4CH1

Acids, Bases and Salt Preparations

Inorganic Chemistry

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

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

stable
Low
Stable8%

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

Acid + metal → salt + hydrogen

  • Only a metal above hydrogen in the reactivity series reacts with a dilute acid (see topic 13 section 1)
  • General reaction:

metal + acid → salt + hydrogen

  • Test for the gas: a lit splint at the mouth of the tube gives the squeaky pop of hydrogen
  • Examples (using a +2 metal):
    • Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g)
    • Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g)
  • Acid → salt naming rule:
    • Hydrochloric acid gives a chloride
    • Sulfuric acid gives a sulfate
    • Nitric acid gives a nitrate

Acid + base → salt + water

  • Reacting any acid with a base is a and always gives the same two products: a salt plus water

acid + base → salt + water

Acid + baseEquation
HCl + NaOHNaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
H2SO4 + CuOCuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l)
HNO3 + ZnOZnO(s) + 2 HNO3(aq) → Zn(NO3)2(aq) + H2O(l)

Acid + metal carbonate → salt + carbon dioxide + water

  • Acids react with metal carbonates to give three products: a salt, carbon dioxide gas, and water

acid + metal carbonate → salt + carbon dioxide + water

  • A distinguishing feature is the as carbon dioxide is released — passing the gas through limewater turns it milky, confirming CO2
  • Examples:
    • CuCO3(s) + 2 HCl(aq) → CuCl2(aq) + CO2(g) + H2O(l)
    • ZnCO3(s) + H2SO4(aq) → ZnSO4(aq) + CO2(g) + H2O(l)
    • Na2CO3(s) + 2 HNO3(aq) → 2 NaNO3(aq) + CO2(g) + H2O(l)