The Properties of Gases Notes

These notes deal with Gas Laws in chemistry. I state what you have to know and dont do any mathematical problems since they are all excellently covered in the text book. These notes are a help for those that already understand the topic. Im not going to go into depth explaining the concepts in these, or any other chemistry notes because then they cease to be notes but rather a rubbish textbook. Needless to say, experiments are not covered here.


Assumptions of the Kinetic Theory of Gases:

1. particles are constantly moving and colliding with themselves and container walls
2. no attractive/repulsive forces
3. actual volume of gas particles is neglible compared to the volume of their container. thus when measuring the volume of the gas you actually give the volume of the container it is in.
4. Average Kinetic Energy is proportional to temp of gas in Kelvin
5. Collisons between particles involve no loss of kinetic energy

Real gases become more like ideal gases at low pressure and high temperature. Widely spaced molecules so neglible volume compared to container and high energy particles that are not affected by the attractive forces between them. Under the above conditions non polar molecules become closer to the ideal better than polar ones.


A gas is defined as a substance that has no well defined boundaries but diffuses rapidly into to fill any container in which it is placed.

an ideal gas is one that obeys all the assumptions of the kinetic theory of gases under all conditions of temperature and pressure.

Real gases differ from ideal gases because of:

1)force of repulsion and attraction between the molecules

2) the volumes of the molecules are not negligble.

Brownian Motion is the random movement of tiny particles suspended in a fluid.


Boyles Law states that at a constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure.

Charles Law states that at a constant pressure, the volume of a fixed mass of gas is proportional to its temperature when measured on the KELVIN SCALE.

Avogadros Law states that equal volumes of gases contain equal numbers of molecules under the same conditions of temperature and pressure.

Gay Lussacs Law states that in a reaction between gases, the volumes of the reacting gases and the volumes of any gaseous products are in the ratio of small whole numbers provided that the volumes were measured under the same temperature and pressure.


Co + 273 = Kelvin(K)

1KPa = 1000 Pa = 1000N/m2

1 litre = 1000cm3

S.T.P ( standard temperature and pressure) = 101Kpa and 0oC

At S.T.P one mole of any gas occupies 22.4 Litres of space + refer to notes on the Mole Concept for the complete mole picture.

BL:p 1V 1= k=p 2 V 2 CGL:p 1 V1/T1 = k = p 2V 2/T 2

p-pressure, t-temp, v-volume, n=molar mass, R is a constant that you are given on the day of the exam(8.31)

CL:V 1/T 1 = k=V 2/T 2 Ideal Gas Equation: pV = nRT

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