5 c) ideal gas molecules Flashcards
5.7 understand the significance of Brownian motion, as supporting evidence for particle theory
One piece of evidence for the continual motion of particles in a liquid or a gas is called Brownian motion. Particles of a liquid or gas are moving around continually and bump into each other and into tiny particles such as pollen grains. Sometimes there will be more collisions on one side of a pollen grain than on another, and this will make the pollen grain change its direction or speed of movement.
5.8 understand that molecules in a gas have a random motion and that they exert a force and hence a pressure on the walls of the container
Gases are made up of particles that are moving. The particles in gases are spread out and constantly moving in random. They hit the walls of the container and create pressure.
5.9 understand why there is an absolute zero of temperature which is –273oC
Temperature affect the pressure of particles of gases. The higher the temperature, the higher the energy in particles and more the pressure. If we decrease the temperature the result will be the exact opposite. As we cool the gas, the pressure keeps decreasing. The pressure of the gas cannot become less than zero. The temperature at which the pressure of the gas is decreased to 0, that temperature is called absolute zero. It is approximately –273oC.
5.10 describe the Kelvin scale of temperature and be able to convert between the Kelvin and Celsius scales
Temperature in K = temperature in oC + 273
Temperature in oC = temperature in K - 273
5.11 understand that an increase in temperature results in an increase in the average speed of gas molecules
If we heat gas molecules, they gain more kinetic energy. As they do so, they begin to move faster and the average speed of the molecules increases.
5.12 describe the qualitative relationship between pressure and Kelvin temperature for a gas in a sealed container
The number of gas particles and the space, or volume, they occupy remain constant. When we heat the gas the particles continue to move randomly, bu with a higher average speed. This means that their collisions with the walls of the container are harder and happen more often. This results in the average pressure exerted by the particles increasing.
When we cool a gas the kinetic energy of its particles decreases. The lower the temperature of a gas the lass kinetic energy its particles have – they move more slowly. At absolute zero the particles have no thermal or movement energy, so they cannot exert pressure.
5.13 use the relationship between the pressure and volume of a fixed mass of gas at constant temperature:
p1V1 = p2V2
p1 x v1 = p2 x v2
