Gas Equation




According to Boyle’s law

V ∝   1/P                                   (T is constant)

According to Charle’s Law

V ∝   T                                      (P is constant)

Combining these two laws,

V ∝   T/P

PV   ∝  T


PV/T  = constant

K is a constant


For one mole of gas, the constant K is replaced by R. Since the value of R is same for each gas, it is known as universal gas constant

PV = RT ———gas eq.

P=Pressure of gas

V= Vol. of 1 mole of gas

T= Temperature in Kelvin (Absolute Temp.)

R= Universal gas constant

Gas Eq. for n mole of gas,

PV =nRT      ( Gas  equ. )

n= no. of moles of Gas

Above gas eq. may be written as,

n = w/m

PV = w/m (RT) ——–gas equation

w=weight or mass in grams

m=molecular weight of gas

density of gas d = w/v

P = DRT/m                            gas equ.