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Do Now – 4 marks

Do Now – 4 marks. Mark scheme. Boiling and evaporation. Learning today What is evaporation How to increase the rate of evaporation. C ondensation Boiling. Solids, liquids and gases. Internal Energy.

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Do Now – 4 marks

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  1. Do Now – 4 marks

  2. Mark scheme

  3. Boiling and evaporation Learning today • What is evaporation • How to increase the rate of evaporation. • Condensation • Boiling

  4. Solids, liquids and gases

  5. Internal Energy This is the sum of the kinetic energies - from motion of the particles and potential energies due to forces between the molecules in a substance If you imagine the forces between particles as a spring, you can see if the particles are pulled apart or squashed together that energy is stored in the spring. Similarly there is potential energy between the particles in a substance.

  6. Temperature Temperature is a measure of the average random kinetic energy of the particles in a substance. Note that they are not all travelling at the same speed.

  7. Melting? • Changes in kinetic energy and potential energy?

  8. Evaporation? • Changes in kinetic energy and potential energy?

  9. Condensing? • Changes in kinetic energy and potential energy?

  10. Freezing? • Changes in kinetic energy and potential energy? • What is happening

  11. Boiling and evaporation

  12. Evaporation Consider a beaker of water at room temperature

  13. Evaporation The molecules of water are moving around at different speeds, some fast, some slow. # of molecules at a particular speed speed of molecule (m/s) Average speed

  14. Evaporation If a molecule is at the surface, and moving fast enough, it may escape the liquid. This is called evaporation. Freedom!

  15. Evaporation Since the average speed of the remaining molecules must now be lower, the temperature of the liquid drops (since temperature is a measure of the kinetic energy of the molecules). Freedom!

  16. Evaporation – Please copy If a molecule is at the surface, and moving fast enough, it has enough energy to break bonds and escape the liquid. This is called evaporation. It can happen at any temperature and as it is the molecules with the greater KE escaping the temperature of the liquid reduces. Freedom!

  17. Evaporation If a molecule is at the surface, and moving fast enough, it has enough energy to break bonds and escape the liquid. This is called evaporation. It can happen at any temperature and as it is the molecules with the greater KE escaping the temperature of the liquid reduces. Freedom!

  18. Evaporation If a molecule is at the surface, and moving fast enough, it has enough energy to break bonds and escape the liquid. This is called evaporation. It can happen at any temperature and as it is the molecules with the greater KE escaping the temperature of the liquid reduces. Freedom!

  19. Evaporation Evaporation can thus take place at any temperature.

  20. Increasing the rate of evaporation Increasing the temperature.

  21. Increasing the rate of evaporation Increasing the temperature means that more molecules are moving fast enough to escape.

  22. Increasing the rate of evaporation Increasing the surface area

  23. Increasing the rate of evaporation Increasing the surface area means that more molecules are at the surface.

  24. Increasing the rate of evaporation Increasing the air flow over the surface

  25. Increasing the rate of evaporation Increasing the air flow over the surface so that molecules are carried away before they can fall back into the liquid

  26. Increasing the rate of evaporation Decreasing the humidity of the surrounding atmosphere

  27. Increasing the rate of evaporation Decreasing the humidity of the surrounding atmosphere to stop water molecules from the atmosphere entering the liquid.

  28. please copy Evaporation can be increasedby • Increasingtemperature • more particleshave a higher KE • Increasingthesurfacearea • more particlesclosertothesurface • Increasing air flowabovethesurface • givestheparticlessomewheretogoto • - Evaporation and Condensation.flv

  29. Boiling and evaporation

  30. Boiling Boiling occurs when vapour is produced in the body of the liquid.

  31. Boiling Boiling occurs when vapour is produced in the body of the liquid. The bubble contains only water vapour, not air!

  32. Boiling – Please copy Boiling occurs when vapour is produced in the body of the liquid. This only happens at the boiling point of the liquid. The bubble contains only water vapour, not air!

  33. To summarize: Evaporation takes place only at the surface of the liquid and can take place at any temperature.

  34. To summarize: Boiling means bubbles! Boiling occurs when vapour is produced in the body of the liquid. This only happens at the boiling point of the liquid.

  35. Evaporation -3 marks

  36. Markscheme

  37. Homework – 1. Finish Draw these sentences 2. Stick in all your loose worksheets by Sunday 12th February 3 Java Lava Power Homework

  38. Homework • If I give you homework you will do it • I will give you a blue slip if you do not

  39. Got it?

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