Gases Flashcards
(18 cards)
What is the kinetic theory of gases?
Based on the notion of an ideal gas
What does the kinetic theory of gas propose? (6)
Gases consist of molecules (except for the Nobel gases, which consist of atoms that move in continual, random, rapid and straight-line motion
The average distance between gas molecules is ver large compared to the size of the molecule itself
No forces of attraction between gas molecules
All collisions between gas molecules are perfectly elastic
Gas pressure is caused by collisions of the gas molecules with the walls of the container that the gas is stored in
Temperature of a gas is a measure of the average kinetic energy of the gas molecules
What does the kinetic theory propose? (Distance)
The average distance between gas molecules is very large compared to the size of the molecule itself
What does the kinetic theory propose? (Forces of attraction)
There are no forces of attraction between gas molecules
What does the kinetic theory propose? (Collisions)
All collisions between gas molecules are perfectly elastic.
There is no energy lost when gas molecules collide
What does the kinetic theory propose? (Pressure)
Gas pressure is caused by collisions of the gas molecules with the walls of the container that the gas is stored in
What does the kinetic theory explain?
It explains the behaviour of gases
Hydrogen and helium are very light gases and come close to behaving as “ideal gases” under high temperature and low pressure conditions. The fact that gases can be cooled and condensed into liquids and then with further cooling solidified shows us that there are forces of attraction between gas molecules.
What does the kinetic theory of gases propose? (Molecules)
Gases consist of molecules (except for the Nobel gases, which consist of atoms) that move in continual, random, straight-line motion, rapid
What does the kinetic theory propose about temperature ?
The kinetic theory states that temperature is a measure of the average kinetic energy of the particles in a substance
At any given temperature the particles in a substance have a range of kinetic energies
What are the 5 physical properties common to all gases?
Gases take the shape of their container
Gases have a low density
Gases diffuse
Gases can be easily compressed
Gases exert pressure
Why do gases diffuse? (3)
Particles of gas are in constant random motion, have negligible forces of attraction and are widely spaced.
So they spread out and equalise between the molecules of any other gas
Why can gases be easily compressed? (2)
particles of gas have negligible volume
widely spaced so there is room for them to be compressed into a smaller volume
Why do gases spread to fill a container? (2)
there are negligible forces of attraction between particles and are in constant motion.
Instead of clumping together, they spread out as far as possible occupying the entire volume and shape of the container
Why do gases exert pressure? (3)
Particles in the gas phase do not attract one another but move randomly in straight lines.
They collide with their container walls they exert pressure on the walls.
The pressure increases with the frequency and force of these collisions.
Why do gases have low density? (1)
density = mass / volume
particles have a lot of empty space between them
What are 2 difference between an ideal gas and real gases?
Particles of an ideal gas have negligible volume
While particles of a real gas do occupy space and their volume is sometimes significant when compared to the volume occupied by the gas as a whole
Ideal gases have negligible attraction for one another. While the particles of real gases do have forces of attraction for one another and these forces of attraction can become significant.
What is a real gas?
gases like H2, N2 or HCl
What are the 2 other differences between an ideal gas and real gases
At 0K an ideal gas would have zero volume.
A real gas will never have zero volume as its particles occupy space
if a real gas is cooled and/or compressed sufficiently it will condense to form a liquid, due to their weak inter-particle attraction.
Ideal gas would never condense as its particles always have negligible attraction for one another.
