III. Gas Laws •  A sample of gas can be physically described by its pressure (P), temperature (T), volume (V), and amount of moles (n). •  If you know any 3 of these variables, you know the 4th. •  We look at the history of how the ideal gas law was formulated. IV. Volume and Pressure – Boyle’s Law  The volume of a gas is inversely related to pressure, i.e. if P increases, V decreases. IV. Volume and Temperature – Charles’s Law •  The volume of a gas is directly related to its temperature, i.e. if T is increased, V will increase. IV. The Combined Gas Law •  Boyle’s and Charles’s Laws can be combined into a convenient form. IV. Volume and Moles – Avogadro’s Law •  The pressure of a gas is directly related to the number of moles of gas, i.e. if n increases, V will increase. IV. The Ideal Gas Law •  The ideal gas law is a combinaKon of the combined gas law and Avogadro’s Law. R = 0.082058 L atm/K mole
V. Other Uses of Ideal Gas Law •  The ideal gas law can be used to find other physical values of a gas that are not as obvious.   gas density, d = mass/volume   gas molar mass, MW = mass/mole   stoichiometry, via moles and a balanced equaKon VII. Why Do Gas Laws Work So Well? •  Recall that the gas laws apply to any gas – the chemical idenKty is not important. •  Gas parKcles only interact when they collide. Since this interacKon is so short, chemical properKes don’t have Kme to take effect!! VII. Explaining Boyle’s Law VII. Explaining Charles’s Law VII. Explaining Avogadro’s Law