Date ________________
Chapter 11 Gases
Section 1 Gases and Pressure
What are the 4 measurable quantities that are needed to fully describe a gas?
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Why does the volume of a balloon increase in size when you blow air into it?
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What is pressure? Write the equation:
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What is the SI unit for pressure?
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The atmosphere (the shell surrounding the Earth) exerts a pressure. The pressure is caused by the weight of the gases that compose the atmosphere, 78% nitrogen, 21% oxygen, and 1% other gases. Atmospheric pressure is the sum of the individual pressures of the various gases in the atmosphere.
What is a barometer?
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Evangelista Torricelli developed the first barometer.
How it works:
The mercury will only fall until the pressure exerted by its weight is equal to the pressure exerted by the atmosphere.
A __________ measures the pressure of an enclosed gas sample.
How it works:
The difference in the height of mercury in the two arms of the U-tube is a measure of the gas pressure in the container.
What are the standard units for temperature and pressure?
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The pressure of each gas in a mixture is called the __________ _____________ of that gas.
The pressure exerted by each gas in a mixture is independent of that exerted by other gases present.
Dalton's law of partial pressures: the total pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases.
Gases Collected by Water Displacement
The gas produced by a reaction in the flask displaces the water in the collection bottle.
A gas collected by water displacement is always mixed with water vapor. The total pressure of the mixture is equal to the atmospheric pressure in the laboratory. Use Dalton's Law of Partial Pressures to determine the pressure of the collected gas.
Section 11-2
The Gas Laws
The gas laws are simple math relationships between the volume, temperature, pressure, and quantity of a gas.
1. Boyle's Law: Pressure-Volume Relationship
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P1 and V1 represent the _________ ____________ _____ _____________; P2 and V2 represent the ______ ______ ____ ______________.
2. Charles's Law: Volume-Temperature Relationship
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V1 and T1 represent the _________ ____________ ______ ________________ and V2 and T2 represent the ______ ______ _____ ________________
3. Gay-Lussac's Law: Pressure-Temperature Relationship
as one increases the other increases
directly proportional to each other using Kelvin temperature
used to compare changing values of temperature and pressure
P1 and T1 represent the __________ ____________ _____ ______________ and P2 and T2 represent the ______ ______ ____ _____________
4. Combined Gas Law: relationship between pressure, volume, and temperature of a fixed amount of gas
Section 11-3
Gas Volumes and the Ideal Gas Law
Volume-Mass Relationships of Gases
§ Gay-Lussac's law of combining volumes of gases: at constant temperature and pressure, the volumes of gaseous reactants and products can be expressed as ratios of small whole numbers.
§ Avogadro's law: equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.
§ Example: Balloons filled with hydrogen, oxygen, and carbon dioxide all contain the same number of molecules at the same temperature and pressure.
Molar Volume of Gases:
§ one mole contains 6.022 x 10 molecules
§ one mole of any gas will occupy the same volume as one mole of any other gas at the same temperature and pressure (mass does not matter)
§ standard molar volume of a gas: 22.4 L; this is the volume occupied by one mole of a gas at STP
§ 1 mol = 22.4 L is a conversion factor
Gas Stoichiometry
For gaseous reactants or products, the coefficients in chemical equations not only indicate molar amounts and mole ratios but also reveal volume ratios.
Ideal Gas Law:
§ the mathematical relationship among _____________________________________________________________________________________________________________.
§ as the number of molecules of a gas _____________, the pressure _____________.
§ Equation:
§ R is the _________ _______ _____________
the constant is different depending on the units used
we’ll use
What is the pressure in atmospheres exerted by a 0.500 mol sample of nitrogen gas in a 10.0 L container at 298 K?
What pressure, in atmospheres, is exerted by 0.325 mol of hydrogen gas in a 4.08 L container at 35°C?
A gas sample occupies 8.77 L at 20°C.What is the pressure, in atmospheres, given that there are 1.45 mol of gas in the sample?
What is the volume, in liters, of 0.250 mol of oxygen gas at 20.0°C and 0.974 atm pressure?
A sample that contains 4.38 mol of a gas at 250 K has a pressure of 0.857 atm. What is the volume?
How many liters are occupied by 0.909 mol of nitrogen at 125°C and 0.901 atm pressure?
What mass of chlorine gas, Cl2, in grams, is contained in a 10.0 L tank at 27°C and 3.50 atm of pressure?
How many grams of carbon dioxide gas are there in a 45.1 L container at 34°C and 1.04 atm?
What is the mass, in grams, of oxygen gas in a 12.5 L container at 45°C and 7.22 atm?
A sample of carbon dioxide with a mass of 0.30 g was placed in a 250 mL container at 400. K. What is the pressure exerted by the gas?
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