RP - SALTS

• Soluble salt

  • Contains a positive metal ion
  • Contains a negative ion from the acid
• Sources of metal ion for a salt

  • Metal
  • Metal oxide
  • Metal hydroxide
  • Metal carbonate
• Making a soluble salt using a metal oxide and acid

  1. Measure out dilute sulfuric acid (limiting reactant)

  2. Gently heat the acid

  3. Add small amounts of copper oxide and stir

  4. Continue adding copper oxide until solution is blue

  5. Filter out any unreacted copper oxide

  6. Evaporate solution to form crystals

  7. Leave to cool and form pure dry crystals
• Cannot make copper sulfate by reacting copper metal with dilute sulfuric acid as copper is not reactive enough
• Copper sulfate solution will turn blue in colour
• Reaction stops when all acid has reacted, leaving a neutral solution
• Filtering removes any unreacted insoluble copper oxide
• Evaporation is used to form pure dry crystals of the salt
• Preparing a dry solid sample of copper sulfate

  1. Measure sulfuric acid

  2. Heat the acid

  3. Add copper oxide

  4. Stir to react

  5. Filter to remove excess copper oxide

  6. Evaporate to get dry crystals
• Neutralization


  Reaction of an acid with a base to form a salt
• Base


  Any material that will neutralize an acid and form a salt (not just alkalis)
• Bases


  • Metal oxides
  • Metal carbonates
  • Metal hydroxides
• Adding excess base


  Ensures all acid is neutralized
• Filtering


  Removes unreacted base from the salt solution
• Evaporation


  Removes water to obtain dry salt crystals
• Heating copper sulfate crystals too much causes them to break down and release nasty gases
• Gentle heating over a steam bath is used to avoid overheating the copper sulfate
• The final product is a sample of pure dry copper sulfate crystals