1. Heating and Cooling Curves? L/O :- To understand melting, boiling and evaporation

2. How would you separate these? Iron and Sand

3. How would you separate these? Mud and Water

4. How would you separate these? Sand and Water

5. How would you separate these? Salt and Water

6. How would you separate these? Orange Juice and Water

7. State What are the three states? Solid Liquid Gas

8. Changing State Substances change states at given temperatures This is very useful information to know E.g. a mercury thermometer will not work below -39  C - can you guess why? Below this temperature the mercury will freeze (become solid), so cannot move up or down the thermometer! SolidLiquidGas

9. Melting Point This is the temperature a substance turns from a solid to a liquid Different substances have different melting points E.g. water melts at 0  C; ethanol melts at -114  C

10. Melting Point So there is a fixed temperature where a substance turns from a solid to a liquid Don’t forget, this point is also the temperature where a substance turns from a liquid to solid (its freezing point) I.e - water melts at 0  C and above (solid to liquid); and it freezes at 0  C and below (liquid to solid)!

11. Boiling Point This is the temperature at which a substance evaporates as quickly as it can (liquid to gas) Different substances have different boiling points E.g. water boils at 100  C; ethanol boils at 78  C

12. Boiling Points So there is a fixed temperature where a substance boils from a liquid to a gas Don’t forget, this point is also the temperature where a substance turns from a gas to liquid (its condensing point) I.e - water boils at 100  C and above (liquid to gas); and it condenses at 100  C and below (gas to liquid)!

13. State You can identify the state of a substance if you know its temperature, melting and boiling point: –If the temp. is below the melting point, the substance will be a –If the temp. is between the melting and boiling point, the substance will be a –If the temp. is above the boiling point, the substance will be a Complete the sentences, using the either solid; liquid; or gas

14. State You can identify the state of a substance if you know its temperature, melting and boiling point: –If the temp. is below the melting point, the substance will be a solid –If the temp. is between the melting and boiling point, the substance will be a –If the temp. is above the boiling point, the substance will be a

15. State You can identify the state of a substance if you know its temperature, melting and boiling point: –If the temp. is below the melting point, the substance will be a solid –If the temp. is between the melting and boiling point, the substance will be a liquid –If the temp. is above the boiling point, the substance will be a

16. State You can identify the state of a substance if you know its temperature, melting and boiling point: –If the temp. is below the melting point, the substance will be a solid –If the temp. is between the melting and boiling point, the substance will be a liquid –If the temp. is above the boiling point, the substance will be a gas

17. Changing Temperatures If you add other substances then the temperature your original substance freezes, melts and boils can change E.g. salt is added to water to lower the melting point (and freezing point) This is why salt is spread on roads during winter Normally the water would freeze at 0  C Adding the salt means the temperature must be even colder than 0  C for the ice to freeze - useful for cold nights! E.g. solder is a mixture of tin and lead - this mixture results in the melting point being even lower than pure tin or lead, making it useful to join metals together

18. Task Using Exploring Science 8 read through pages 78 and 79 and answer questions 1 to 7…

19. Answers 1.Tungsten melts at 3410  C 2.Liquid sodium boils at 882  C 3.Liquid oxygen boils at -182  C 4.Boiling points are always higher than melting points, because the boiling point is the temperature where the liquid can get no hotter (although the gas can) - so must be higher than the melting point! 5.Iron freezes at 1535  C; oxygen freezes at -218  C; and sodium freeze at 97  C (these are also the temperatures they melt at)! 6.Wax A will be pure - a constant melting point. Wax B had different melting points, suggesting it contained other substances which altered the melting point, depending upon how much of them were present in the sample 7.Air is a mixture of substances (nitrogen; oxygen; argon etc…) so there is no fixed melting or boiling points.

20. Heating Curves