F4 Topic Checklist Metals and Metal Extraction 2025

Page 1: Metal Extraction and Rust Prevention

  • Rust Formation:

    • Conditions for Rusting:

      • Iron and steel rust to form hydrated iron(III) oxide.

  • Barrier Methods of Rust Prevention:

    • Common methods include:

      • Painting

      • Greasing

      • Coating with plastic

  • Mechanism of Barrier Methods:

    • Prevent rusting by excluding oxygen or water from contact with the metal.

  • Galvanisation:

    • Involves using zinc to prevent rusting.

    • Functions as both a barrier method and sacrificial protection.

  • Sacrificial Protection:

    • Based on the reactivity series: more reactive metals will corrode first, thus protecting less reactive metals.

    • Involves electron loss from the sacrificial metal instead of the metal being protected.

  • Metal Extraction:

    • Reactivity Series:

      • The ease of extracting metals from ores depends on their position in the reactivity series.

  • Extraction of Iron from Hematite:

    • Process involves the following steps:

      • Burning carbon (coke) to provide heat, forming carbon dioxide.

      • Reducing carbon dioxide to carbon monoxide.

      • Reducing iron(III) oxide by carbon.

      • Thermal decomposition of calcium carbonate (limestone) to produce calcium oxide.

      • Formation of slag as a byproduct.

  • Ore of Aluminium:

    • Main ore is bauxite, extracted primarily through electrolysis.

  • Symbol Equations for Extraction of Iron from Hematite:

    1. C + O2 → CO2

    2. C + CO2 → 2CO

    3. Fe2O3 + 3CO → 2Fe + 3CO2

    4. CaCO3 → CaO + CO2

    5. CaO + SiO2 → CaSiO3

Page 2: Stoichiometry

  • Relative Atomic Mass (Ar):

    • Defined as the average mass of an element's isotopes compared to 1/12th the mass of a 12C atom.

  • Relative Molecular Mass (Mr):

    • Defined as the total of the relative atomic masses in a compound.

  • Mole Concept:

    • One mole of any substance contains 6.02 × 10²³ particles (Avogadro's constant).

    • Relationship: amount of substance (mol) = mass (g) ÷ molar mass (g/mol).

  • Calculations:

    • Determine amount of substance, mass, molar mass, and number of particles using Avogadro's number.

    • Compute percentage yield, composition by mass, and purity using given data.

  • Empirical and Molecular Formulas:

    • Empirical formula is the simplest whole number ratio of elements.

    • Molecular formula indicates the number and type of atoms in a molecule.

    • Ability to calculate empirical and molecular formulas from data.

  • Water of Crystallisation:

    • Defined as water molecules that are chemically combined in hydrated crystals.

  • Definitions:

    • Hydrated Substance: Chemically combined with water.

    • Anhydrous Substance: Contains no water.

Page 3: Additional Stoichiometry Concepts

  • Hydrated Salts:

    • Ability to deduce the value of x in a hydrated salt formula.

  • Molar Gas Volume:

    • Use the molar gas volume of 24 dm³ at room temperature and pressure in gas calculations.

  • Stoichiometric Calculations:

    • Ability to calculate reacting masses, identifying limiting reactants and calculating volumes of gases at r.t.p.

    • The formula for volume of gas:

      • v = n x 24 dm³ (where n is the number of moles).

      • v = n x 24,000 cm³.

  • Percentage Calculations:

    • Calculate percentage yields and compositions based on reaction data.