Ideal Gas law

The Ideal Gas law interrelates pressure, temperature, volume and number of moles of a gas sample. This law integrates the laws of Boyle, Charles and Avogadro.

Boyle's law : V ∞ 1/P
Charles' law: V ∞ T
Avogadro's law: V ∞ n

Combining these three laws will yield to a more general equation:

PV = nRT

where R is the gas constant:

R = 0.0821 L.atm / mol.K

Sample Problem:

What volume will1.27 moles of Helium gas occupy at STP?

Given:

P = 1 atm

V = ?

n = 1.27mol

R = 0.0821 L.atm / mol.K

T = 25 ºC + 273 = 298K

Solution:

PV = nRT

(1 atm)V = (1.27mol)(0.0821 L.atm/mol.K)(298K)

V = (1.27mol)(0.0821 L.atm/mol.K)(298K)

(1 atm)

V = 31.07 Liters

Exercises:

1. How many moles of gas are contained in a 50.0L cylinder at a pressure of 100.0atm and a temperature of 35.0ºC?
2. What would be the volume occupied by a 1mole gas at STP?