characteristics of gas -  

• possible for substance to coexist as solid, liquid, and gas at the same time
• vapor - gaseous form of a substance normally existing as liquid/solid
• expands to fill the container it’s in (gas volume = volume of container)
• pressure added to gas >> gas gets compressed easily >> volume decreases
• form homogeneous mixtures (regardless of type of gases involved)

pressure - force acted upon a given area

• P = F/A
• newton (N) - SI unit for force, kg-m/s2
• pascal (Pa) - SI unit for pressure, N/m2
  • kPA = 1000 Pa
  • bar = 105 Pa, approximate atmospheric pressure at sea level
• barometer - invented by Evangelista Torricelli, measures atmospheric pressure
  • manometer - used to measure pressure of liquids/gases, similar to barometer
• standard atmospheric pressure = pressure needed to support column of mercury 760 mm high
  • atm = 760 mm Hg, 760 torr = 1.01325 x 105 Pa = 101.325 kPa
  • 1 torr = 1 mm Hg

Boyle’s Law - pressure-volume relationship

• volume of gas (at constant temperature) inversely proportional to pressure
• P1V1 = P2V2

Charle’s Law - temperature-volume relationship

• volume of gas (at constant pressure) directly proportional to temperature
• V1/T1 = V2/T2

Avogadro’s Law - quantity-volume relationship

• law of combining volumes - at given pressure/temperature, volumes of reacting gases exist in simple ratios
• equal volumes of gases at same temperature/pressure have equal numbers of molecules
• volume of gas (at constant pressure/temperature) directly proportional to number of moles of gas
• V = constant x n