4.3.3 Particle Model and Pressure Flashcards
Describe the motion in a gas.
They are in constant random motion.
What factors affects the average kinetic energy of gas molecules?
The temperature of the substance.
The higher the temperature, the higher the average kinetic energy of the molecules.
What effect does increasing temperature have on the pressure of a gas when held at constant volume?
Pressure of the gas will increase as the temperature increases.
Why does pressure increase as temperature increases (at a constant volume)?
Kinetic energy of molecules increases.
Collisions between molecules becomes more frequent.
Greater rate of change of momentum.
Greater force and therefore pressure.
If gas A is at a low pressure, and gas B is at a high pressure, what can be said about the rate of collisions in each gas?
There are more collisions per second in gas A than in gas B.
The rate of collisions is higher in A.
Describe the force that the pressure of a gas exerts on the walls of its container.
The net force acts at right-angles to the container’s surface.
The force increases as pressure increases.
Explain how increasing the volume of a gas results in a decrease of pressure.
Molecules become more spread out and so time between collisions increases.
This reduces the rate of collisions.
Rate of change of momentum decreases, and so force exerted on container decreases, resulting in a lower pressure.
What can be said about the product of pressure and volume for a fixed mass of gas at a constant temperature? (Higher)
It is constant.
p V = constant
What is the unit used for pressure?
Pascal (Pa)
What increases when you do work on a gas?
The internal energy of the gas.
This can also lead to an increase of temperature.
Why does the temperature of air inside a bike pump increase when it is pumped?
Work is done on a gas when it is compressed.
Doing work on a gas increases its internal energy, so also increases the average kinetic energy of the molecules.
Temperature increases with an increase of average kinetic energy.
