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Year 10
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Higher

Solubility rules

I can remember, and apply, the solubility rules to know whether a salt formed is soluble or insoluble.

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New
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Year 10
OCR
Higher

Solubility rules

I can remember, and apply, the solubility rules to know whether a salt formed is soluble or insoluble.

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Lesson details

Key learning points

  1. There are a list of general rules which describe the solubility of common types of substances in water.
  2. Reactions that form insoluble products are called precipitation reactions; the solids formed are called the precipitate.
  3. When two soluble salts are mixed together, sometimes they will rearrange to create an insoluble salt.
  4. Solubility rules can be used to identify which two solutions are needed to mix in order to create an insoluble salt.

Keywords

  • Solubility - The ability of a substance to dissolve in a particular solvent creating a solution; how well a solute dissolves in a solvent.

  • Salt - An ionic compound, usually formed by neutralisation of an acid by a base.

  • Soluble - When a substance dissolves in a liquid, it is described as soluble in that liquid.

  • Precipitate - An insoluble solid formed when two solutions react together.

  • Insoluble - When a substance does not dissolve in a liquid, it is described as insoluble in that liquid.

Common misconception

All salts are either completely soluble or completely insoluble in water.

Not all salts follow a strict 'soluble' or 'insoluble' rule. Some salts have limited solubility, meaning they dissolve only to a certain extent. Solubility rules help us predict the solubility of common salts, but there are always exceptions.

Emphasise solubility rules in predicting the outcomes of reactions. Encourage students to refer to solubility tables and charts when planning experiments involving salts. Provide plenty of practice with predicting the products of precipitation reactions and writing equations.
Teacher tip

Equipment

Solutions of: AgNO₃, NaCl, BaCl₂, FeCl₂, NaOH, Na₂SO₄, H₂SO₄. CaCO₃ powder, test tubes.

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

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).

Lesson video

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Starter quiz

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6 Questions

Q1.
What is an ionic compound?
A substance made of molecules with covalent bonds.
Correct answer: A substance composed of positively and negatively charged ions.
A type of metal that is highly conductive.
A compound formed by sharing electrons equally.
Q2.
What is solubility?
Correct answer: The ability of a substance to dissolve in a solvent.
The ability of a substance to conduct electricity.
The measure of a substance's density.
The temperature at which a substance melts.
Q3.
What does the periodic table display?
The properties of chemical reactions.
Correct answer: An arrangement of elements by their atomic number.
The states of matter of various substances.
The list of all known compounds.
Q4.
What is a chemical reaction?
A change in state from solid to liquid.
A change in colour without forming new substances.
Correct answer: A process where substances combine or break apart to form new substances.
A physical change in the shape of an object.
Q5.
What are physical properties?
Characteristics observed during a chemical reaction.
Properties that only appear in solution.
Traits that describe the reactivity of a substance.
Correct answer: Features of a substance that can be measured.
Q6.
What is a mixture?
A substance with a fixed composition that can't be separated into its components
Correct answer: A combination of two or more substances that are not chemically bonded.
A type of chemical reaction producing a new substance.
A single pure substance with uniform properties.

Exit quiz

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6 Questions

Q1.
What is solubility?
Correct answer: The ability of a substance to dissolve in a solvent.
The speed at which a substance dissolves.
The ability of a substance to conduct electricity.
The temperature at which a substance melts.
Q2.
What is a precipitate?
A gas that dissolves in water.
A substance that evaporates from a liquid.
Correct answer: A solid that forms and settles out of a liquid mixture.
A chemical that accelerates a reaction.
Q3.
Which ionic compounds are generally soluble?
All compounds containing metals.
Correct answer: Most chlorides, sulfates, and nitrates.
Most oxides, hydroxides, and carbonates.
All ionic compounds are soluble
Q4.
What is an exception to the solubility of chlorides?
sodium chloride
Correct answer: lead (II) chloride
potassium chloride
ammonium chloride
Q5.
What is a precipitation reaction?
A reaction where a gas is formed.
Correct answer: A reaction where two soluble salts form an insoluble solid.
A reaction where two liquids combine to form water.
A reaction where energy is released as light.
Q6.
How can solubility rules help in predicting reactions?
They help predict the speed of reactions.
Correct answer: They help predict which compounds will dissolve or form a precipitate.
They help predict whether a gas will be formed.
They help determine the energy released in a reaction.