Summary

Videos

References

Among the known 117 elements, only 11 elements are in the gaseous state at room temperature and pressure. The gaseous state is the simplest form of matter.

**Properties:**

• Gases have no definite shape and volume and hence assume the volume and shape of the container.

• Gases are highly compressible.

• Gases exert equal pressure in all directions.

• Gases intermix equally and completely in all proportions.

• Gases have lower density than solids and liquids.

The study of the behavior of gases has led to some important generalisations called the Gas Laws.

The four main laws are Boyle's Law, Charles' Law, Gay Lussac's Law and Avogadro's Law.

**Boyle's Law:**

Boyle's Law expresses the relationship between volume and pressure.

According to this law pressure is inversely proportional to volume at constant temperature.

P ∝ 1/V (at constant T and n)

P = K/V

Graph giving the relationship between pressure and volume

**Charles' Law:**

Charles' Law expresses the relationship between volume and temperature.

According to this law volume is directly proportional to temperature at constant pressure.

V∝T,

V = KT at constant pressure.

Graph giving the relationship between volume and temperature at different pressures.

**Gay Lussac's Law: **

Gay Lussac's Law expresses the relationship between pressure and temperature.

According to this law pressure is directly proportional to temperature at constant volume.

P ∝ T

P = kT k = Proportionality constant

Graph giving the relationship between pressure and temperature at different volumes.

**Avogadro's Law: **

Avogadro's Law expresses the relationship between volume and number of particles.

According to this law 'at constant temperature and pressure, the volumes of all gases is directly proportional to the number of gas particles'.

V ∝ n

V = nk

Among the known 117 elements, only 11 elements are in the gaseous state at room temperature and pressure. The gaseous state is the simplest form of matter.

**Properties:**

• Gases have no definite shape and volume and hence assume the volume and shape of the container.

• Gases are highly compressible.

• Gases exert equal pressure in all directions.

• Gases intermix equally and completely in all proportions.

• Gases have lower density than solids and liquids.

The study of the behavior of gases has led to some important generalisations called the Gas Laws.

The four main laws are Boyle's Law, Charles' Law, Gay Lussac's Law and Avogadro's Law.

**Boyle's Law:**

Boyle's Law expresses the relationship between volume and pressure.

According to this law pressure is inversely proportional to volume at constant temperature.

P ∝ 1/V (at constant T and n)

P = K/V

Graph giving the relationship between pressure and volume

**Charles' Law:**

Charles' Law expresses the relationship between volume and temperature.

According to this law volume is directly proportional to temperature at constant pressure.

V∝T,

V = KT at constant pressure.

Graph giving the relationship between volume and temperature at different pressures.

**Gay Lussac's Law: **

Gay Lussac's Law expresses the relationship between pressure and temperature.

According to this law pressure is directly proportional to temperature at constant volume.

P ∝ T

P = kT k = Proportionality constant

Graph giving the relationship between pressure and temperature at different volumes.

**Avogadro's Law: **

Avogadro's Law expresses the relationship between volume and number of particles.

According to this law 'at constant temperature and pressure, the volumes of all gases is directly proportional to the number of gas particles'.

V ∝ n

V = nk