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Oak National Academy
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New
New
Year 10
OCR
Higher

Describing salts

I can describe salts and work out their empirical chemical formulae from diagrams, as well as give ionic descriptions of acids and alkalis.

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New
New
Year 10
OCR
Higher

Describing salts

I can describe salts and work out their empirical chemical formulae from diagrams, as well as give ionic descriptions of acids and alkalis.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. A salt is formed when an acid neutralises a base.
  2. Salts are giant, 3D ionic structures that form crystals with regular arrangements of ions.
  3. The empirical chemical formula of a salt provides the ratio of metal to non-metal ions it contains.
  4. Acids contain aqueous hydrogen ions, H⁺(aq) and alkalis contain aqueous hydroxide ions, OH⁻(aq).
  5. During a neutralisation reaction: H⁺(aq) + OH⁻(aq) → H₂O(l).

Common misconception

Pupils regularly think that neutralisation produces a neutral (i.e. pH 7) solution.

Stress that neutralisation occurs from a complete reaction between an acid and base, which usually occurs between strong acids and strong bases. If a weak acid or weak base is used, the salt solution produced may be alkaline or acidic respectively.

Keywords

  • Salt - An ionic compound formed from positive and negative ions electrostatically attracted to each other.

  • Empirical formula - Shows the simplest whole number ratio of atoms of each element in a compound.

  • Acid - A solution that has a pH of less than 7.

  • Base - Reacts with an acid to form a salt.

  • Neutralisation - A chemical reaction between an acid and base, producing a solution of a metal salt and water.

Create (~4-6) sample groups consisting of a base, acid and relevant salt. Each sample is labelled with the chemical formula only. Pupils identify the base, acid and salt in each sample group (i.e. in a table). Challenge pupils to justify their classification; extend pupils to identify any trends.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.
Match the name of the acid to its correct chemical formula.
Correct Answer:Hydrochloric acid,HCl

HCl

Correct Answer:Sulfuric acid,H₂SO₄

H₂SO₄

Correct Answer:Nitric acid,HNO₃

HNO₃

Q2.
Pair each of the following terms with one of the statements
Correct Answer:Acidic,pH 6

pH 6

Correct Answer:Basic,pH 8

pH 8

Correct Answer:Alkali,a soluble base

a soluble base

Correct Answer:Corrosive,cause chemical burns to skin

cause chemical burns to skin

Q3.
What is the definition of an acid?
Correct answer: A solution that has a pH of less than 7.
A solution that has a pH of more than 7.
A solution that is neutral.
Q4.
What happens during neutralisation?
A base reacts with another base to form a new element.
Correct answer: An acid reacts with a base to form a salt and water.
An acid reacts with an acid to form a gas.
Q5.
Which ion is common in alkaline solutions?
Hydrogen ion (H⁺)
Correct answer: Hydroxide ion (OH⁻)
Sodium ion (Na⁺)
Q6.
Which ion is common in acidic solutions?
Correct answer: Hydrogen ion (H⁺)
Hydroxide ion (OH⁻)
Sodium ion (Na⁺)

Exit quiz

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6 Questions

Q1.
What happens during a neutralisation reaction?
A base reacts with a base to form a salt.
Correct answer: An acid reacts with a base to form a salt and water.
An acid reacts with an acid to form a salt.
Q2.
What is a base?
A substance that forms a gas when it reacts.
A substance that has a pH less than 7.
Correct answer: A substance that reacts with an acid to form a salt.
Q3.
When can salts conduct electricity?
Only when in powder form.
Only when solid.
Correct answer: When dissolved in water or molten.
Q4.
Which of the following best describes the structure of a salt?
Correct answer: A giant, 3D ionic lattice.
A metallic lattice.
A simple molecular structure.
Q5.
What is the significance of the empirical formula of a salt?
It indicates the colour of the salt.
Correct answer: It provides the ratio of metal to non-metal ions.
It shows how the ions are arranged in the lattice.
Q6.
What happens to the ions in a salt when it dissolves in water?
The ions form a gas.
The ions react with water to form a new compound.
Correct answer: The ions separate and disperse throughout the solution.