Pressure Flashcards
Describe the structure of particles in a gas.
Particles in a gas have almost no forces
between them therefore they are completely
free to move, and move at high speeds in
random directions
Explain the pressure of a gas in terms of the motion
of particles
The particles move in random directions. When
they collide with the walls of a container they
exert a force which acts at a right angle to the
container. This causes pressure.
State the equation used to calculate pressure. Give
appropriate units.
Pressure (Pa) = Force (N) / Area (m²)
P = F / A
What factor affects the average kinetic energy of gas
molecules?
● The temperature of the gas
● 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?
Gas pressure 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
each surface of the container
● 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 so rate of
collision decreases
● 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?
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
How do you convert between degree celsius and
kelvin?
Degrees Celsius,℃ + 273= Kelvin, K
Kelvin, K - 273= Degrees Celsius,℃
What is absolute zero?
−273 °C
Particles have no kinetic energy and do
not move.
What equation can be used to calculate the
pressure/volume for a gas for which the mass is
fixed and temperature is constant?
P₁ × V₁ = P₂ × V₂
