Chapter 13 The Gas Laws

Rates of Effusion Graham’s Law of Effusion:

Rates of diffusion Depends mainly on mass of particles involved Grahams law allows us to compare rates of diffusion of two gasses

Ammonia has a molar mass of 17 Ammonia has a molar mass of 17.0 g/mol, hydrogen chloride has a molar mass of 36.5 g/mol. What is the ratio of their diffusion rates?

What is the molar mass of a gas that takes four times as long to effuse as hydrogen?

Gas Pressure Pressure = force per unit area Smaller area = more pressure Air pressure – pressure of the atmosphere 1 atm 760 mm Hg 101.3 kPa

Dalton’s law of partial pressures: Total pressure of a mixture of gasses is equal to the sum of the pressures of all of the gasses in the mixture P1 + P2 + P3…=Ptotal

A mixture of oxygen, carbon dioxide, and nitrogen has a total pressure of 0.97 atm. What is the partial pressure of O2 if the partial pressure of CO2 is 0.70 atm and the partial pressure of N2 is 0.12 atm?

3 factors affecting gases Temperature Kelvin = Celsius + 273 Volume L mL Pressure kPa atm mmHg Values for pressure units

Ping pong ball in hot water video

Boyles Law TEMPERATURE CONSTANT Pressure and volume are inversely related P1 x V1 = P2 x V2 Relate to KMT

A diver blows a 0. 75 L air bubble 10 m under water A diver blows a 0.75 L air bubble 10 m under water. As it rises to the surface, the pressure goes from 2.25 atm to 1.03 atm. What ill be the volume of the air in the bubble at the surface?

The volume of a gas at 99. 0 kPa is 300. 0 mL The volume of a gas at 99.0 kPa is 300.0 mL. if the pressure is increased to 188 kPa, what will be the new volume?

Charles’s Law PRESSURE CONSTANT Flexible container Volume and temperature are directly related Temperature must be in K! Relate to KMT

A helium balloon in a closed car occupies a volume of 2. 32 L at 40 A helium balloon in a closed car occupies a volume of 2.32 L at 40.0 oC. If the car is parked on a hot day and the temperature inside rises to 75.0 oC what is the new volume of the balloon?

A gas at 89 oC occupies a volume of 0. 67 L A gas at 89 oC occupies a volume of 0.67 L. At what Celsius temperature will the volume increase to 1.12 L?

Gay-Lussac’s Law VOLUME CONSTANT Pressure and Temperature are directly related Temperature must be in K! Relate to KMT

The pressure of the oxygen gas inside a canister is 5. 00 atm at 25 The pressure of the oxygen gas inside a canister is 5.00 atm at 25.0 oC. The canister is located at a camp high on Mount Everest. If the temperature there falls to -10.0 oC, what is the new pressure inside the canister?

Helium gas in a 2. 00 L cylinder is under 1. 12 atm pressure. At 36 Helium gas in a 2.00 L cylinder is under 1.12 atm pressure. At 36.5 oC that same gas sample has a pressure of 2.56 atm. What was the initial temperature of the gas in the cylinder?

The Combined Gas Law The three gas laws discussed can be combined into a single gas law.

A gas at 110 kPa and 30.0oC fills a flexible container with an initial volume of 2.00 L. If the temperature is raised to 80.0 oC and the pressure increases to 440 kPa, what is the new volume?

A sample of air in a syringe exerts a pressure of 1.02 atm at 22.0 oC. The syringe is placed in a boiling water bath at 100.0 oC. The pressure is increased to 1.23 atm by pushing the plunger in, which reduces the volume to 0.224 mL. What was the initial volume?

The Ideal Gas Law Relates number of particles, pressure, temperature, and volume Avogadro’s principle – equal volumes of gases at the same temperature and pressure contain equal numbers of particles Talk about 1st part of paragraph

Molar volume of a gas is the volume that 1 mol occupies at STP 1 mol of gas = particles Molar volume of a gas is the volume that 1 mol occupies at STP STP = 1 mol = 22.4 L of gas

How many moles of carbon dioxide gas are in a 1.0 L balloon? What volume will 9.22 g of H2 gas occupy at STP?

The Ideal Gas Law PV = nRT R = 8.31 L*kPa/mol*K R = 0.0821 L*atm/mol*K Units for each variable

Calculate the number of moles of ammonia gas contained in a 2 Calculate the number of moles of ammonia gas contained in a 2.0L vessel at 300.0 K with a pressure of 1.50 atm

What is the volume of a 0. 323 mol sample of a gas at 265 K and 0 What is the volume of a 0.323 mol sample of a gas at 265 K and 0.900 atm?

How many moles of a gas are in 2.50 L of gas at STP?

Real vs. Ideal Gas Ideal gases follow the assumptions of the kinetic-molecular theory Particles take up no space Experience no intermolecular forces Not attracted to or repelled by the walls of their container Follow the gas laws under all temperatures and pressures

Extreme temperature and pressure Gases deviate most from ideal behavior at high pressures and low temperatures Polarity and size of particles Also affect how a gas behaves

Gas Stoichiometry When gases react, the coefficients in the balanced chemical equation represents both molar amounts and relative volumes 2H2(g) + 2O2(g)  2H2O(g)

Volume – Volume problems What volume of oxygen gas is needed for the complete combustion of 4.00 L of methane gas? CH4(g) + 2O2(g)  CO2(g) + 2H2O(g)

What volume of carbon dioxide gas can be made from 2.36 L of methane?

Volume – Mass problems If 5.00 L of nitrogen reacts completely with hydrogen at a pressure of 3.00 atm and a temperature of 298 K, how much ammonia, in grams, is produced? N2(g) + 3H2(g)  2NH3(g)

NH4NO3(s)  N2O(g) + 2H2O(g) What mass of solid ammonium nitrate must be used to obtain 0.100 L of dinitrogen oxide gas at STP?