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Year 11
OCR
Foundation

Ionic equations: aqueous ion tests

I can write balanced ionic equations for the identification of cations and anions in aqueous solutions.

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New
New
Year 11
OCR
Foundation

Ionic equations: aqueous ion tests

I can write balanced ionic equations for the identification of cations and anions in aqueous solutions.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. An ionic equation represents the reaction between positive and negative ions.
  2. The electric charge on each side of an ionic equation adds up to zero.
  3. (s), (l), (g) and (aq) in ionic equations identify the state of each substance as solid, liquid, gas or in solution

Common misconception

All ionic compounds dissociate completely in aqueous solutions.

Not all ionic compounds dissociate completely in water; some may not dissolve at all. It's important to know the solubility rules to correctly predict the behaviour of compounds in solution.

Keywords

  • Ion - A charged particle formed when an atom or molecule gains or loses electrons.

  • Ionic equation - An equation that shows only the ions and molecules directly involved in a chemical reaction, excluding spectator ions.

  • Spectator ion - An ion that remains unchanged during a chemical reaction and does not participate in the formation of the product.

  • Chemical species - Any chemical entity, such as atoms, ions, or molecules involved in a chemical process.

  • False positive - An incorrect test result indicating the presence of a substance or condition that is actually absent.

Focus on the importance of correctly identifying and removing spectator ions, balancing charges, and choosing appropriate reagents to avoid false positives. Use varied examples to reinforce these concepts.
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.
What is required for an atom to become an ion?
Change in atomic mass.
Correct answer: Loss or gain of electrons.
Loss or gain of protons.
Q2.
What is the charge on a cation?
Negative
Neutral
Correct answer: Positive
Q3.
What happens to ionic compounds when they dissolve in water?
Correct answer: They dissociate into their constituent ions.
They form atoms.
They remain as molecules.
Q4.
How do you balance a chemical equation?
Correct answer: Ensure the same number of each type of atom on both sides.
Equal charges on both sides.
Equal masses on both sides.
Q5.
What is the charge on a chloride ion?
Correct answer: Negative
Neutral
Positive
Q6.
Which of the following is a common cation?
Correct answer: Ca²⁺
Cl⁻
SO₄²⁻

Exit quiz

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6 Questions

Q1.
What is a spectator ion?
Correct answer: An ion that does not participate in the chemical reaction and remains unchanged.
An ion that forms a precipitate.
An ion that participates in the reaction and changes.
Q2.
What must be conserved in a balanced ionic equation?
Correct answer: Mass and charge
Temperature and concentration
Volume and pressure
Q3.
What is the first step in writing an ionic equation?
Balance the equation.
Identify spectator ions.
Correct answer: Write the molecular equation.
Q4.
What is the net ionic equation for the reaction: BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + NaCl(aq)
Ba²⁺(aq) + 2Na⁺(aq) → BaNa₂(aq)
Correct answer: Ba²⁺(aq) + SO₄²⁻(aq) → BaSO₄(s)
BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)
Q5.
What is the net ionic equation for the reaction: AgNO₃(aq) + NaCl(aq) → AgCl(s) + NaNO₃(aq)
Correct answer: Ag⁺(aq) + Cl⁻(aq) → AgCl(s)
Ag⁺(aq) + NO₃⁻(aq) → AgNO₃(s)
2AgNO₃(aq) + 2NaCl(aq) → 2AgCl(s) + 2NaNO₃(aq)
Q6.
What must be included when balancing ionic equations?
Catalysts
Correct answer: State symbols (s, l, g, aq)
Temperatures