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.