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Heating And Cooling L6

Changes of state, Year 8, science

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Heating And Cooling L6

  1. 1. Changes of state Target: To know about the change of state from liquid to a solid. Thursday 3 December 2009
  2. 2. Experiment <ul><li>Place a test tube containing stearic acid into hot water. The solid will melt. </li></ul><ul><li>Remove the test tube and thermometer and place it in a test tube rack. </li></ul><ul><li>Record the temperature for 15 minutes. </li></ul><ul><li>Plot a graph of your results – show temperature against time. </li></ul>Time (min) Temperature ( o C) 0 1 2 3 4 5 6 7 8 9
  3. 3. A change of state is given a name. Solid Liquid Melting Freezing Changes of state
  4. 4. <ul><li>If a liquid is cooled its temperature falls to its freezing point. </li></ul><ul><li>At the freezing point the temperature stops falling while the liquid solidifies. </li></ul><ul><li>Once all the liquid has frozen the temperature of the container starts to fall again. </li></ul>Changes of state – cooling curves The freezing point of a substance is the temperature at which the liquid spontaneously turns into a solid. The freezing point depends of the pressure of the atmosphere above the liquid.
  5. 5. Solid  Liquid Liquid Liquid  Gas Gas Solid Time Changes of State Temperature