Note
It is founded that the value of constant is dependent on the enclosed mass of gas for a given gas
and is also found to differ for different gases of 1 unit of mass. However, it is found that if 1 mol. mass
( Mass numerically equivalent in gm to molecular weight, e.g., 2 gm for
H_{ 2}, 32 gm for O_{2 }, 28 gm
for N_{2 }, etc.) of any ideal gas is chosen then the value of the constant is same for all gases. This
universal constant (same for all gases) is denoted usually by 'R' and is called the universal gas constant.
The ideal gas equation therefore is normally written as
where n = number of molecules.
The no. of molecules is defined as, the ratio of actual mass of gas M to its molecular weight
(M_{o})
If m is the mass of each molecule of a given gas and N is the no.of molecules that make up the
mass = M; whereas N_{o}= Avogadro's no. = Number of molecules in 1 mole of the gas (any gas), then M
= mN & M_{o} = mN_{o}.

Index
12.1 Solids
12.2 Liquids
12.3 Gases
12.4 Gas Laws
12.5 Equation of State :Ideal Gas Equation
12.6 Kinetic Theory of Ideal Gases
Chapter 13
