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Acid-Base Chemistry

Use ions and reaction patterns to explain acids, bases and salts.

O-Level 6092 (2026) / SEC G3 K324 (2027)

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7 topics

  1. Acids, alkalis and pH

    Read acidity as an ion balance, not just a colour.

  2. Recognise the reaction pattern

    Predict the salt and the other products.

  3. Classify an oxide by its reactions

    Metal/non-metal character suggests a pattern, but exceptions matter.

  4. Strong and weak is different from concentrated and dilute

    Separate extent of ionisation from amount per unit volume.

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  5. Use solubility rules to choose starting materials

    An insoluble product can be separated as a precipitate.

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  6. Prepare and purify the salt you want

    The method follows the solubility of both product and reactants.

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  7. Ammonia: choose useful industrial conditions

    Reversible reactions require a balance between yield, speed and cost.

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Scope and references

Learning outcomes and sources

5. Acid-Base Chemistry (6092 / K324). Use the outcome map to find the explanation for a particular syllabus requirement.

See the learning outcome map

  1. 5.1(a) Define acids and alkalis

    • Aqueous H+ and OH-
    • Universal Indicator

    Acids, alkalis and pH

  2. 5.1(b) Compare acidity and alkalinity

    • Relative ion concentrations
    • Indicator colours
    • pH scale, no logarithmic calculation

    Acids, alkalis and pH

  3. 5.1(c) Distinguish strong and weak acids

    • Extent of ionisation
    • Distinguish concentration

    Strong and weak is different from concentrated and dilute

  4. 5.1(d) Describe acid reaction patterns

    • Metals, bases and carbonates
    • Salt products

    Recognise the reaction pattern

  5. 5.1(e) Explain neutralisation

    • H+ + OH- -> water

    Recognise the reaction pattern

  6. 5.1(f) Explain control of soil acidity

    • Importance of soil pH
    • Calcium hydroxide treatment

    Acids, alkalis and pH

  7. 5.1(g) Describe base reactions

    • With acids
    • With ammonium salts on warming

    Recognise the reaction pattern

  8. 5.1(h) Classify oxides

    • Acidic, basic, amphoteric, neutral
    • Metal/non-metal character and exceptions

    Classify an oxide by its reactions

  9. 5.2(a) Prepare, separate and purify salts

    • Precipitation
    • Titration
    • Acids with metals, insoluble bases and insoluble carbonates

    Prepare and purify the salt you want

  10. 5.2(b) Apply salt-solubility rules

    • Nitrates
    • Chlorides including silver and lead
    • Sulfates including barium, calcium and lead
    • Carbonates and hydroxides
    • Group 1 and ammonium salts

    Use solubility rules to choose starting materials

  11. 5.2(c) Select a salt-preparation route

    • Suitable starting materials
    • Product and reactant solubility

    Use solubility rules to choose starting materialsPrepare and purify the salt you want

  12. 5.3(a) Identify ammonia feedstocks

    • Nitrogen from air
    • Hydrogen from cracking crude-oil hydrocarbons

    Ammonia: choose useful industrial conditions

  13. 5.3(b) Recognize reversibility

    • Ammonia synthesis and decomposition

    Ammonia: choose useful industrial conditions

  14. 5.3(c) Interpret industrial process data

    • Haber temperature, pressure, rate/yield/cost
    • No Le Chatelier requirement

    Ammonia: choose useful industrial conditions