C3-chemical changes

• Which ion makes a solution acidic?

  Hydrogen ions / H+

  Which ion makes a solution alkaline?

  Hydroxide ions / OH-
• Hydrogen ions

  Make a solution acidic
• Hydroxide ions

  Make a solution alkaline
• pH of a neutral solution

  7
• pH of an acidic solution

  Less than 7
• pH of an alkaline solution

  More than 7
• Litmus in acid and alkali


  Red in acid, blue in alkali
• Methyl orange in acid and alkali

  Red in acid, yellow in alkali
• Phenolphthalein in acid and alkali

  Colourless in acid, pink in alkali
• As hydrogen ion concentration increases

  pH decreases
• As hydroxide ion concentration increases

  pH increases
• If hydrogen ion concentration increases by a factor of 10

  pH decreases by 1
• As calcium hydroxide or oxide is added to dilute hydrochloric acid


  pH increases
• Balance

  Can be used to measure the mass of a reactant
• Measuring cylinder

  Can be used to measure the volume of a solution
• pH meter

  Can be used instead of an indicator to measure the pH of a solution
• Strong acid

  An acid that fully dissociates into ions
• Weak acid

  An acid that does not fully dissociates into ions
• Base

  Any substance that reacts with an acid to form a salt and water only
• Alkali

  A soluble base
• Acid reacting with a base

  Acid + base → salt + water
• Test for hydrogen

  A lit splint gives a squeaky pop if hydrogen is present
• Test for carbon dioxide

  Bubble the gas through limewater. The limewater turns cloudy if carbon dioxide is present.
• Test for oxygen

  A glowing splint relights in the presence of oxygen
• Ionic equation for neutralisation

  H+ (aq) + OH- (aq) → H2O (l)
• Preparing a soluble salt from an acid and an insoluble reactant

  Add an excess of the reactant, filter the excess reactant, leave the solution to evaporate
• Preparing a soluble salt from an acid and a soluble reactant

  Titration, repeat with correct volumes without an indicator, leave the solution to evaporate
• Soluble


  Something that will dissolve
• Insoluble

  Something that won't dissolve
• Copper oxide

  Black solid (powder)
• Copper sulfate solution

  Blue
• Burette


  This piece of equipment
• Pipette

  This piece of equipment
• Ions that make a compound always soluble

  • Sodium
  • Potassium
  • Ammonium
  • Nitrate
• Chlorides that are insoluble

  • Silver chloride
  • Lead chloride
• Sulfates that are insoluble

  • Lead sulfate
  • Barium sulfate
  • Calcium sulfate
• Carbonates that are soluble

  • Sodium carbonate
  • Potassium carbonate
  • Ammonium carbonate
• Hydroxides that are soluble

  • Sodium hydroxide
  • Potassium hydroxide
  • Ammonium hydroxide
• Precipitate

  A solid that is formed in a solution
• State symbols

  • (s) = solid
  • (l) = liquid
  • (g) = gas
  • (aq) = aqueous (dissolved in water)