1. I DEAL GAS LAW & R EAL GASES

2. I DEAL G AS L AW : 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

3. I DEAL GAS LAW EQUATION : PV = nRT

4. P RACTICE P ROBLEM 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 10 3 kPa. How many moles of helium does the sphere contain?

5. R EAL 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