AQA Chemistry Paper 2 Overview

Key Topics

• Topic 6: Rates of Reaction
• Topic 7: Organic Chemistry
• Topic 8: Chemical Analysis
• Topic 9: Chemistry of the Atmosphere
• Topic 10: Using Resources

Topic 6: Rates of Reaction

• Definition: Rate of reaction is the change in quantity of reactant or product over time.
• Mean Rate: Often calculated as the average over the time measured.
• Experiments:
  • Hydrochloric acid and sodium thiosulfate: Solution becomes cloudy indicating reaction progress.
  • Gas syringe method: Measures volume of gas produced.
• Graphing: Quantity on y-axis, time on x-axis. Tangents used to find rate at a specific time.
• Increasing Rate:
  • Higher concentration, pressure, surface area, temperature.
  • Catalysts lower activation energy, not consumed in the reaction.
• Reversible Reactions:
  • Products can revert to reactants.
  • Example: Haber Process.
  • Equilibrium: Rates of forward and reverse reactions equal.
  • Le Chatelier's Principle: System counteracts changes in pressure, concentration, and temperature.

Topic 7: Organic Chemistry

• Crude Oil:
  • Composed mainly of hydrocarbons, specifically alkanes (CnH2n+2).
  • Extracted using fractional distillation.
• Alkanes and Alkenes:
  • Alkanes: Saturated, single bonds.
  • Alkenes: Unsaturated, double bonds, reactive, tested with bromine water.
• Cracking:
  • Breaks long alkanes into shorter alkanes + alkenes.
  • Methods include catalytic and steam cracking.
• Polymers:
  • Made from alkenes through addition polymerization.
  • Types: Polyethene, polypropene, etc.
  • Condensation polymerization involves two monomers, often forms polyesters.
• Alcohols: Organic compounds with OH group, can combust, react with sodium, mix with water.
• Carboxylic Acids: Formed by oxidation of alcohols, represented as COOH.

Topic 8: Chemical Analysis

• Purity and Formulations:
  • Pure substances have specific melting/boiling points.
  • Formulations are mixtures with specific purposes.
• Chromatography:
  • Separates substances in a mixture.
  • Calculation of RF values for identification.
• Chemical Tests:
  • Hydrogen: Squeaky pop with burning splint.
  • Oxygen: Relights glowing splint.
  • Carbon Dioxide: Turns limewater cloudy.
  • Chlorine: Bleaches damp blue litmus paper.
  • Flame tests for metals: Lithium (crimson), Sodium (yellow), Potassium (lilac), etc.

Topic 9: Chemistry of the Atmosphere

• Atmosphere Evolution:
  • Began with nitrogen and carbon dioxide.
  • CO2 dissolved in oceans, reduced by photosynthesis.
  • Greenhouse effect: CO2, water vapor, methane.
• Environmental Impact:
  • Carbon footprint: CO2 emissions from human activities.
  • Pollutants: Carbon monoxide, sulfur dioxide, nitrogen oxides.

Topic 10: Using Resources

• Sustainability:
  • Meeting current needs without compromising future generations.
• Water Treatment:
  • Potable water: Low salt/microbes, not pure.
  • Desalination for saltwater.
• Metal Extraction:
  • Mining, electrolysis, displacement reactions.
  • New methods: Phytomining, bioleaching for copper.
• Lifecycle Assessment (LCA):
  • Evaluates product’s environmental impact.
• Corrosion and Alloys:
  • Corrosion: Chemical breakdown of materials.
  • Alloys: Mixtures of metals, often stronger than pure metals.
• Harbor Process:
  • Production of ammonia for fertilizers, NPK fertilizers.
  • Includes nitrogen, phosphorus, potassium.

Additional Resources

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