MAKING SALTS

METAL + ACID ----> SALT + HYDROGEN

Obtaining copper salt crystals

When metals react with acids they lose electrons to become positive ions

ACID + BASE ----> SALT + WATER

Alkalies are bases which are soluble in water

Most bases are metal oxides

Alkali metals never added to acid - too violent of a reaction

NEUTRALISATION REACTION

Obtaining sulfate crystals from copper oxide and sulfuric acid

  1. Add insoluble copper oxide to sulfuric acid and stir
  2. Warm gently over bunsen burner
  3. The solution will turn blue when the reaction is taking place (this is the copper sulfate). Excess black copper oxide can be seen
  4. Once reaction is complete, filter excess copper oxide
  5. Evaporate water until the first crystals start to appear around edge. Leave rest of water to evaporate slowly (larger crystals)
  6. Dry crystals to remove any excess solution

Salts are made up from + and - ions:

  • positive ions = metals, base, carbonate
    • negative ions = acid
  1. Measure acid, warm gently over bunsen burner - DON'T BOIL
  2. Add metal oxide to beaker whilst acid is warm and continue adding until no more dissolves
  3. Cool then filter out undissolved metal oxide
  4. Evaporate until volume halves (POINT OF CRYSTALLISATION), leave to crystallise at room temp
  5. Dry crystals with paper towel

ACID + ALKALI ---> SALT + WATER

NEUTRALISATION REACTION

Use an acid-base indicator to tell when reaction is complete, as no gas is given off and there is no excess insoluble solid

Obtaining crystals

  1. Use titration to find out how much acid is needed to neutralise the alkali
  2. Add this volume of acid to the alkali (NO INDICATOR)
  3. Heat and evaporate to form crystals

ACID + CARBONATE -----> SALT + WATER + CARBON DIOXIDE

Obtaining the crystals

  1. Add enough carbonate to the acid until no more dissolves
  2. Filter the unreacted metal carbonate
  3. Evaporate until solution is halved
  4. Leave to cool and crystallise