Thermal Decomposition

• Reactants


  Should be on the left side of a word equation
• Thermal decomposition


  A decomposition reaction that requires heating to occur
• Decomposition reaction


  A substance is broken down into more than 1 product
• Thermal decomposition reaction


  • Requires heating to occur
• Thermal decomposition of metal carbonates

  Metal carbonate --> Metal oxide + Carbon dioxide
• Thermal decomposition of metal carbonates

  • Calcium carbonate --> Calcium oxide + Carbon dioxide
  • Lead carbonate --> Lead oxide + Carbon dioxide
  • Copper carbonate --> Copper oxide + Carbon dioxide
  • Zinc carbonate --> Zinc oxide + Carbon dioxide
• Testing for carbon dioxide

  Bubble carbon dioxide into limewater, it gets cloudy
• In a decomposition reaction, a substance breaks down to make simpler compounds and elements. Copper carbonate decomposes to make copper oxide and carbon dioxide gas. You can use limewater to test for the gas.
• Demonstration: Thermal decomposition reactions
• Metal is a type of variable
• A graph should be used to display the results
• Independent variable


  The variable that is changed or manipulated in an investigation
• The independent variable in this investigation was the metal
• Dependent variable


  The variable that is measured or observed in an investigation
• The dependent variable in this investigation was the time for the limewater to turn cloudy
• Control variables are needed to ensure the results are not affected by other factors
• An example of a control variable in this investigation was the amount of limewater used
• Decomposition of a metal carbonate is a chemical reaction, not a physical change, because the composition of the substances changes
• The metal carbonate that decomposed the easiest was the one that took the least time for the limewater to turn cloudy, indicating the fastest production of carbon dioxide
• Thermal decomposition is the process by which a substance breaks down into simpler substances when heated.