Pressure and Temperature

The Effects of Increasing the Temperature of a Sample of Gas at Constant Volume

Temperature and Pressure What would happen to the pressure in a sealed container (i.e. volume remains constant) if heat is added? Graph the following data: Temperature (K) Pressure (kPa) 129 111 301 242 403 323 501 429 601 517 704 613

Pressure is directly proportional to temperature (in Kelvins) P  T Pressure increases proportionally as temperature increases, provided volume and amount remain constant. Pressure is directly proportional to temperature (in Kelvins) P  T A direct relationship P = kT P = k T P1 = P2 T1 T2

A gas cylinder with a pressure of 1000kPa at 25°C is placed in a boiling water bath. What will the new pressure reading be? P1 = 1000kPa T1 = 25 + 273 = 298K P2 = ? T2 = 100 + 273 = 373K P2 = 1000kPa x 373 K 298 K P2 = 1252 kPa P1 = P2 T1 T2

Combined Gas Law

Boyle’s Law: PV = K P1V1=P2V2 Charles’ Law: V =K V1/T1=V2/T2 T Pressure-Temperature Law: P = K P1/T1=P2/T2 T

Combined Gas Law P1V1 = P2V2 T1 T2 An aerosol can with a volume of 325 mL at 12°C and a pressure of 250 kPa is released into a room at 25°C and 101 kPa. Determine the new volume? P1= 250 kPa P2 = 101 kPa V1 = 325 mL = 0.325L V2 = T1 = 12 + 273 = 285K T2 = 25 + 273 = 298 K V2 = 0.325L x (250 kPa)(298 K) (101 kPa) (285K) V2 = .841L

Example An inflated baloon has a volume of 6.0 L at sea level (1.0 atm) and is allowed to scend in altitude until the pressure is 0.45 atm. During ascent the temperature of the gas falls from 22 to -210C. Calculate the volume of the baloon at its final altitude.

Example A 0.50 mol sample of oxygen gas is confined at 0oC in a cylinder with a movable piston. The gas has an initial pressure of 1.0 atm. The gas is then compressed by the piston so that its final volume is half the initial volume. The final pressure of the gas is 2.2 atm What is the final temperature of the gas?