PH

• What does the pH scale measure?

  The acidity or alkalinity of an aqueous solution
• How can the pH of a solution be measured?

  Using a pH probe or universal indicator
• What does a universal indicator do?

  It changes the colour of the solution based on acidity or alkalinity
• What are the general reactions of acids with metal oxides and metal carbonates?

  • Acid + metal oxide → salt + water
  • Acid + metal carbonate → salt + water + carbon dioxide
• How can acids be neutralised?

  By bases, also known as alkalis
• What is produced when an acid reacts with an alkali?

  Water, H₂O, which has a pH of 7 (neutral)
• What ions do acids and alkalis contain?

  Acids contain hydrogen ions, H⁺, and alkalis contain hydroxide ions, OH⁻
• What happens to hydrogen ions in an acid during a reaction?


  They are replaced by a metal ion to form a salt
• What types of salts are produced from different acids?

  • Hydrochloric acid produces chloride salts
  • Nitric acid produces nitrate salts
  • Sulfuric acid produces sulfate salts
• What is the method for making soluble salts from insoluble bases?

  1. React acids with insoluble bases (metal oxides, hydroxides, carbonates)
  2. Add acid to a beaker
  3. Add insoluble base until in excess
  4. Filter out excess base
  5. Evaporate the solution to crystallise the salt
• What is the first step in the experiment to make soluble salts using magnesium carbonate and hydrochloric acid?

  Pour hydrochloric acid into a beaker
• What should you do after adding magnesium carbonate to hydrochloric acid until in excess?

  Filter the excess out with filter paper and funnel
• What is the purpose of gently warming the solution in the evaporating basin?

  To help the water evaporate and crystallise the salt
• What safety equipment should be used during the experiment?

  Safety goggles