Ideal Gas & Ideal Gas Law

What is an Ideal Gas ????

An Ideal Gas or a Perfect Gas is the one which is composed of a set of randomly-moving, non-interacting point particles.

An Ideal Gas obeys Boyle's Law and Charle's Law.

Practically ideal gas does not exist,But many common gases exhibit behaviour very close to that of an Ideal Gas at ambient temperature and pressure.

Ideal Gas Law :-

A law relating the pressure, temperature , and volume of an ideal gas is called as Ideal Gas Law . It was first stated by a Physicist and Engineer Benoit Paul Emile Clapeyron in 1834. The ideal gas law predicts the state of a gas at a given pressure and temperature.

Mathematically the Ideal Gas Law can be stated as :-

PV = nRT

where,

P is the absolute pressure ,

V is the volume of the vessel ,

n is the number of moles of gas ,

R is the Universal Gas constant, and in accordance with it's name it is same for all gases &

T is the absolute temperature in Kelvin.

Ideal Gas Law is derived as follows :-

According to Boyle's Law for a given mass of an ideal gas,the product of pressure and volume is constant,i.e.,

P x V = constant

Also, according to Charle's Law for a given mass of an ideal gas, the ratio of the volume to temperature is constant,i.e.,

V/T = constant

Combining the above two laws,we get,

P x V/T = constant

The constant in the above equation is denoted by R and is known as Universal Gas Constant.

Thus we can say,

PV = RT

Now, for 'n' kilomoles of an Ideal Gas,the above equation can be written as ,

PV = nRT

This above equation is the ultimate mathematical form of Ideal Gas Law.

The Ideal Gas Law states 3 facts :-

i) Volume of a gas is directly proportional to the number of moles

ii) Volume of a gas is directly proportional to absolute temperature

&

iii) Volume of a gas is inversely proportional to the pressure.