two conditions necessary for rusting to occur.
Easy
3.Iron can rust in the presence of water alone, without oxygen.
Easy
True or false?
4.Complete the sentence: In the reactivity series, carbon is placed between aluminium and zinc because it is used to extract metals from their oxides.
Medium
In the reactivity series, carbon is placed between $____ and ____$ because it is used to extract metals from their oxides.
5.Match each metal with its reaction with cold water.
Medium
- Potassium
- Sodium
- Calcium
- Magnesium
- Reacts violently
- Reacts quickly
- Reacts less strongly
- Does not react with cold water
6.Write the word equation for the reaction of magnesium with steam.
Medium
7.In an experiment to determine the reactivity of a metal, a student measures the temperature change when the metal reacts with dilute hydrochloric acid. The temperature rises from 20.0°C to 35.0°C. What is the temperature change in °C?
Medium
- A15
- B17
- C14
- D16
8.Which of the following metals will displace copper from copper(II) sulfate solution?
Medium
- ASilver
- BGold
- CZinc
- DCopper

Slides

The Reactivity Series

Metals can be placed in order of reactivity based on their reactions with water and acids.
The most reactive metals are at the top (potassium, sodium) and the least reactive at the bottom (silver, gold).
Carbon and hydrogen are included as non-metals for comparison in extraction and reactions.

Which metal is the most reactive in the reactivity series?

Calcium
Sodium
Potassium
Magnesium

Reactions with Water and Steam

Potassium, sodium, and calcium react with cold water to produce a metal hydroxide and hydrogen gas.
Magnesium reacts very slowly with cold water but vigorously with steam, forming magnesium oxide and hydrogen.
Metals below magnesium in the series do not react with water or steam.

Potassium reacts with cold water to form potassium $____ and ____ gas$ .

Reactions with Dilute Hydrochloric Acid

Metals above hydrogen in the reactivity series react with dilute HCl to produce a salt and hydrogen gas.
The more reactive the metal, the more vigorous the reaction.
Metals below hydrogen (e.g., copper, silver, gold) do not react with dilute HCl.

Which of the following metals does NOT react with dilute hydrochloric acid?

Magnesium
Zinc
Iron
Copper

Displacement Reactions

A more reactive metal can displace a less reactive metal from a solution of its salt.
For example, magnesium displaces copper from copper(II) sulfate solution.
The blue colour of copper sulfate fades as colourless magnesium sulfate forms, and copper metal is deposited.

Which of these are true about displacement reactions?

Zinc can displace iron from iron(II) sulfate.
Copper can displace silver from silver nitrate.
Iron can displace magnesium from magnesium chloride.
Silver can displace copper from copper(II) sulfate.

Rusting of Iron

Rusting is the corrosion of iron, forming hydrated iron(III) oxide (rust).
Both water and oxygen must be present for rusting to occur.
Steel (which contains iron) also rusts under the same conditions.

What two substances are required for iron to rust?

Water and carbon dioxide
Oxygen and carbon dioxide
Water and oxygen
Water and nitrogen

Preventing Rust: Barrier Methods

Coating iron with barriers such as paint, oil, grease, or plastic prevents contact with water and oxygen.
If the coating is scratched or damaged, the iron underneath can rust.
Barrier methods only work as long as the coating remains intact.

Rust is the common name for hydrated ____ oxide.

Sacrificial Protection

A more reactive metal (e.g., zinc) attached to iron will corrode first, protecting the iron.
Zinc loses electrons more easily than iron, so it oxidises instead of iron.
Zinc blocks on steel ships are an example; they must be replaced before they completely corrode.

Which metal is used for sacrificial protection of iron?

Copper
Zinc
Silver
Gold

Galvanising

Galvanising coats iron with a layer of zinc, e.g., by electroplating or dipping in molten zinc.
Zinc forms a protective layer of ZnCO₃ that acts as a barrier.
Even if scratched, the zinc still protects the iron by sacrificial protection.

Which statements about galvanising are true?

Galvanising only works if the coating is intact.
Zinc is more reactive than iron.
Galvanising provides both barrier and sacrificial protection.
Copper can be used to galvanise iron.

Flashcards

What is the order of the reactivity series from most reactive to least reactive?

Potassium, Sodium, Calcium, Magnesium, Aluminium, Carbon, Zinc, Iron, Hydrogen, Copper, Silver, Gold.

What is the mnemonic to remember the reactivity series?

Please send cats, monkeys and cute zebras into hot countries signed Gordon.

Which metals react with cold water?

Potassium, sodium, and calcium react with cold water to form a metal hydroxide and hydrogen gas.

Write the balanced equation for the reaction of potassium with water.

$2K (s) + 2H2O (l)$ → $2KOH (aq) + H2 (g)$

How does magnesium react with steam?

Magnesium reacts with steam to form magnesium oxide and hydrogen gas: Mg $(s) + H2O (g)$ → MgO $(s) + H2 (g)$ .

Which metals react with dilute hydrochloric acid?

Metals above hydrogen in the reactivity series, such as magnesium, zinc, and iron, react with dilute hydrochloric acid to produce a salt and hydrogen.

Write the equation for the reaction of zinc with dilute hydrochloric acid.

Zn $(s) + 2HCl (aq)$ → $ZnCl2 (aq) + H2 (g)$

Why do copper, silver, and gold not react with dilute hydrochloric acid?

They are below hydrogen in the reactivity series, so they do not displace hydrogen from acids.

How can the order of reactivity be deduced experimentally?

By observing the vigour of reactions with water or dilute hydrochloric acid; the more vigorous the reaction, the more reactive the metal.

What happens when magnesium is added to copper(II) sulfate solution?

Magnesium displaces copper: Mg $(s) + CuSO4 (aq)$ → $MgSO4 (aq) + Cu (s)$ . The blue colour fades and copper metal forms.

What is a displacement reaction between a metal and a salt solution?

A more reactive metal displaces a less reactive metal from its salt solution.

What is rusting?

Rusting is the reaction of iron with water and oxygen to form hydrated iron(III) oxide, a reddish-brown compound.

What conditions are necessary for rusting to occur?

Both oxygen and water must be present for iron to rust.

How can you investigate the conditions required for rusting?

Use three test tubes: one with iron nail exposed to air and water, one with boiled water and oil to exclude air, and one with calcium chloride to absorb moisture. Only the nail in the first tube rusts.

What are barrier methods to prevent rust?

Coating iron with grease, oil, paint, or plastic to prevent contact with water and oxygen.

What is sacrificial protection?

Attaching a more reactive metal (e.g., zinc) to iron; the more reactive metal corrodes first, protecting the iron.

Explain why zinc is used for sacrificial protection of steel ships.

Zinc is more reactive than iron, so it loses electrons and oxidises preferentially, preventing the iron from rusting.

What is galvanising?

Coating iron with a layer of zinc, which provides both barrier protection and sacrificial protection if the coating is scratched.

Why is a metal below iron in the reactivity series not suitable for sacrificial protection?

It would not be oxidised instead of iron; iron would still rust because the less reactive metal cannot protect it.

What is the product of rusting?

Hydrated iron(III) oxide (Fe2O3·xH2O).

What is the difference between rusting and corrosion?

Rusting refers specifically to the corrosion of iron or steel; corrosion is the general term for the breakdown of any metal.

What is the word equation for rusting?

iron + water + oxygen → hydrated iron(III) oxide

Unlock all 12 questions, slides, flashcards & more

Create a free account to see every question, the slides, flashcards and revision notes for this topic.

Past papers

Past-paper practice for this topic is coming soon.

🗂️ Coming soon