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