Name ___________________
Period _____ Date _________
Chapter 8 and 9 Study Guide
1. Define the following terms
a. Percent composition (sometimes called mass percent)
b. Empirical Formula
c. Molecular Formula
d. Mole Ratio
e. Stoichiometry
f. Limiting Reactant
g. Theoretical Yield
h. Percent Yield
i. Actual Yield
j. Molar Mass
2. Calculate the percent composition of the element listed first in the formulas for
each of the following compounds.
a. H2SO4
b. Ca(OH)2
c. HC2H3O2
d. CO2
e. N2O
f. NaOCl
3. Give the empirical formula that corresponds to each of the following molecular
formulas.
a. Na2O2
b. C8H6O4
c. C12H12N2O3
d. C4H6Cl2
4. A compound was analyzed and was found to contain the following percentages of
the elements by mass: 89.56% barium; 10.44% oxygen. Determine the empirical
formula.
5. A compound used in the nuclear industry contains uranium and fluorine. The
compound is made up of 67.61% uranium.
a. What is percent composition of fluorine?
b. What is the empirical formula of the compound?
6. During excessive physical activity, lactic acid (molar mass = 90.08 g/mol) forms
in muscle tissue and is responsible for muscle soreness. Elemental analysis shows
that this compound contains 40% C, 6.71% H, and 53.3% O.
a. Determine the empirical formula of lactic acid.
b. Determine the molecular formula.
7. Consider the balanced chemical equation
4Al(s) + 3O2 (g) ® 2Al 2O3 (s)
a. What mole ratio would you use to calculate how many moles of oxygen
gas would be needed to react completely with a given number of moles of
aluminum metal?
b. What mole ratio would you use to calculate the number of moles of
product that would be expected if a given number of moles of aluminum
metal reacts completely?
8. For each of the following balanced chemical equations, calculate how many
moles of product(s) would be produced if 0.500 mole of the first reactant were to
react completely.
a. 3H 2SO4 (aq) + 2Fe(s) ® Fe2 SO4 (aq) + 3H 2 (g)
(
)
3
b. SiCl 4 (l) + 2H2O(l) ® SiO2 (s) + 4HCl(g)
9. For each of the following unbalanced equations calculate how many grams of
each product would be produced by complete reaction of 12.5 g of the reactant
indicated in boldface. Indicate clearly the mole ratio used for the conversion.
a. TiBr4 (g) + H2 (g) ® Ti(s) + HBr(g)
b. SiH4 (g) + NH3 (g) ® Si3 N4 (s) + H 2 (g)
c. Cu2S(s) ® Cu(s) +S(g)
10. Lead (II) Carbonate, also called “white lead,” was formerly used as a pigment in
white paints. However, because of tis toxicity, lead can no longer be used in
paints intended for residential homes. Lead (II) carbonate is prepared industrially
by reaction of aqueous lead (II) acetate with carbon dioxide gas. The unbalanced
equation is
Pb C2 H3O2 (aq) + H 2O(l) + CO2 (g) ® PbCO3 (s) + HC2 H3O2 (aq)
(
)
2
Suppose an aqueous solution containing 1.25 g of lead (II) acetate is treated with
5.95 g of carbon dioxide. Calculate the theoretical yield of lead (II) carbonate.
11. According to his prelab theoretical yield calculations, a student’s experiment
should have produced 1.44 g of magnesium oxide. When he weighed his product
after reaction, only 1.23 g of magnesium oxide was present. What was his percent
yield?