Acids, Bases and Salt Preparations

Acid + metal → salt + hydrogen

• Only a metal above hydrogen in the reactivity series reacts with a dilute acid (see topic 13 section 1)
• General reaction:

metal + acid → salt + hydrogen

• Test for the gas: a lit splint at the mouth of the tube gives the squeaky pop of hydrogen
• Examples (using a +2 metal):
  • Zn(s) + 2 HCl(aq) → ZnCl₂(aq) + H₂(g)
  • Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂(g)
• Acid → salt naming rule:
  • Hydrochloric acid gives a chloride
  • Sulfuric acid gives a sulfate
  • Nitric acid gives a nitrate

Acid + base → salt + water

• Reacting any acid with a base is a neutralisation and always gives the same two products: a salt plus water

acid + base → salt + water

Acid + metal carbonate → salt + carbon dioxide + water

• Acids react with metal carbonates to give three products: a salt, carbon dioxide gas, and water

acid + metal carbonate → salt + carbon dioxide + water

• A distinguishing feature is the effervescence as carbon dioxide is released — passing the gas through limewater turns it milky, confirming CO₂
• Examples:
  • CuCO₃(s) + 2 HCl(aq) → CuCl₂(aq) + CO₂(g) + H₂O(l)
  • ZnCO₃(s) + H₂SO₄(aq) → ZnSO₄(aq) + CO₂(g) + H₂O(l)
  • Na₂CO₃(s) + 2 HNO₃(aq) → 2 NaNO₃(aq) + CO₂(g) + H₂O(l)