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Jumpin’ Jack Flash It’s a gas gas gas! PowerPoint Presentation
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Jumpin’ Jack Flash It’s a gas gas gas!

Jumpin’ Jack Flash It’s a gas gas gas!

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Jumpin’ Jack Flash It’s a gas gas gas!

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  1. Jumpin’ Jack FlashIt’s a gas gas gas! Solids, Liquids and Gases and Gas Laws Chapter 7

  2. Solids, liquids and Gases At the end of this section you should be able to: • use the kinetic theory of matter to explain properties of gases, liquids and solids • describe the qualitative effect on gases of changes in pressure, volume and temperature • describe the changes in temperature, potential energy and kinetic energy when a substance undergoes phase changes • explain the factors that affect the vapour pressure of a liquid • explain the relationship between vapour pressure and boiling temperature • use the Kinetic Theory of Matter to explain • relationship between heat and temperature • change of phase • vapour pressure and factors that affect vapour pressure • effect on gases of changes in pressure, temperature and volume • the characteristics of gases • predict the effect on gases of changes in pressure, temperature and volume (qualitative only) • explain the boiling point of a liquid. • Gases, liquids and solids • Behaviour of gases − kinetic theory • Gas pressure, volume and temperature • Volume and amount of gas • Liquids and solids • Changes in state • Evaporation, vapour pressure and boiling • Pure substances and mixtures From the 2AB Chemistry Course Outline

  3. Try thinking of a gas Air is a good one Can you list some of the gases that make up air? N2 O2 CO2 H2 Ne He Ar From which kind of element are these all made up? Think about the particles of a gas What do they look like? Are they big? Small? Characteristics of Gases

  4. How would you describe a gas what it does? what it looks like? shape? behaviour? how did it get to be a gas? What would be the best description you could give a gas? What are some ideas we use to describe what gases do? Pressure Volume Temperature How much (number of moles) Any more? Characteristics of Gases

  5. What do each of these words mean? KINETIC THEORY of GASES Ideal gas - what is this? All gases behave in generally the same manner*, so we can generalise their behaviour and devise a set of rules to predict and describe this behaviour THE GAS LAWS Kinetic Theory of Gases

  6. So which gas is an ideal gas? Well… none of them are Why? Recall “All gases behave in generally the same manner*...” this is generally true for a limited set of circumstances - for a limited set of values for… PRESSURE VOLUME TEMPERATURE NUMBER OF MOLES Kinetic Theory of Gases

  7. Kinetic Theory of Gases • Model of Gas motion

  8. What causes the pressure of a gas in a closed container? Impacts of gas molecules with the walls of the container. Anything that increases the number of impacts per second or the force of each impact increases the pressure. Microscopic View

  9. Light molecules move faster and hit the walls more often. Heavy molecules hit the walls with lower velocity and less frequency, but the same force. These 2 effects exactly balance out. **Gas pressure doesn’t depend on the identity of the gas.**

  10. The kinetic theory of gases is the best approximation of the way gases behave. Its description of gases is based on the following assumptions Kinetic Theory of Gases 1. Gases consist of tiny particles called molecules, except for the noble gases which consist of atoms 2. The average distance between the molecules of a gas is large compared with the size of each gas molecule 3. The molecules of a gas move in rapid, random, straight line motion. These movements result in collisions with each other and with the sides of the container 1. GASES R TINY 4. The molecules of a gas exert negligible attractive or repulsive forces on one another 5. All collisions of gas molecules are perfectly elastic. This means there is no net energy loss during these collisions 6. The kinetic energy of the molecules increases with temperature 2. Little gas, lotsa space 3. Random, rapid, straight  collisions 4. No attraction / repulsion 5. Collisions elastic 6. T KE

  11. Pressure Depends on 1) the concentration or # of gas molecules per unit volume and 2) the temperature.

  12. How fast do the molecules in the air move? • Depends on the mass. • Light molecules are faster than heavy molecules at the same temperature. • Temperature = measure of the ave. translational K.E. of the particles of a system.

  13. Molecular Speeds at 298 K • H2 1.93 X 105 cm/sec • He 1.36 X 105 cm/sec • O2 4.82 X 104 cm/sec • Ar 4.31 X 104 cm/sec • Xe 2.38 X 104 cm/sec

  14. HOW IS KINETIC ENERGY DISTRIBUTED IN A LIQUID?

  15. LOW HIGH kinetic kinetic energy energy

  16. LOW HIGH kinetic kinetic energy energy

  17. LOW HIGH kinetic kinetic energy energy

  18. LOW HIGH kinetic kinetic energy energy

  19. LOW HIGH kinetic kinetic energy energy

  20. LOW HIGH kinetic kinetic energy energy

  21. LOW HIGH kinetic kinetic energy energy

  22. LOW HIGH kinetic kinetic energy energy COLD HOT

  23. kinetickinetic kinetic energyenergy energy COLD HOT LOWINTERMEDIATEHIGH

  24. kinetickinetic kinetic energyenergy energy COLD HOT How many water molecules have intermediate K.E.? How many water molecules have HIGH K.E.? How many water molecules have LOW K.E.? LOWINTERMEDIATEHIGH

  25. L O W I N T E R M E D I A T E H I G H k i n e t i c k i n e t i c k i n e t i c e n e r g y e n e r g y e n e r g y

  26. Number of particles

  27. Number of particles low high kinetic energy

  28. low K.E. high K.E. Number of particles average K.E. = temperature of liquid

  29. WHAT HAPPENS TO A LIQUID’S TEMPERATURE DURING EVAPORATION?

  30. low temperature high temperature temperature of liquid

  31. low high temperature 1

  32. low high temperature 2

  33. low high temperature 2

  34. Molecular Speed vs. Temperature

  35. Pressure – Microscopic View • Gas molecules hit the walls of their container. • Pressure depends on • Number of impacts per unit time • Force of each impact

  36. Pressure – Macroscopic View • Pressure depends onhow many gas molecules per unit volume and on thetemperature. • The same amount of gas exerts different pressure at different temperatures (tires).

  37. Avogadro’s Law • Equal volumes of gases at the same pressure and temperature contain the same number of “particles.” • V = an where V = volume of the gas, n= # of moles of gas, & a is a constant. http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter09/Text_Images/FG09_09.JPG