Air, Water and Everyday Chemistry

50 lessons, pages 401–450.

  1. Air Is a Mixture of Gases — Why air is a mixture, not a compound
  2. Nitrogen: The Main Gas in Air — About 78% of air and why it is so unreactive
  3. Oxygen: The Gas for Life and Burning — About 21% of air, respiration and combustion
  4. Argon and the Other Noble Gases in Air — The unreactive 1% and its uses
  5. Carbon Dioxide in the Atmosphere — A small but vital fraction of air
  6. Water Vapour: The Variable Part of Air — Humidity and why its amount changes
  7. Finding the Proportion of Oxygen in Air — How reacting away oxygen reveals about one-fifth
  8. Layers of the Atmosphere — Troposphere, stratosphere and beyond
  9. Air Has Mass and Exerts Pressure — Particles in motion and atmospheric pressure
  10. Fractional Distillation of Liquid Air — Separating gases by their boiling points
  11. Uses of the Gases from Air — Oxygen in medicine, nitrogen in food packaging, argon in lamps
  12. Testing for Oxygen and Carbon Dioxide — The glowing splint and limewater tests
  13. The Carbon Cycle and Atmospheric Balance — Photosynthesis, respiration and combustion
  14. How Earth's Atmosphere Changed Over Time — From volcanic gases to an oxygen-rich air
  15. Water: Earth's Most Important Compound — Composition, formula and unusual properties
  16. Where Earth's Water Is Found — Oceans, ice, groundwater, lakes and the air
  17. The Water Cycle: An Overview — A continuous loop of physical changes
  18. Evaporation and Transpiration — How water enters the air from seas and plants
  19. Condensation and Cloud Formation — Cooling vapour into droplets
  20. Precipitation: Rain, Snow and Hail — How water returns to the ground
  21. Run-off, Infiltration and Groundwater — Water moving over and through the land
  22. Energy and the Water Cycle — Sunlight, gravity and changes of state
  23. Dissolved Substances in Natural Water — Why rain, river and sea water differ
  24. Chemical Tests for Water — Anhydrous copper(II) sulfate and cobalt chloride paper
  25. Testing the Purity of Water — Boiling point, melting point and evaporating to dryness
  26. Making Water Safe to Drink — Screening, sedimentation, filtration and chlorination
  27. Desalination: Fresh Water from Seawater — Distillation and reverse osmosis compared
  28. What Is Hard Water? — Dissolved calcium and magnesium ions
  29. Where Water Hardness Comes From — Rainwater, carbon dioxide and limestone rocks
  30. Temporary Hardness — Hydrogencarbonate ions that boiling removes
  31. Permanent Hardness — Dissolved sulfates that boiling cannot remove
  32. Hard Water and Soap: Scum Formation — Why soap lathers poorly in hard water
  33. Limescale in Kettles and Pipes — Calcium carbonate deposits and energy waste
  34. Softening Water by Boiling — Removing temporary hardness as a precipitate
  35. Softening Water with Washing Soda — Precipitating calcium and magnesium carbonates
  36. Ion-Exchange Water Softeners — Swapping calcium ions for sodium ions
  37. Comparing the Hardness of Water Samples — Measuring soap needed to form a lasting lather
  38. Benefits and Drawbacks of Hard Water — Taste, health, scale and cleaning costs
  39. What Is Pollution? — Pollutants, sources and harm to living things
  40. Air Pollutants from Burning Fuels — Complete and incomplete combustion products
  41. Carbon Monoxide and Particulates — Invisible poison and soot in the air
  42. Sulfur Dioxide, Nitrogen Oxides and Acid Rain — How acidic gases damage buildings, lakes and trees
  43. The Enhanced Greenhouse Effect — Carbon dioxide, methane and a warming climate
  44. Ozone: Helpful High Up, Harmful Down Low — The ozone layer and ground-level smog
  45. Water Pollution: Sources and Effects — Sewage, industrial waste and oil spills
  46. Fertilisers and Eutrophication — How nutrient run-off starves rivers of oxygen
  47. Plastics and Litter in the Environment — Non-biodegradable waste and microplastics
  48. Reducing Air Pollution — Catalytic converters, cleaner fuels and scrubbers
  49. Everyday Chemistry: Reduce, Reuse, Recycle — Conserving resources and cutting waste at home
  50. Air, Water and Everyday Chemistry: Unit Review — Bringing together air, the water cycle, hardness and pollution