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Particle Motion in Gases - Coggle Diagram
Particle Motion in Gases
Particle Motion in Gases
The particles in a gas are moving very quickly in random directions. The speeds of the particles vary but, on average, they move quicker than they do in liquids and solids.
This means that it does not take long for a gas to spread out to fill its entire container. The smell of an air freshener can spread all around a room very quickly.
Gas pressure
since the particles in a gas are moving fast and randomly, collisions occur frequently. These collisions may be between two particles, between a particle and the wall of the container, or between a particle and something else in the container.
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For example, the collisions caused by a gas trapped inside a balloon cause forces to act outwards in all directions, giving the balloon its shape.
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The pressure in the atmosphere (atmospheric pressure) at sea level is about 100,000 N/m2.
The pressure from gas molecules may increase if there are more molecules colliding each second or if the molecules are moving faster.
Pressure and temperature
The temperature of a gas is a measure of the average kinetic energy of its particles – the higher the temperature, the higher the average kinetic energy.
If the volume of a container with a gas inside stays the same, the pressure of a gas increases as its temperature increases.
When hotter, the gas particles will be travelling faster and will collide with the walls of the container more frequently and with more force.
means that there is a relationship between pressure and temperature. If a pressure gauge is connected to a flask of air and the flask is heated, a graph of pressure against temperature can be produced.
Kelvin temperatures
As the temperature of a gas increases, the pressure increases, showing a linear relationship between the two. If the temperature axis is rescaled, the graph shows that pressure is directly proportional to temperature.
The rescaling needed is to put the zero on the temperature scale at -273 °C. This is an alternative temperature scale called the Kelvin (or 'absolute') scale of temperature. This new zero of temperature is called absolute zero. At absolute zero, the average kinetic energy of the particles is zero and they stop moving.
Each degree Celsius is the same size as one kelvin. Raising the temperature by one degree Celsius also increases the value on the kelvin temperature scale by one.