Combined Chemistry Paper 2 Revision for AQA Higher Tier

Overview

• Expected topics for Chemistry Paper 2
• Evaluate, explain, and compare questions
• Calculations (20% of the paper)
• Required practicals (15% of the paper)
• Skills: surface area to volume ratio, uncertainty, averages, tables and graphs

Question Types

Evaluate Questions

• Provide advantages, disadvantages, and a justified conclusion
• Typically 4-6 marks

Compare Questions

• Identify similarities and differences

Explain Questions

• Provide detailed scientific explanations

Calculations

• 20% of the exam
• Review equations from Chemistry Paper 1 (Topic C3)
  • Moles = Mass / Mr
  • Concentration = Mass / Volume
  • Concentration = Moles / Volume
  • Volume conversion: cm³ to dm³ by dividing by 1000
  • Uncertainty = Range / 2

Required Practicals

Rate of Reaction

• Factors: temperature, concentration, surface area
• Methods:
  • Gas syringe method (measure gas volume produced over time)
  • Mass loss method (measure mass decrease as gas escapes)
  • Disappearing cross method (time for a precipitate to obscure a mark)

Analysis and Purification of Water

• pH testing with a pH meter
• Test for dissolved solids using evaporation
• Distillation for purifying water

Paper Chromatography

• Separates colored substances
• Stationary phase: chromatography paper
• Mobile phase: solvent
• Calculate Rf value: distance traveled by substance / distance traveled by solvent

Additional Topics

Rate of Reaction Graphs

• Steep gradients indicate faster reactions
• Calculate mean rate of reaction using graphs

Reversible Reactions

• Symbol: ↔
• Example: hydrated copper sulfate ↔ anhydrous copper sulfate + water
• Exothermic and endothermic reactions

Organic Chemistry

• Alkanes: general formula CnH2n+2
• Examples: Methane, Ethane, Propane, Butane
• Complete vs. incomplete combustion

Fractional Distillation

• Separates hydrocarbons by boiling points
• Cracking: converts long hydrocarbons to shorter ones (produces alkanes and alkenes)

Chemical Analysis and Tests

• Hydrogen: lit splint test (squeaky pop)
• Oxygen: relights glowing splint
• Carbon Dioxide: turns limewater cloudy
• Chlorine: bleaches damp litmus paper

Chemistry of the Atmosphere

Evolution of the Atmosphere

• Early atmosphere: volcanic gases, high CO2
• Oceans formed and absorbed CO2
• Photosynthesis increased oxygen levels

Greenhouse Effect

• Sun’s shortwave radiation absorbed and re-radiated as longwave radiation
• Greenhouse gases: CO2, CH4, H2O
• Global warming effects: flooding, extreme weather, etc.

Pollution and Environmental Impact

• Carbon Dioxide: Linked to global warming
• Solid Particulates: Cause global dimming
• Sulfur Dioxide and Nitrogen Oxides: Cause acid rain, respiratory issues
• Carbon Monoxide: Toxic, can kill

Sustainable Development and Resource Use

Life Cycle Assessments

• Evaluate environmental impact from raw material extraction to disposal

Recycling

• Reduces energy usage, conserves resources

Water Treatment and Potable Water

• Filtration and sterilization processes
• Distillation and reverse osmosis in water-scarce regions

Waste Water Treatment

• Screening, sedimentation, aerobic and anaerobic digestion

Advanced Topics (Higher Tier)

Equilibrium and Le Chatelier’s Principle

• System changes counteract disturbances in temperature, pressure, concentration

Phytomining and Bioleaching

• Extraction of metals using plants and bacteria respectively

These notes cover key points from the lecture on Chemistry Paper 2 expectations for AQA higher tier students, focusing on practical skills, calculations, and various chemistry topics.