Making Salts from Acids
Salts: naming and making them
This GCSE chemistry lesson explores Making Salts from Acids. Students learn how acids react with metals, bases, alkalis and carbonates, and select practical methods for preparing pure, dry soluble salts. It supports KS4 classroom teaching, independent study and exam revision using clear, subject-specific vocabulary.
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Salts: naming and making them
This GCSE chemistry lesson explores Making Salts from Acids. Students learn how acids react with metals, bases, alkalis and carbonates, and select practical methods for preparing pure, dry soluble salts. It supports KS4 classroom teaching, independent study and exam revision using clear, subject-specific vocabulary.
Salts, KS4 Chemistry, GCSE Chemistry, Soluble Salts, Insoluble Salts, Salt Preparation, Acid Reactions, Crystallisation, Precipitation, Metal Carbonates, Metal Hydroxides, Neutralisation, Titration, Solubility Rules, MCQs, Open Questions, Polls, Emoji Polls, Exit Tickets
Learning goal
I can explain what salts are, how they are named, and how they are made by neutralisation and related reactions.
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What are some words you associate with what salt actually is?
Use this to surface everyday ideas such as table salt alongside chemistry ideas such as ions, crystals, acids or reactions. Pick up the misconception that salt only means sodium chloride.
What is a salt?
A salt is an ionic compound formed when the hydrogen ion in an acid is replaced by a metal ion or an ammonium ion.
Examples:
sodium chloride, NaCl
copper sulfate, CuSO₄
ammonium nitrate, NH₄NO₃
Stress that 'salt' does not mean only sodium chloride. Link to ions: positive ion from a metal or ammonium, negative ion from the acid.
Where does the salt name come from?
The first part of the name comes from the positive ion.
The second part comes from the acid.
So the acid used helps decide the ending of the salt name.
This is the naming rule students will apply repeatedly. Keep the wording consistent: positive ion first, acid ending second.
Acids and salt endings
gives chlorides
gives sulfates
gives nitrates
Salt ending
hydrochloric acid
sulfuric acid
nitric acid
Acid
Students often misspell sulfate; keep the UK spelling shown throughout. You can mention that the anions are chloride, sulfate and nitrate.
Naming common salts
sodium chloride comes from hydrochloric acid
copper sulfate comes from sulfuric acid
ammonium nitrate comes from nitric acid
magnesium chloride is a chloride because it comes from hydrochloric acid
calcium nitrate is a nitrate because it comes from nitric acid
Check that students can identify both parts of each name: the cation and the acid-derived ending.
Neutralisation and related reactions
Many salts are made when an acid reacts and its hydrogen ion is replaced.
Common preparation routes are:
acid + metal
acid + base or alkali
acid + carbonate
acid + metal oxide
Use 'neutralisation and related reactions' as the umbrella idea. Strictly, acid + metal is not neutralisation, but it still forms salts and fits the lesson goal.
Which statement best defines a salt?
An ionic compound from acid replacement
Any solid that dissolves in water
A metal mixed with an acid
A base that reacts with water
Checks the precise definition from slides 2–6. Distractors target common confusions between salts, soluble substances and reactants.
Build the naming rule
The first part of a salt name comes from the positive ion. The second part comes from the acid used. Hydrochloric acid makes chlorides, sulfuric acid makes sulfates, and nitric acid makes nitrates.
All blanks are load-bearing naming terms from slides 3–5.
Acid + metal
This reaction makes:
salt
hydrogen
General pattern:
acid + metal → salt + hydrogen
Remind students that only metals above hydrogen in the reactivity series react this way in simple school examples.
Example: making a chloride with a metal
Word equation
magnesium + hydrochloric acid → magnesium chloride + hydrogen
Symbol equation
Mg + 2HCl → MgCl₂ + H₂
Use this to model balancing: two HCl are needed to supply two chloride ions and make H2.
Acid + base or alkali
A base neutralises an acid.
If the base is soluble in water, it is called an alkali.
General pattern:
acid + base/alkali → salt + water
Students often confuse base and alkali. Keep it simple: all alkalis are bases, but not all bases are alkalis.
Example: sodium chloride by neutralisation
Word equation
sodium hydroxide + hydrochloric acid → sodium chloride + water
Symbol equation
NaOH + HCl → NaCl + H₂O
This is a clean 1:1 neutralisation example. Emphasise that sodium chloride is a salt even though students know it as table salt.
Acid + carbonate
Carbonates react with acids to make:
salt
water
carbon dioxide
General pattern:
acid + carbonate → salt + water + carbon dioxide
Point out the gas test if useful verbally: carbon dioxide turns limewater milky. Do not add extra practical detail to the slide.
Example: making copper sulfate
Word equation
copper carbonate + sulfuric acid → copper sulfate + water + carbon dioxide
Symbol equation
CuCO₃ + H₂SO₄ → CuSO₄ + H₂O + CO₂
This example reinforces sulfate naming from sulfuric acid and introduces a common blue salt students may recognise.
Acid + metal oxide
Metal oxides are bases.
They react with acids to form:
salt
water
General pattern:
acid + metal oxide → salt + water
This links metal oxides to neutralisation clearly. Keep the distinction from alkalis: metal oxides are usually insoluble bases.
