© 2013 Pearson Education, Inc. Chapter 7, Section 8 General, Organic, and Biological Chemistry...
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Transcript of © 2013 Pearson Education, Inc. Chapter 7, Section 8 General, Organic, and Biological Chemistry...
© 2013 Pearson Education, Inc. Chapter 7, Section 8
General, Organic, and Biological Chemistry
Fourth EditionKaren Timberlake
7.8The Ideal Gas Law
Chapter 7Gases
© 2013 Pearson Education, Inc.Lectures
© 2013 Pearson Education, Inc. Chapter 7, Section 8
The four properties used in the measurement of a gas, pressure (P), volume (V), temperature (T), and amount (n),
can be combined to give a single expression called theideal gas law. PV = nRT
Ideal Gas Law
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Rearranging the ideal gas law equation shows that thefour gas properties equal a constant, R.
To calculate the value of R, we substitute the STPconditions for molar volume into the expression:
R, Ideal Gas Constant
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Another value for the universal gas constant, R, is obtained using mmHg for the STP pressure. What is the value of R when a pressure of 760 mmHg rather than 1.00 atm is used?
Learning Check
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Another value for the universal gas constant, R, isobtained using mmHg for the STP pressure. Whatis the value of R when a pressure of 760 mmHgrather than 1.00 atm is used?
Solution
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Unit Summary for R, the Ideal Gas Constant
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Guide to Using the Ideal Gas Law
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Dinitrogen oxide (N2O), laughing gas, is used by dentists as an anesthetic. If a 20.0 L tank of laughing gas contains 2.86 moles of N2O at 23 C, what is the pressure (mmHg) in the tank?
Learning Check
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
If a 20.0 L tank of laughing gas contains 2.86 moles ofN2O at 23 ˚C, what is the pressure (mmHg) in the tank?
Step 1 State the given and needed quantities. Analyze the Problem.
Solution
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
If a 20.0 L tank of laughing gas contains 2.86 moles ofN2O at 23 ˚C, what is the pressure (mmHg) in the tank?
Step 2 Rearrange the ideal gas law equation to solve for the needed quantity.
Solution
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
If a 20.0 L tank of laughing gas contains 2.86 moles ofN2O at 23 ˚C, what is the pressure (mmHg) in the tank?
Step 3 Substitute the gas data into the equation and calculate the needed quantity.
Solution
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Ideal Gas Law and Molar Mass
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Learning Check
A cylinder contains 5.0 L of an unknown gas at 20.0 ˚C and 0.85 atm. If the mass of the gas in the cylinder is 5.8 g, what is the molar mass of the gas?
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
A cylinder contains 5.0 L of an unknown gas at 20.0 ˚Cand 0.85 atm. If the mass of the gas in the cylinder is5.8 g, what is the molar mass of the gas?
Step 1 State the given and needed quantities. Analyze the Problem
Solution
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
A cylinder contains 5.0 L of an unknown gas at 20.0 ˚Cand 0.85 atm. If the mass of the gas in the cylinder is5.8 g, what is the molar mass of the gas?Step 2 Rearrange the ideal gas law equation to solve for the number of moles.
Step 3 Obtain the molar mass by dividing the given number of grams by the number of moles.
Solution
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Chemical Reactions and the Ideal Gas Law
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Learning Check
Nitrogen gas reacts with hydrogen gas to produce ammonia (NH3) gas. How many liters of NH3 can be produced at 0.93 atm and 24 ˚C from a 16.0-g sample of nitrogen gas and an excess of hydrogen gas?
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Solution
How many liters of NH3 can be produced at 0.93 atm and24 ˚C from a 16.0-g sample of nitrogen gas and anexcess of hydrogen gas?
Step 1 State the given and needed quantities.
Analyze the Problem.
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Solution
How many liters of NH3 can be produced at 0.93 atm and24 ˚C from a 16.0-g sample of nitrogen gas and anexcess of hydrogen gas?
Step 2 Write a plan to convert the given quantity to the needed moles.
grams molar moles mole−mole moles of N2 mass of N2 factor of NH3
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
How many liters of NH3 can be produced at 0.93 atm and24 ˚C from a 16.0-g sample of nitrogen gas and anexcess of hydrogen gas?
Step 3 Write the equalities for molar mass and mole– mole factors.
Solution
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Solution
How many liters of NH3 can be produced at 0.93 atm and24 ˚C from a 16.0-g sample of nitrogen gas and anexcess of hydrogen gas?
Step 4 Set up the problem to calculate moles of needed quantity.
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© 2013 Pearson Education, Inc. Chapter 7, Section 8
Solution
How many liters of NH3 can be produced at 0.93 atm and24 ˚C from a 16.0-g sample of nitrogen gas and anexcess of hydrogen gas?
Step 5 Convert the moles of needed to volume using
the ideal gas law equation.
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