# The Gas Laws 11.2.

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The Gas Laws 11.2

Boyle’s Law Boyle’s Law – the volume of a fixed mass of gas varies inversely with the pressure at constant temp. PV = k You can relate 2 different gases w/ k P1V1 = P2V2

Practice A sample of O2 gas has a vol of mL when it’s P is atm. What will the vol of the gas be at a P of atm if the T remains constant? Make sure both P and V units are the same!

Practice A balloon filled with He gas has a vol of 500 mL at a P of 1 atm. The balloon is released and reaches an altitude of 6.5 km, where the P is 0.5 atm. If the T has remained the same, what volume does the gas occupy at this height?

Temperature Absolute zero – the T of °C is given a value of 0 in the Kelvin scale. K = °C Charles’ Law = the vol of a fixed mass of gas at constant P varies directly with the Kelvin Temp

Charles’ Law V = kT V = k T V1 = V2 T1 = T2

Practice A sample of neon gas occupies a volume of 752 mL at 25°C. What V will the gas occupy at 50°C if the P is constant? A sample of N2 gas is contained in a piston w/a freely moving cylinder. At 0°C, the V of the gas is 375 mL. To what T must the gas be heated to occupy a V of mL?

Gay-Lussac’s Law The P of a fixed mass of a gas at constant V varies directly with the Kelvin T P = kT P = k T Set K equal to get… P1 = P2 T1 = T2

Practice The gas in a container is at a P of atm at 25°C. Directions on the container warn the user not to keep it in a place where the T exceeds 52°C. What would the P be at 52°C?

Practice At °C, the pressure of a sample of nitrogen is 1.07 atm. What will the pressure be at 205 °C, assuming constant volume. A sample of He gas has a P of atm at 22 °C. At what Celsius Temp will the He reach a P of 2.00 atm, assuming constant V.

The Combined Gas Law Combines Charles’, Boyle’s, and G-L CGL – expresses the relationship b/t P, V, and T of a fixed amt of gas PV = k P1V1 = P2V2 T T T2 T must be in Kelvin!!!!!

Practice A helium Balloon has a volume of L at 25°C and 1.08 atm. What V will it have at atm & 10.0°C? A mL gas sample at STP is compressed to a V of mL, and the T is increased to 30.0 °C. What is the new P of the gas in Pa? Complete S.R. on page 375 # 1-5 