Presentation is loading. Please wait.

Presentation is loading. Please wait.

THERMODYNAMICS. Solid Liquid Gas In a solid the particles are packed side by side and cannot move. They vibrate when they are heated In a liquid the particles.

Similar presentations


Presentation on theme: "THERMODYNAMICS. Solid Liquid Gas In a solid the particles are packed side by side and cannot move. They vibrate when they are heated In a liquid the particles."— Presentation transcript:

1 THERMODYNAMICS

2 Solid Liquid Gas In a solid the particles are packed side by side and cannot move. They vibrate when they are heated In a liquid the particles are still joined but can move around In a gas the particles are not joined and can move around in straight lines and do not react with each other

3 Solid Liquid Gas Solids have a shape and a volume Solids cannot be compressed Liquids do not have a shape but have a volume Liquids cannot be compressed Gases do not have shape or volume, they can spread out and fill the shape they are contained in Gases can be compressed

4 GAS LAWS Compression (increasing pressure) is caused by exerting a force on an area Pressure = Force N/m 2 (Pascals) Area Increasing force on the same area means increasing pressure

5 GAS LAWS Force Applying a force on the are of this piston will apply a pressure on the gas inside

6 GAS LAWS Increasing the pressure results in a decrease in volume The volume decreases at the same rate as the pressure increases Force

7 GAS LAWS Mathematically Pressure x volume is a constant (always the same figure) P X V = K P 1 x V 1 = P 2 x V 2 = K Force This is called Boyle’s Law

8 EXAMPLE If the gas in a cylinder has a volume of 4m3 at a pressure of 4 N/m 2 What will the volume be if the pressure is increased to 8 N/m 2 ? P 1 x V1 = P 2 x V 2 = K 4 x 4 = 8 x V 2 = 16 V2 = 16 ÷ 8 = 2m 3

9 GAS LAWS When the gas particles are at a low temperature they have a low amount of kinetic energy and are not moving about very much and do not occupy much volume

10 GAS LAWS When the gas particles are heated to a higher temperature they have more kinetic energy and move about faster occupying a larger volume

11 GAS LAWS When the temperature increases the volume increases V= K T

12 GAS LAWS If the gas is heated and the volume cannot increase (in a closed container) the pressure increases P = K T

13 GAS LAWS Combining the three laws we get P x V = K T

14 GAS LAWS P 1 x V 1 = T 1 P 2 x V 2 T 2 A gas has a constant pressure, temperature and volume, if one of the quantities changes and another stays constant the third will change to compensate

15 ALWAYS USE THE KELVIN TEMPERATURE SCALE IN YOUR CALCULATIONS oCoCKELVIN

16 GAS LAWS EXAMPLE The temperature of 2m 3 of air is 22 o C. It is compressed to a volume of 1.2m 3 whilst being kept at a constant pressure of 1 bar. Calculate the final temperature of the air. Remember to change temperature to Kelvin 22 o C = 295K

17 GAS LAWS EXAMPLE (PRESSURE STAY CONSTANT) V 1 = T 1 V2T2V2T2 2 = T 2

18 GAS LAWS EXAMPLE 2 = 295K 1.2 T 2 T 2 = 295K x T 2 = 177K ( -96 o C)

19 GAS LAWS EXAMPLE  Dry steam is compressed isothermally from a pressure of 1 bar to a pressure of 10 bar. The initial volume of the steam is 2m 3. Calculate the volume of the steam after compression.

20 GAS LAWS EXAMPLE This time temperature stays the same So P 1 V 1 = P 2 V 2 1 x 2 = 10 x V 2 V2 = 1 x 2 = 0.2m 3 10

21 GAS LAWS EXAMPLE An air compressor operates with a compression ratio of 5:1. If the air is at a pressure of 1 bar and a temperature of 20 o C before compression and the temperature after compression is 300 o C. What will the final pressure be? V1 = 5 V2 = 1

22 GAS LAWS EXAMPLE (PRESSURE STAY CONSTANT) P 1 x V 1 = T 1 P 2 x V 2 T 2 1 x P 2 x =

23 GAS LAWS EXAMPLE (PRESSURE STAY CONSTANT) P 1 x V 1 = T 1 P 2 x V 2 T 2 1 x 5 x x1 P2P2 == 9.8 bar


Download ppt "THERMODYNAMICS. Solid Liquid Gas In a solid the particles are packed side by side and cannot move. They vibrate when they are heated In a liquid the particles."

Similar presentations


Ads by Google