# P7.4

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• Created by: amy_mair
• Created on: 23-06-16 21:23
• P7.4
• Gas Behaviour
• Kinetic Theory
• It shows that gases are randomly moving particles
• 1. Kinetic Theory says that gases consist of very small particles
• Oxygen consists of oxygen molecules
• 2. These particles are constantly moving in completly random directions
• 3. They constantly collide with each other and with the walls of their container. When they collide, they bounce off each other
• 4. The particles hardly take up any space. Most of the gas is empty space
• Kelvin
• 273
• 1. If you increase the temperature of something you give the particles more kinetic energy- they move about more quickly or vibrate more. In the same way if you cool a substance down, you are reducing the kinetic energy of the particles
• 2. The coldest anything can get is -273- this temperature is known as absolute zero.
• 3. Absolute 0 is the start of the Kelvin scale of temperature
• 4. A temperature change of 1 degrees is also a change of 1 kelvin
• 5. Convert from degrees celcius to kelvins just add 273. And to convert from kelvins to degrees celcius just subtract 273
• Kinetic Energy
• It is proportional to temperature
• 1. Anything that is moving has kinetic energy
• 2. If you increase the temperature of a gas you give its particles more energy
• 3. In fact if you double the absolute temperature you double the average kinetic energy of the particles
• The temperature of a gas is proportional to the average kinetic energy of its particles
• Gas Laws
• Volume and Pressure
• A decrease in volume gives an increase in pressure
• 1. As gas particles move about, they bang into each other and whatever gets in the way
• 2. Gas particles have some mass, so when they collide with something, they exert a force on it. In a sealed container it creates an outward pressure
• 3. If you put the same amount of gas in a bigger container then the pressure will decrease
• 4. So the volume of a gas is inversely proportional to its pressure at a constant temperature
• Pressure x volume = constant
• Temperature and Pressure
• The pressure of a gas depends on how fast the articles are moving
• 2. If you heat a gas, the particles move faster and have more kinetic energy.
• This increase in kinetic energy means the particles hit the container wall harder and more often which creates more pressure
• 3. Pressure is proportional to absolute temperature- doubling the temperature doubles the pressure
• Pressure / temperature = constant
• Temperature and Volume
• 1. If a gas stays at a constant pressure, then heating it up increases the volume- the molecules are further apart so collisions happen less frequently this means there is more force
• 2. Volume is proportional to absolute temperature. Doubling the temperature, doubles the volume
• Volume / temperature = constant
• Fusion
• Discovery
• 1. Scientists used to believe that the sun just burned its own materials. They realised in the centuary that the sun would have run out by now
• 2. Einstein realised that mass could be converted to energy
• 3. It was suggested that hydrogen is turned into helium inside the sun.
• This means that mass is lost as mass is changed into energy
• 4. They found that fusion must be the power source of the sun
• Fuse
• 1. Two nuclei can combine to create a larger nucleus
• In stars hydrogen nuclei fuse together to make helium nuclei
• 3. Energy is liberated when lighter nuclei fuse to make heavier nuclei up to the size of iron
• 4. Nuclei can only fuse like this if they are brought together
• 5. For that you need high temperatures and pressures
• Converts mass into energy
• energy = mass x the speed of light squared
• Mass can be converted into other forms of energy
• When nuclei undergo nuclear fusion they lose mass and energy is released