Exercises 113Exercises
Chemical Equations
00 1.What is a chemical equation? What information does it
contain?
00 2.When balancing chemical equations, you make certain that
the same number of atoms of each element are on both
sides of the equation. What scientific (natural) law requires
that there be equal numbers of atoms of each element in
both the products and the reactants?
00 3.Use words to state explicitly the relationships among num-
bers of molecules of reactants and products in the equa-
tion for the combustion of hexane, C 6 H 14.2C 6 H 14 19O 2 88n12CO 2 14H 2 OBalance each “equation” in Exercises 4–7 by inspection.
00 4.(a) AlCl 2 88nAl 2 Cl 6
(b) N 2 H 2 88nNH 3
(c) KKNO 3 88nK 2 ON 2
(d) H 2 OKO 2 88nKOHO 2
(e) H 2 SO 4 NH 3 88n(NH 4 ) 2 SO 4
00 5.(a) P 4 O 2 88nP 4 O 6
(b) P 4 O 2 88nP 4 O 10
(c) K 2 CO 3 Al 2 Cl 6 88nAl 2 (CO 3 ) 3 KCl
(d) KClO 3 C 12 H 22 O 11 88nKClCO 2 H 2 O
(e) KOHH 3 PO 4 88nKH 2 PO 4 H 2 O
00 6.(a) Fe 2 O 3 CO88nFeCO 2
(b) Mg 3 N 2 H 2 O88nNH 3 Mg(OH) 2
(c) Ca 3 (PO 4 ) 2 H 2 SO 4 88n
Ca(H 2 PO 4 ) 2 Ca(HSO 4 ) 2
(d) (NH 4 ) 2 Cr 2 O 7 88nN 2 H 2 OCr 2 O 3
(e) AlCr 2 O 3 88nAl 2 O 3 Cr
00 7.(a) UO 2 HF88nUF 4 H 2 O
(b) NaClH 2 OSiO 2 88nHClNa 2 SiO 3
(c) Ca(HCO 3 ) 2 Na 2 CO 3 88nCaCO 3 NaHCO 3
(d) NH 3 O 2 88nNOH 2 O
(e) PCl 3 O 2 88nPOCl 3
Calculations Based on Chemical Equations
In Exercises 8–11, (a) write the balanced chemical equation that
represents the reaction described by words, and then perform cal-
culations to answer parts (b) and (c).
00 8.(a) Nitrogen, N 2 , combines with hydrogen, H 2 , to form
ammonia, NH 3.
(b) How many hydrogen molecules are required to react
with 600 nitrogen molecules?
(c) How many ammonia molecules are formed in part (b)?
00 9.(a) Sulfur, S 8 , combines with oxygen at elevated temper-
atures to form sulfur dioxide.
(b) If 250 oxygen molecules are used up in this reaction,
how many sulfur molecules react?
(c) How many sulfur dioxide molecules are formed in
part (b)?
0 10.(a) Lime, CaO, dissolves in muriatic acid, HCl, to form
calcium chloride, CaCl 2 , and water.
(b) How many moles of HCl are required to dissolve 6.7
mol of CaO?
(c) How many moles of water are formed in part (b)?
0 11.(a) Aluminum building materials have a hard, transpar-
ent, protective coating of aluminum oxide, Al 2 O 3 ,
formed by reaction with oxygen in the air. The sulfu-
ric acid, H 2 SO 4 , in acid rain dissolves this protective
coating and forms aluminum sulfate, Al 2 (SO 4 ) 3 , and
water.
(b) How many moles of H 2 SO 4 are required to react with
6.8 mol of Al 2 O 3?
(c) How many moles of Al 2 (SO 4 ) 3 are formed in part (b)?
0 12.Calculate the number of grams of baking soda, NaHCO 3 ,
that contain 14.0 moles of carbon.
0 13.Limestone, coral, and seashells are composed primarily of
calcium carbonate. The test for the identification of a car-
bonate is to use a few drops of hydrochloric acid. The un-
balanced equation isCaCO 3 HCl88nCaCl 2 CO 2 H 2 OProducts Substances produced in a chemical reaction.
Reactants Substances consumed in a chemical reaction.
Reaction ratio The relative amounts of reactants and products
involved in a reaction; may be the ratio of moles, or masses.
Reaction stoichiometry Description of the quantitative rela-
tionships among substances as they participate in chemical re-
actions.
Sequential reaction A chemical process in which several reaction
steps are required to convert starting materials into products.
Solute The dispersed (dissolved) phase of a solution.
Solution A homogeneous mixture of two or more substances.
Solvent The dispersing medium of a solution.
Stoichiometry Description of the quantitative relationships
among elements and compounds as they undergo chemical
changes.
Theoretical yield The maximum amount of a specified product
that could be obtained from specified amounts of reactants, as-
suming complete consumption of the limiting reactant accord-
ing to only one reaction and complete recovery of the product.
Compare with Actual yield.