Electrolysis and Chemical Tests Revision List

Electrolysis and Chemical Tests Revision List

Electrolysis Understanding

  • Covalent Compounds:

    • Do not conduct electricity due to lack of free-moving charged particles.

  • Ionic Compounds:

    • Conduct electricity only when they are molten or dissolved in water (aqueous solution) because ions are free to move.

  • Ions:

    • Anion: Negatively charged ion.

    • Cation: Positively charged ion.

Experiments in Electrolysis

  • Electrolysis Experiments:

    • Molten Compounds:

      • Example: Lead(II) bromide.

    • Aqueous Solutions:

      • Example: Sodium chloride, dilute sulfuric acid, copper(II) sulfate.

    • Prediction of Products:

      • Predict the expected products of electrolysis for each compound.

  • Ionic Half-equations:

    • Write and represent reactions occurring at electrodes during electrolysis.

    • Classify these reactions as oxidation or reduction.

Practical Investigations

  • Electrolysis of Aqueous Solutions:

    • Conduct practical experiments to explore electrolysis with specified aqueous solutions.

Testing for Gases and Ions

Gas Volume Calculations

  • Understand calculations involving gas volumes.

  • Molar volume of a gas at room temperature and pressure is:

    • 24 dm³ (or 24,000 cm³).

Solubility Curves

  • Plot and Interpret:

    • Ability to plot and interpret solubility curves for solids in water.

  • Investigate Solubility:

    • Practical investigation of a solid's solubility in water at specific temperatures.

Predicting Solubility of Ionic Compounds

  • General Rules for Solubility:

    • Common sodium, potassium, and ammonium compounds are soluble.

    • All nitrates are soluble.

    • Common chlorides are soluble except silver and lead(II).

    • Common sulfates are soluble except for barium, calcium, and lead(II).

    • Common carbonates are typically insoluble, except sodium, potassium, and ammonium.

    • Common hydroxides are generally insoluble except sodium, potassium, and calcium (with calcium hydroxide being slightly soluble).

Gas Tests

  • Tests for Gases:

    • Hydrogen: Conduct test to identify.

    • Oxygen: Conduct test to identify.

    • Carbon Dioxide: Conduct test to identify.

    • Ammonia: Conduct test to identify.

    • Chlorine: Conduct test to identify.

  • Flame Test:

    • Procedure to carry out flame tests for cations.

  • Flame Test Colors for Cations:

    • Li+: Red

    • Na+: Yellow

    • K+: Lilac

    • Ca2+: Orange-red

    • Cu2+: Blue-green.

Anion Tests

  • Tests for Anions:

    • Cl–, Br–, and I–: Use acidified silver nitrate solution.

    • SO42–: Use acidified barium chloride solution.

    • CO32–: Use hydrochloric acid and identify the gas evolved.

Water Testing

  • Presence of Water:

    • Test using anhydrous copper(II) sulfate.

  • Purity of Water:

    • Conduct physical test to determine if a water sample is pure.