# Charle's Law|Boyle's law|Ideal Gas Law

## 1. Gas Laws

Gas laws are study of any two of quantities like pressure, volume and temperature, when the third is kept constant

A. Boyle's law

• "At constant temperature, the volume of a given mass of gas is invesely propertional to pressure." Thus
V ∝ 1/P
Or,                PV = constant               (1)
• If P1, V1are initial pressure and volumes and P2, V2be final values then,
P1V1= P2V2
• Graph between P and V at temperature T1 and T2 such that T1<T2 are shown below,

• Graph above shows that Boyle's law is strictly not obeyed by gases at all values of P and T but it obeys this law only at low pressure and high temperature i.e., at law density
B. Charle's Law
• Charle's Law is stated as follows :
"When pressure of a gas is constant the volume of a given mass of gas is directly proportional to its absolute temperature".
V/T = Constant               (2)
• Graph between V and T is

This graph shows that experimental graph deviates from straight line. Theoritical and enperimental graphs are in agreement at high temperature.

## 2. Ideal gas equation

• We can combine Boyle' law eqn (1) and charle' law eqn (2) in to a single eqn i.e.,
PV/T = Constant          (3)
If n moles is the mass of gas then we write
PV = nRT               (4)
where, n is number of moles of gas, R=NAKB is the universal constant known as gas constant and T is the absolute temperature.
• A gas satisfying eqn (4) at all values of presserves and temperatures is said to be an ideal gas
now no of moles of gas
n = m/M = N/NA
where
m - mass of gas containing N molecules
M - molar mass