Chapter 12 Review
Stoichiometry
Important Vocabulary
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Stoichiometry- The calculations of quantities in chemical reactions in a subject of
chemistry
Mole ratio- a conversion factor derived from the coefficients of a balanced
chemical equation interpreted in terms of moles
Limiting reagent- The reactant that determines the amount of product that can be
formed by a reaction
Excess reagent- The reaction that is not completely used up in a reaction
Theoretical yield- Maximum amount of product that can be formed from given
amounts of reactants
Actual yield- the amount of product that actually forms when the reaction is
carried out in a laboratory
Percent yield- the ration of the actual yield to the theoretical yield in percentage
form
Important information
Six steps on how to do stoichiometry
1.
2.
3.
4.
5.
6.
Balance the equation
Convert to mole
Find the ratios
Find the limiting reagent
Evaluate ratios to find the limiting reagent
Convert back to mass
When converting to liters, you multiply by 22.4, but while converting to grams, you
multiply by the molar mass
Important Equations
1. Mole conversion=
2. Percent Yield=
Review Problems
Multiple Choice
!"## !" !"#$%&
!"#$% !"##
!"#$%& !"#$%
!"#$%#&'()* !"#$%
1) To balance a chemical equation, it may be necessary to adjust the
A. Coefficients.
B. Formulas of the products.
C. Subscripts.
D. Number of products.
2) Which coefficients correctly balance the formula !!! !!! → !! + !! !
A. 1,2,2
B. 1,1,2
C 2,1,1
D. 2,2,2
3) The units of molar mass are
a. g/mol.
b. mol/g.
c. mol/mol.
d. mm/g.
4) In every chemical equation ________
a. Water is formed
b. The mass stays the same
c. The moles stay the same
d. Nothing happens
5) The first step in most stoichiometry problems is to ____
a. Add the coefficients of the reagents
b. Convert given quantities to volumes
c. Convert given quantities to moles
d. Convert given quantities to masses
Short Answer
1) How many grams of !!! !! are produced?
25g Al
86g !!
!" + !! → !!! !! 2) What is the percent yield of NaOH when the theoretical yield is 20.4g and the actual
yield is 17.8g
3) 650 g of nitrogen react with 805g of nitrogen to form ammonia. How many liters of
ammonia are produced?
!! + 3!! → 2!!!
4) Oxygen gas can be produced by decomposing potassium chlorate using the
reaction below. If 138.6 g of KClO3 is heated and decomposes completely, what
mass of oxygen gas is produced?
KClO3 (s) --> KCl (s) + O2 (g)
5) How many grams of aluminum sulfate are produced if 23.33 g Al reacts with
74.44 g CuSO4?
Al (s) + CuSO4 (aq) --> Al2(SO4)3 (aq) + Cu (s)
Answers
1. A
2. B
3. A
4. B
5. C
6. 47.9
7. 87.25
8. 5500
9. 54.286g
10. 53.23g