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4CH1

Acids, Bases and Salt Preparations

Inorganic Chemistry · 0 question types

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4CH1 Topics

Group 1: The Alkali Metals5%
Group 7: The Halogens6%
Gases in the Atmosphere5%
The Reactivity Series6%
Extraction and Uses of Metals6%
Acids, Alkalis and Titrations10%
Acids, Bases and Salt Preparations8%
  1. Solubility Rules for Ionic Compounds
  2. Acids and Bases as Proton Donors and Acceptors
  3. Reactions of Acids
  4. Preparing Soluble Salts
  5. Preparing Insoluble Salts by Precipitation
  6. Required Practical Preparations
Chemical Tests8%

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Past paper frequency (2018 to 2024)

This topic accounts for approximately 8% of your exam marks.

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Stable8%

Soluble and insoluble salt preparation methods are consistently tested with multi-step answers.

Why solubility matters

  • Knowing which salts dissolve in water and which do not decides which preparation method to use
  • A soluble salt is built up in solution first and then crystallised out by evaporation
  • An insoluble salt is dropped out of solution by precipitation — mixing two soluble salts whose ions exchange to form the wanted insoluble product

Solubility patterns to memorise

Type of saltSoluble in waterInsoluble exceptions
Sodium, potassium and ammonium saltsAll—
NitratesAll—
ChloridesMostSilver chloride, lead(II) chloride
SulfatesMostBarium sulfate, calcium sulfate, lead(II) sulfate
CarbonatesSodium, potassium and ammonium carbonates onlyThe rest are insoluble
HydroxidesSodium, potassium and ammonium hydroxides; calcium hydroxide is sparingly soluble (limewater)Most other metal hydroxides
  • Calcium hydroxide solution is what you know as limewater, used as the test for carbon dioxide

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Acid–alkali Titrations

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Acids and Bases as Proton Donors and Acceptors