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# Gas laws

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### Gas laws

1. 1. GAS LAWS Quantitatively measure the relationship between Pressure,Volume andTemperature.
2. 2. PRESSURE: is created by gas particles hitting a surface.
3. 3. BOYLE’S LAW pV = constant p1V1=p2V2 Assumes temperature is constant Pressure ↑,Volume↓ Pressure↓,Volume↑
4. 4. PRACTICE PROBLEM: Bacteria produce methane gas in sewage-treatment plants.This gas is often captured or burned. If a bacterial culture produces 60.0 mL of methane gas at 700.0 mm Hg, what volume would be produced at 760.0 mm Hg? p1V1=p2V2 700 mmHg x 60.0 mL = 760 mmHg xV2 = 55.3 mL of methane gas
5. 5. PRACTICE PROBLEM Hospitals buy 400-L cylinders of oxygen gas compressed at 150 atm.They administer oxygen to patients at 3.0 atm in a hyperbaric oxygen chamber.What volume of oxygen can a cylinder supply at this pressure? p1V1=p2V2 150 atm x 400 L mL = 3.0 atm xV2 = 20,000 L of oxygen
6. 6. CHARLES’ LAW V/T = constant V1/T1 =V2/T2 Assumes pressure is constant. Temp must be measured in Kelvin (K=˚C + 273) V ↑ T↑ V↓ T↓
7. 7. PRACTICE PROBLEM A balloon is filled with 3.0 L of helium at 310 K.The balloon is placed in an oven where the temperature reaches 340 K.What is the new volume of the balloon? V1/T1 =V2/T2 3.0L/310K =V2/340K V2= 3.3 L
8. 8. PRACTICE PROBLEM A 25 L sample of nitrogen is heated from 110 ˚C to 260 ˚C. What volume will the sample occupy at the higher temperature? K=˚C + 273 T1 = 110 ˚C + 273 T1 = 383 K T2 = 260˚C + 273 T2 = 533 K V1/T1 =V2/T2 25L/383K = V2/533K V2= 35 L
9. 9. COMBINED GAS LAW PV/T = constant P1V1/T1 = P2V2/T2
10. 10. PRACTICE PROBLEM A gas that has a volume of 28 L, a temperature of 45˚C, and an unknown pressure has its volume increased to 34 L and its temperature decreased to 35˚C. If I measure the pressure after the change to be 2.0 atm, what was the original pressure of the gas? P1 = ? V1 = 28L T1 =45˚C + 273 = 318K P2 = 2.0 atm V2 = 34 L T2 = 35˚C + 273 = 308 K P1V1/T1 = P2V2/T2 (P1x 28L)/318K = (2.0atm x 34L)/308K P1 = 2.51 atm
11. 11. PRACTICE PROBLEM I have an unknown volume of gas at a pressure of 5.0 x 104 Pa and a temperature of 325 K. If I raise the pressure to 1.2 x 105 Pa, decrease the temperature to 320 K, and measure the final volume to be 4.8 x 104 cm3, what was the initial volume of the gas? P1V1/T1 = P2V2/T2 (5.0 x 104 Pa xV1)/325K = (1.2 x 105 Pa x 4.8 x 104 cm3)/320K V1 = 1.17x1013cm3