Topic 3 - Particle Model of Matter - 3.3 - Particle Model and Pressure Flashcards
Describe the motionof molecules in a
gas.
They are in constant random motion.
What factor affects the average kinetic
energy of gas 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 B than in gas A
●The rate of collisions is higher in B
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 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
