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# Kinetic Theory and Gas Pressure

Kinetic Theory and Gas Pressure. Objectives (d) define the term pressure and use the kinetic model to explain the pressure exerted by gases; (i) state the basic assumptions of the kinetic theory of gases;. Outcomes. ALL MUST Be able to define pressure.

## Kinetic Theory and Gas Pressure

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### Presentation Transcript

1. Kinetic Theory and Gas Pressure Objectives (d) define the term pressure and use the kinetic model to explain the pressure exerted by gases; (i) state the basic assumptions of the kinetic theory of gases;

2. Outcomes ALL MUST Be able to define pressure. Be able to use the kinetic model to describe pressure. MOST SHOULD Be able to state the basic assumptions of the kinetic theory of gases. Be able to use the kinetic model to explain the pressure exerted by gases. Be able to select and use the equation p=1/3ρv2 SOME COULD Be able to derive the equation p=1/3ρv2

3. Pressure P (Pa) = F (N) / A (m2)

4. The Kinetic Theory of Gases Question (We do not have enough particles here to be realistic but it will illustrate the point!) 6 particles have the following speeds: 600, 650, 650, 700, 725, 750ms-1. Determine the most probable speed cp, the mean speed and the root mean square speed crms. Thermodynamics

5. The Kinetic Theory of Gases 6 particles have the following speeds: 600, 650, 650, 700, 725, 750ms-1. The most probable speed cp = 650ms-1 as there are more particles going at that speed than any other. Thermodynamics

6. The Kinetic Theory of Gases 6 particles have the following speeds: 600, 650, 650, 700, 725, 750ms-1. Thermodynamics

7. The Kinetic Theory of Gases 6 particles have the following speeds: 600, 650, 650, 700, 725, 750ms-1. Thermodynamics

8. Assumptions of the kinetic theory of an IDEAL GAS. 1 1 A Gas consists of particles called molecules. 2 2 The molecules are in constant random motion. As many travelling in one direction as any other. The centre of mass of the gas is at rest. 3 Intermolecular forces are negligible. 4 The duration of collisions between molecules is negligible. 5 Molecules move with constant velocity in between collisions. 6 6 The volume of gas molecules is negligible compared with the volume of the gas. 7 All collisions are totally elastic. 8 Newtonian mechanics can be applied to the collisions.

9. The Kinetic Theory of Gases If these assumptions are correct, we should be able to prove the equation of state for an ideal gas from these assumptions! WOW! Thermodynamics

10. The Kinetic Theory of Gases Consider the change in momentum as the particle hits the wall Thermodynamics

11. The Kinetic Theory of Gases So Thermodynamics

12. Outcomes ALL MUST Be able to define pressure. Be able to use the kinetic model to describe pressure. MOST SHOULD Be able to state the basic assumptions of the kinetic theory of gases. Be able to use the kinetic model to explain the pressure exerted by gases. Be able to select and use the equation p=1/3ρv2 SOME COULD Be able to derive the equation p=1/3ρv2

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