You will need a partner as well as a calculator The Gas Laws You will need a partner as well as a calculator

Ideal Gas Law PV = nRT Boyle’s Law P1V1 = P2V2 Combined Gas Law P1V1/T1 = P2V2/T2

Pressure Pressure (P): The force of gas molecules as they hit the sides of the container in which they are placed.    Units = Atmospheres (atm) StandardTemperaturePressure = 1atm

Temperature StandardTemperaturePressure = 273 K Temperature (T): A measurement of the amount of energy that molecules have. The higher the energy, the higher the temperature.   Common units of temperature: Kelvin (K): The ONLY units that can be used when doing numerical problems with gases. *Degrees Celsius (0C): Must be converted to Kelvin before doing problems (by adding 273). StandardTemperaturePressure = 273 K

Volume Volume (V): The amount of space in which a gas is enclosed.   The most commonly used unit of volume is liters (L).

Which tank contains the greatest number of particles? Number of particles = pressure x volume 10 atm 1 atm 40 atm 25 atm 30 L 60 L 45 L 15 L A B C D

Ideal Gas Law Avogadro’s law: One mole of every gas has the same volume. (22.4 L) STP = standard temperature & pressure Standard temperature = 273 K Standard pressure = 1 atm All gases behave the same at the same temperature, volume and pressure. H2O(g), CO2(g), O2

Ideal gas law: PV = nRT P = pressure (in atm) V = volume (L) n = number of (moles)  R = ideal gas constant 0.0821 L•atm/mol•K T = temperature (Kelvin) = (oC + 273)

“We Do” If I have 10 liters of a gas at a pressure of 1.5 atm and a temperature of 250 C, how many moles of gas do I have? P = 1.5 atm V = 10 L n = ? moles R = 0.0821 (always this #) T = 25oC+ (273) = 298 K

PV=nRT (P x V) = (n x R x T) 1.5 x 10 = n x 0.0821 x 298 Divide both sides by 24.47 so “n” by itself n = 0.613 moles

“You Do” If I have 23.5 moles of gas at a temperature of 67.89 oC, and a volume of 88.98 liters, what is the pressure of gas? P = V = n = R = 0.0821 (always this #) T = ___oC+ (273) =

Boyle’s Law P1V1 = P2V2 ****Remember that temperature needs to be in Kelvin (oC = 273K)**** P1 = First Pressure V1 = Frist Volume P2 = Second Pressure V2 = Second Volume

“We Do” P1V1 = P2V2 A high-altitude balloon contains 30.0 L of He has at 10.3 atm. What is the new volume when the balloon rises to an altitude where the pressure is only 2.3 atm? P1 = V1 = P2 = V2 =

P1V1 = P2V2 (10.3 atm) (30.0 L) = (2.3 atm) ( V2)

“You Do” P1V1 = P2V2 A gas with a volume of 4.02 L at a pressure of 2.31 atm is allowed to expand to 12.89 L. What is the new pressure of the gas? P1 = V1 = P2 = V2 =

Combined Gas Law P1V1 = P2V2 T1 T2 P1 = First Pressure ****Remember that temperature needs to be in Kelvin (oC = 273K)**** P1 = First Pressure V1 = Frist Volume T1 = First Temperature P2 = Second Pressure V2 = Second Volume T2 = Second Temperature

“We Do” P1V1/T1 = P2V2/T2 If I initially have a gas at a pressure of 1.3 atm, a volume of 24.6 liters and a temperature of 214K, and then I raise the volume to 46.0 L and increase the temperature to 286 K, what is the new pressure of the gas? P1 = P2 = V1 = V2 = T1 = T2 =

P1V1/T1 = P2V2/T2 (1.5 atm)(24.6 L) = (P2)(46.0 L) 214 K 286 K 0.172 atm L/K = (P2) (0.161 atm/K) P2 = 1.75 atm

“You Do” P1V1/T1 = P2V2/T2 If I have 23.5 L of gas held at STP, what is the volume of gas if I increase the pressure to 45.2 atm and increase the temperature to 26.78 oC? P1 = P2 = V1 = V2 = T1 = T2 =