IDEAL GAS LAW &

REAL GASES

IDEAL GAS LAW:

Used when the amount of gas varies

Can be used to calculate the number of moles of gas

Needed in the equation

R = 8.31 (L x kPa)/ (K x mol)

R = 0.0821 (L x atm)/ (K x mol)

When to use it? Ideal Gas Law Constant

IDEAL GAS LAW EQUATION:

PV = nRT

PRACTICE PROBLEM

When the temp of a rigid hollow sphere containing 685 L of helium gas is held at 621 K, the pressure of the gas is 1.89 x 103 kPa. How many moles of helium does the sphere contain?

REAL GASES

Do not always follow the ideal gas law

Due to the fact that gas particles DO have volume & can be attracted to each other

Differ most at low temps & high pressures