Transcript Chemistry 12.2

Chemistry 12.2
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12.2
Chemical Calculations
The effectiveness of car’s air bags
is based on the rapid conversion of
a small mass of sodium azide into a
large volume of gas. The entire
reaction occurs in less than a
second. You will learn how to use a
balanced chemical equation to
calculate the amount of product
formed in a chemical reaction.
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12.2
Chemical Calculations
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Writing and Using Mole Ratios
Writing and Using Mole Ratios
How are mole ratios used in chemical
calculations?
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12.2
Chemical Calculations
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Writing and Using Mole Ratios
In chemical calculations, mole ratios are
used to convert between moles of
reactant and moles of product, between
moles of reactants, or between moles of
products.
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12.2
Chemical Calculations
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Writing and Using Mole Ratios
Mole-Mole Calculations
A mole ratio is a conversion factor derived from
the coefficients of a balanced chemical equation
interpreted in terms of moles.
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12.2
Chemical Calculations
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Writing and Using Mole Ratios
To determine the number of moles in a sample
of a compound, first measure the mass of the
sample. Then use the molar mass to calculate
the number of moles in that mass.
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SAMPLE PROBLEM 12.2
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SAMPLE PROBLEM 12.2
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SAMPLE PROBLEM 12.2
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SAMPLE PROBLEM 12.2
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Practice Problems for Sample Problem 12.2
Problem Solving 12.12 Solve
Problem 12 with the help of an
interactive guided tutorial.
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12.2
Chemical Calculations
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Writing and Using Mole Ratios
Mass-Mass Calculations
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SAMPLE PROBLEM 12.3
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SAMPLE PROBLEM 12.3
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SAMPLE PROBLEM 12.3
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SAMPLE PROBLEM 12.3
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Practice Problems for Sample Problem 12.3
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Problem Solving 12.13 Solve
Problem 13 with the help of an
interactive guided tutorial.
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12.2
Chemical Calculations
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Other Stoichiometric Calculations
Other Stoichiometric Calculations
What is the general procedure for
solving a stoichiometric problem?
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12.2
Chemical Calculations
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Other Stoichiometric Calculations
In a typical stoichiometric problem, the
given quantity is first converted to
moles. Then the mole ratio from the
balanced equation is used to calculate
the number of moles of the wanted
substance. Finally, the moles are
converted to any other unit of
measurement related to the unit mole, as
the problem requires.
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12.2
Chemical Calculations
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Other Stoichiometric Calculations
Solution Diagram
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12.2
Chemical Calculations
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Other Stoichiometric Calculations
Problem-Solving Approach
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Chemical Calculations
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Other Stoichiometric Calculations
Simulation 13
Strengthen your analytical skills by solving
stoichiometric problems.
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SAMPLE PROBLEM 12.4
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SAMPLE PROBLEM 12.4
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SAMPLE PROBLEM 12.4
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SAMPLE PROBLEM 12.4
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Practice Problems for Sample Problem 12.4
Problem Solving 12.15 Solve
Problem 15 with the help of an
interactive guided tutorial.
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12.2 Section Quiz.
Assess students’ understanding
of the concepts in Section 12.2.
Continue to:
-or-
Launch:
Section Quiz
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12.2 Section Quiz.
1. How many moles of water are produced when 2.5
mol of O2 react according to the following equation?
C3H8 + 5O2  3CO2 + 4H2O
a. 2.0
b. 2.5
c. 3.0
d. 4.0
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12.2 Section Quiz
2. Nitrogen gas reacts with hydrogen gas to produce
ammonia gas. N2(g) + 3H2(g)  2NH3(g) What
volume of H2 is required to react with 3.00 L of N2,
and what volume of NH3 is produced at 200°C?
a. volume of H2 = 9.00 L, volume of NH3 = 6.00 L
b. volume of H2 = 3.00 L, volume of NH3 = 3.00 L
c. volume of H2 = 3.00 L, volume of NH3 = 6.00 L
d. volume of H2 = 1.00 L, volume of NH3 = 1.50 L
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12.2 Section Quiz
3. Automotive airbags inflate when sodium azide, NaN3,
rapidly decomposes to its component elements via
this reaction: 2NaN3  2Na + 3N2. How many grams
of sodium azide are required to form 5.00 g of
nitrogen gas?
a. 11.61 g
b. 17.41 g
c. 7.74 g
d. 1.36 g
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