NAME: ______DATE: ______PERIOD: ______

Notes on Gas Laws

(See PowerPoints on Boyle’s Law, Charles’ Law, and Gay-Lussac’s Laws)

Boyle’s Law

  • ______vs. ______
  • Discovered by Irish chemist, Robert Boyle; states that the volume of a fixed mass of gas ______with pressure at a constant temperature.
  • Used a ______tube to experiment with varying pressures and their effects on the volume of an enclosed gas. Pressure is caused by moving molecules ______container walls.
  • k = V x P where “k” is a ______for a certain sample of gas that depends on the mass of the gas and the temperature.
  • As one increases, the other decreases. This is a(n) ______relationship.
  • If we have a set of new conditions for the same sample of gas, they will have the same “k” so we can set up a ratio: P1V1 = k = P2V2 OR P1V1 = P2V2
  • What kind of graph is V vs. P? ______

Draw a graph that represents this relationship:

Example: Consider a 1.53-L sample of gaseous SO2 at a pressure of 5.6 x 103 Pa. If the pressure is changed to 1.5 x 104 Pa at constant temperature, what will be the new volume of the gas? Show your work!

Charles’ Law

  • ______vs. ______
  • Discovered by French physicist, Jacques Charles, in 1787; the first person to fill a balloon with ______and make a solo balloon flight.
  • States that the volume of a fixed mass of gas varies directly with temperature at a constant pressure.
  • As ______increases the volume increases.
  • V = kT or k = V/T …where “k” is a constant for a certain sample of gas that depends on the mass of gas and its pressure.
  • If we have a set of new conditions for the same sample of gas, they will have same “k” so we can set up the ratio: V1/T1 = k = V2/T2 OR V1/T1 = V2/T2
  • To use Charles’ Law we need a temperature scale that has no negative values; this is the Kelvin scale which starts at -273.15 ° C = absolute zero = 0 Kelvin (K)
  • What kind of graph is T vs. V? ______

Draw a graph that represents this relationship:

Example: A gas with a volume of 600 mL has a temperature of 30 0C. At constant pressure the gas is heated until the gas expands to 1,200 mL. What is the new temperature of the gas if the pressure remains constant? (Convert: 300 C + 273 = 303 K) Show your work!

Gay-Lussac’s Gas Law

  • ______vs. ______
  • States that if the ______of a gas is increased and the volume is held constant, the pressure of the gas will also ______.
  • Gay-Lussac's Law is a ______mathematical relationship. When one increases, the other also increases.
  • k = P ÷ T …where “k” is a constant for a certain sample of gas that depends on the mass of gas and its pressure. As with the other laws, the exact value of k is unimportant in our context.
  • What kind of graph is T vs. P? ______

Draw a graph that represents this relationship:

  • If we have a set of new conditions for the same sample of gas, they will have same “k” so we can set up the ratio: P1 ÷ T1 = P2 ÷ T2

Example: 10.0 L of a gas is found to exert 97.0 kPa at 25.0°C. What would be the required temperature (in Celsius) to change the pressure to standard pressure (101.3kPa)? (Remember to change 25.0°C to 298.0 K.) Show your work!

Combined Gas Law

  • Boyle’s Law, Charles’ Law, and Gay-Lussac’s Law can be combined to create a “Combined Gas Law.”
  • The Combined Gas Law equation is: P1V1 / T1 = P2V2 / T2
  • P = Pressure V = ______T = Temperature