Gas Laws

In gases, there are three different variables, which are pressure, temperature and volume, and all of these components are dependent on each other.

If one of these components is fixed and any of the other two are changed, the last component would also change with respect to the variable component. This can be seen in the following three relationships:

If the temperature is kept constant the relationship between Volume and Pressure would be an inversely proportional relationship, showing that when one component is increased, the other one would decrease. This can be seen in the following relationship:

gases 2.5

If the volume is kept constant the relationship between Pressure and temperature would be a directly proportional relationship, indicating that one component increases, the other would decrease. This can be seen in the following relationship:

gases 4

Which can also be written as:

gases 5

If the pressure is kept constant the relationship between volume and temperature would be a directly proportional relationship, indicating that one component increases, the other would decrease. This can be seen in the following relationship:

gases x

Which can also be written as:

gases y

On combining these three equations two very important equations can be derived:

gases 6

and

gases 7

The units for each of Pressure, Volume and Temperature are Pa, m3 and K respectively.

Gay Lussac’s Law

Another important concept is the Gay Lussac’s Law of combining of volumes which states that when two different volumes are mixed the ratio of these two volumes would be proportional to the original ratio under the same pressure and temperature. If these two gases react the volume ratio between the original reactants and the final products would then depend on the stoichiometry of the reaction.

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