The Ideal Gas Law

1
The Ideal Gas Law

• Objectives
• 7.0 Explain the behavior of ideal gases in terms
  of pressure, volume, temperature, and number of
  particles using Charles's law, Boyle's law,
  Gay-Lussac's law, the combined gas law, and the
  ideal gas law.
• 6.0 Solve stoichiometric problems involving
  relationships among the number of particles,
  moles, and masses of reactants and products in a
  chemical reaction.

2
Intro

• What will happen to the pressure in a tire as air
  is added, if the volume and temperature of the
  tire do not change?
• So the amount of gas (moles) and the pressure
  both change.
• Remember
• Combined Gas Law P1V1 P2V2
• T1
  T2

3
Ideal Gas Law

• Since the ratio remains the same, then we can say
  it is constant. We call the constant k.
• k is a constant based on the amount of gas (n)
  present, where k nR. (R is an experimentally
  determined constant, called the ideal gas
  constant, and equal to 0.0821 L-atm/mol-K.
• Ideal gas law equation PVnRT

4
What is an Ideal Gas?

• A gas that follows all the gas laws
• When do gases not follow the gas laws?
• Gases tend not to behave ideally under very
  high pressures and low temperatures, as there is
  more inter-particular interactions.
• Also, polar particles (like water vapor) are more
  attracted to each other because of their partial
  charges.
• Large particles interact more.

5
Applying the Ideal Gas Law

• PVnRT
• What is n?
• How can n be used to find the mass of a gas
  present?
• From stoichiometry, what else can be determined
  from n? How??????
• Substitutions in the ideal gas equation
• n mass (m)/molar mass (M)
• Rearrange the formula to solve for M.
• Density (D) ?????

6
Examples Assignment

• Examples p.437 (41, 45) and p.438 (46, 50)
• Other Practice Problems can be used to practice
  and make sure you know how to solve problems.
• Assignment
• Section Assessment p. 439 (53, 55)
• 449 97-100