# Gas Laws.

## Presentation on theme: "Gas Laws."— Presentation transcript:

Gas Laws

Charles’ Law V: volume, mL, cm3, L, dm3
T: temperature, Kelvin (Tc + 273K)

Example Problem #1 A. When 400mL of hydrogen at 25oC are heated to 290oC, what will its volume reach? B. A sample of gas at 40mL is heated to 40oC and increases to 750mL. What is the initial temperature of the gas?

Boyle’s Law P: Pressure, mmHg, torr, atm, Pa, kPa
V: volume, cm3, mL, dm3, L

Example #2 A. A 1200mL sample of oxygen at 700mmHg is expanded to 5.9L. What is the pressure at the larger volume? B. A 25mL sample of ammonia gas at 400torr is placed under a pressure of 5590torr. What is the new volume?

Gay-Lusaac’s Law P: Pressure, atm, Pa, kPa, mmHg, torr
T: Temperature, in Kelvin

Example #3 A. A sample of gas at 450torr at 30oC is heated to 75oC. What pressure will it reach? B. A sample of nitrogen at 50oC and 2.2atm is cooled until the pressure reaches 0.8atm. What temperature did the gas reach?

Combined Gas Law All the letters are the same as before.

Example #4 A. A sample of gas at 20oC and 800torr has a volume of 475mL. What is its volume at 75oC and 890torr? B. A sample of gas at 35oC and 90mmHg has a volume of 97mL. At what temperature will it reach 300mmHg with a volume of 40mL?

Ideal Gas Law P: pressure in atm V: volume in L n: moles
R: (gas law constant) T: temperature in K 1 atm = 760 torr = 760 mmHg=101.4kPa

STP STP stands for standard temperature and pressure. If a problem says a gas is at STP it is actually giving you two pieces of information: P = 1atm = 760torr = 760mmHg=101.4kPa T = 273K

Example #5 A. What volume will 50g of chlorine occupy at 30oC and 850torr? B. What pressure will 27g of carbon dioxide exert at 45oC in a 1200mL container? C. What mass of oxygen will occupy 30mL at STP? D. What temperature will 3g of hydrogen exerts 40kPa of pressure in a 90mL container?

Funny Gas Effect.

Dalton’s Law PT = P1 + P2 + P3… PT: total pressure
P1, P2, P3: partial pressures of each gas present.

Example #6 A. The total pressure in a flask is 5atm. If the flask contains 3 gases and the partial pressure of oxygen is 0.85atm, and nitrogen is 1.3atm, what is the partial pressure of the third gas in the flask?