Acids, Bases and Salts

50 lessons, pages 771–820.

  1. Acids, Bases and Salts: Unit Overview — From indicators to ions, the pH scale, neutralisation and salts
  2. Acids as Sources of Hydrogen Ions — H⁺ ions in aqueous solution and the hydronium ion
  3. Alkalis as Sources of Hydroxide Ions — OH⁻ ions in solution; bases versus alkalis
  4. Why Water Is Needed for Acidity — Dry acids, ionisation in water and conductivity
  5. The pH Scale Revisited — pH 0 to 14, neutral point and measuring acidity quantitatively
  6. pH and Hydrogen Ion Concentration — Each pH unit is a tenfold change in H⁺ concentration
  7. Measuring pH with Universal Indicator and pH Meters — Colour charts, probes, calibration and precision
  8. Strong and Weak Acids — Complete versus partial ionisation; reversible arrows
  9. Strong and Weak Alkalis — Sodium hydroxide versus aqueous ammonia
  10. Strength Versus Concentration — Why a dilute strong acid differs from a concentrated weak acid
  11. Dilution and pH Change — How adding water shifts pH towards 7
  12. Common Acids and Their Formulae — HCl, H₂SO₄, HNO₃, CH₃COOH and the ions they release
  13. Common Bases and Their Formulae — Metal oxides, hydroxides, carbonates and ammonia
  14. Neutralisation as an Ionic Reaction — H⁺ + OH⁻ → H₂O and spectator ions
  15. Writing Balanced Neutralisation Equations — Symbol equations with state symbols for acid–alkali reactions
  16. Acids Reacting with Metals — Salt plus hydrogen; reactivity and the pop test
  17. Acids Reacting with Metal Oxides — Insoluble bases forming a salt and water
  18. Acids Reacting with Metal Hydroxides — Soluble and insoluble hydroxides as bases
  19. Acids Reacting with Carbonates — Salt, water and carbon dioxide; the limewater test
  20. Acids Reacting with Hydrogencarbonates — Baking soda, effervescence and everyday fizz
  21. Ammonia as a Base — Forming ammonium salts without water
  22. Energy Changes in Neutralisation — Exothermic neutralisation and temperature rise
  23. Following Neutralisation with pH Curves — How pH changes as alkali is added; the end point
  24. Titration: The Idea — Finding exact reacting volumes with an indicator
  25. Choosing an Indicator for Titration — Sharp colour change at the end point
  26. Titration Calculations: Concentration — Using moles and volumes to find an unknown concentration
  27. What Is a Salt? — Ionic compounds from replacing the hydrogen of an acid
  28. Naming Salts — Chlorides, sulfates, nitrates, carbonates and ethanoates
  29. Writing Formulae of Salts — Balancing ionic charges to build salt formulae
  30. Solubility Rules for Salts — Which common salts dissolve in water and which do not
  31. Preparing a Soluble Salt from an Insoluble Base — Excess base, filtration and crystallisation in outline
  32. Preparing a Soluble Salt by Titration — Acid plus alkali when both reactants are soluble
  33. Preparing an Insoluble Salt by Precipitation — Mixing two solutions, filtering, washing and drying
  34. Ionic Equations for Precipitation — Showing only the ions that form the solid
  35. Crystallisation and Water of Crystallisation — Hydrated salts such as blue copper(II) sulfate
  36. Acidic, Basic and Neutral Salts — Why some salt solutions are not pH 7
  37. Acidic and Basic Oxides — Non-metal oxides as acidic, metal oxides as basic
  38. Amphoteric Oxides — Oxides that react with both acids and bases
  39. Testing for Ions in Salts — Carbonate, sulfate and halide tests in outline
  40. pH in the Human Body — Stomach acid, blood pH and digestive enzymes
  41. Soil pH and Agriculture — Liming acidic soils and crop tolerance
  42. Acid Rain and Its Effects — Sulfur and nitrogen oxides, lakes, forests and buildings
  43. Fertilisers as Salts — Ammonium nitrate, ammonium sulfate and NPK
  44. Salts in Food and Medicine — Sodium chloride, baking powder, antacids and barium meals
  45. Acids and Bases in Industry — Sulfuric acid, cleaning products and water treatment
  46. Buffers in Everyday Life — Resisting pH change in blood and products
  47. Safety with Acids, Bases and Salts — Hazard symbols, corrosive substances and safe dilution principles
  48. Common Errors in Acid–Base Chemistry — Strength versus concentration, salt products and equation slips
  49. Problem Solving with Acids, Bases and Salts — Multi-step questions linking pH, reactions and salt preparation
  50. Acids, Bases and Salts: Unit Review — Key ideas, equations and connections across the unit