Solubility

• Ionic compounds


  • Made up of charged particles called ions
  • Ions form when atoms loose of gain an electron
  • Ionic compounds consist of both positive and negative ions
  • Most ionic compounds occur naturally. Can be found solid crystals/rocks or more commonly found dissolved in water. This is because many ionic compounds are soluble in water
• What is salt made out of?

  Sodium chloride
• How do ions behave in a solution

  They move about freely and they are seperate
• Why are precipitate reactions important?



  • They can be used in qualitative tests to identify ions
  • They can also be used to make useful products
  • Examples of this is Lead iodide and Barium sulfate
• General rules for solubility

  1. All salts that contain sodium, Potassium and Ammonium are soluble
  2. All sates that contain nitrates are soluble
  3. Salts that contain chloride are soluble
  4. Salts containing sulphates are soluble
  5. Common carbonates and hydroxides are insoluble
• General rules for solubility exceptions

  1. Silver and lead chlorides are insoluble
  2. Lead barium and calcium sulphates are insoluble
  3. Carbonates and hydroxides of sodium, potassium and ammonium are soluble
• Precipitation reaction


  • A reaction in which soluble ions in separate solutions mix together to form an insoluble compound
  • The insoluble compound is called a precipitate
• What is an important insoluble salt?

  • Barium sulphate
  • Used in medical imaging to diagnose intestinal problems