Example: making copper sulfate
Word equation
copper oxide + sulfuric acid → copper sulfate + water
Symbol equation
CuO + H₂SO₄ → CuSO₄ + H₂O
Useful contrast with the carbonate example: same salt formed, but no carbon dioxide because there is no carbonate ion.
What are the products of acid + carbonate?
Salt and hydrogen
Salt and water
Salt, water and carbon dioxide
Salt and carbon dioxide
Checks that students distinguish carbonate reactions from metal and oxide reactions.
Compare the reaction patterns
When an acid reacts with a metal, the products are a salt and hydrogen. When an acid reacts with a base or alkali, the products are a salt and water. When an acid reacts with a carbonate, carbon dioxide is also formed.
A compact comparison across slides 7–14. 'Oxide' is included as a plausible distractor because metal oxides also form salt and water.
Why does only one copper sulfate method make carbon dioxide?
Expected elements: students should explain that copper carbonate makes copper sulfate, water and carbon dioxide, but copper oxide makes copper sulfate and water only. The key reasoning is that carbonate reactions release carbon dioxide whereas oxide reactions do not.
Soluble and insoluble salts
A soluble salt dissolves in water.
An insoluble salt does not dissolve much in water.
This matters because the method used to prepare a salt depends on whether the salt is soluble or insoluble.
Do not overload with full solubility rules here. The lesson goal only requires the idea and the link to preparation choice.
Making a soluble salt
To make a soluble salt, use an acid with:
a metal
an insoluble base
a carbonate
a metal oxide
Then the salt can be obtained from the solution by crystallisation.
At this level, the key rule is that a soluble salt can be made by reacting acid with a suitable solid, often added in excess, then filtering and crystallising.
Making a soluble salt from an alkali
If both reactants are solutions, such as an acid and an alkali, the excess method will not work.
Instead, the acid and alkali must be mixed in the correct amounts so only salt and water remain.
This is the key selection rule for sodium, potassium and ammonium salts. You may mention indicator or titration verbally, but keep it off the slide unless needed.
Example: ammonium nitrate
Word equation
ammonia + nitric acid → ammonium nitrate
Ammonia in water acts as an alkali, so this reaction makes a soluble salt by careful neutralisation.
If helpful, mention that ammonium salts contain NH4+ instead of a metal ion. Avoid introducing unnecessary detail about fertilisers unless time allows.
Making an insoluble salt
An insoluble salt is usually made by precipitation.
Two soluble solutions are mixed together.
Their ions swap partners, and an insoluble salt forms as a solid precipitate.
Use particle language: ions in solution combine to make a solid lattice. No need to teach full ionic equations unless the class is ready.
Precipitation example
Word equation
silver nitrate + sodium chloride → silver chloride + sodium nitrate
Symbol equation
AgNO₃ + NaCl → AgCl + NaNO₃
Here, silver chloride is the insoluble precipitate.
This slide gives a clear precipitation example even though it is not one of the three named acids. It supports the required idea of insoluble salts and precipitation.
Choosing the right method
Want a soluble salt from an insoluble solid? Use acid + metal oxide, acid + carbonate, or another suitable base.
Want a soluble sodium, potassium or ammonium salt? Use acid + alkali.
Want an insoluble salt? Use precipitation from two soluble solutions.
This is the decision slide that resolves the practical side of the central question. Keep it as rules of thumb, not a complete decision tree.
Word and symbol equations
When writing equations for salt preparation:
identify the acid and its salt ending
identify the positive ion in the salt
add the other products, such as water, hydrogen or carbon dioxide
balance the symbol equation so atoms match on both sides
Students often forget extra products. Encourage them to start with the reaction pattern before writing formulae.
How is an insoluble salt usually prepared?
Acid with a metal
Acid with an alkali
Crystallisation only
Precipitation
Checks the key method choice from slides 15–21.
Choose the right method
A soluble salt can be obtained from solution by crystallisation. If both reactants are solutions, such as an acid and an alkali, they must be mixed in the correct amounts. An insoluble salt is usually made by precipitation.
Summarises the preparation-choice rules from slides 15–21 using the same lesson wording.
Which symbol equation is balanced?
Mg + HCl → MgCl2 + H2
Mg + 2HCl → MgCl2 + H2
Mg + 2HCl → MgCl + H2
2Mg + HCl → 2MgCl2 + H2
Uses the magnesium + hydrochloric acid example from slide 8 and checks balancing as well as formula accuracy.
Do you feel as though your confidence for making salts has improved from this lesson?
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Glossary
salt - an ionic compound formed when the hydrogen ion in an acid is replaced by a metal ion or an ammonium ion
neutralisation - a reaction in which an acid reacts with a base to form salt and water
base - a substance that neutralises an acid
alkali - a base that dissolves in water
soluble - able to dissolve in water
insoluble - not able to dissolve much in water
precipitate - an insoluble solid formed in a reaction
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Glossary
chloride - a salt made from hydrochloric acid
sulfate - a salt made from sulfuric acid
nitrate - a salt made from nitric acid
carbonate - a compound containing the CO₃²⁻ ion that reacts with acids to release carbon dioxide
metal oxide - a basic compound of a metal and oxygen
ammonium ion - the positive ion NH₄⁺ found in ammonium salts
crystallisation - forming solid crystals from a salt solution
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