AP Chemistry
Mr. Marquez
First Semester Review
Chapter 3: Stoichiometry
1. The molecular formula of aspartame is C14H18N2O5
◦
Calculate the molar mass of aspartame.
◦
What amount (moles) of molecules are
present in 10.0 g aspartame?
◦
Calculate the mass in grams of 1.56 mol
aspartame.
◦
What number of molecules are in 5.0 mg
aspartame?
◦
What number of atoms of nitrogen are in
1.2 g aspartame?
◦
What is the mass in grams of 1.0x109
molecules of aspartame?
◦
What is the mass in grams of one molecule
of aspartame?
2. A white powder is analyzed and found to contain
43.64% P and 56.36% O by mass. The compound has a
molar mass of 283.88 g/mol. What are the
compound’s empirical and molecular formulas?
3. Suppose a substance has been prepared that is
composed of C, H, and N. When 0.1156 g of
compound is reacted with oxygen, 0.1638g of CO2 and
0.1676 g H2O are collected. What is the empirical
formula of the compound?
4. Solid lithium hydroxide is used in space vehicles to
remove exhaled carbon dioxide form the living
environment by forming solid lithium carbonate and
liquid water. What mass of gaseous carbon dioxide can
be absorbed by 1.00 kg of lithium hydroxide?
5. Nitrogen gas can prepared by passing gaseous ammonia
over solid copper(II) oxide at high temperatures. The
other products of the reaction are solid copper and
water vapor. If a sample containing 18.1 g of NH3 is
reacted with 90.4 g of CuO, which is the limiting
reactant? How many grams of N2 will be formed?
6. Methanol (CH3OH), also called methyl alcohol, is the
simplest alcohol. It is used as a fuel in race cars and is
potential replacement for gasoline. Methanol can be
manufactured by combination of gaseous carbon
monoxide and hydrogen. Suppose 68.5 kg CO(g) is
reacted with 8.60 kg H2(g). Calculate the theoretical
yield of methanol. If 3.57x104 g CH3OH is actually
produced, what is the percent yield of methanol?
7. A 0.755 g sample of hydrated copper (II) sulfate
CuSO4*xH2O
Was heated carefully until it had changed completely to
anhydrous copper (II) sulfate (CuSO4) with a mass of 0.483
g. Determine the value of x. (essentially the formula of the
hydrate)
AP Chemistry
Chapter 4: Reactions and Solution Stoichiometry.
Mr. Marquez
Precipitation Reactions
Precipitation reactions involve aqueous solutions and a precipitate (s, l, or g) is formed. It is important
for you to note the following:
 Strong acids and strong bases completely ionize (H2SO4 only ionizes one H: H+ + HSO4-)
 HCl, HBr, HNO3, HI, HClO4, HIO4, H2SO4, HClO3
 Weak acid and weak bases keep their molecular form.
 Any acid not listed above is weak, a weak base is NH3 and water.
 Some products for decomposes to form gases (H2CO3, H2SO3, HNO2, NH4OH)
 To determine products, think of new pairs. Look at ions that are formed
ALWAYS, write your final equation as a net ionic equation!
1. For the following problems, determine the overall balance reaction and the net ionic equation.
a. Aqueous solutions of sulfuric acid and excess barium hydroxide are combined.
b. Aqueous hydrochloric acid reacts with solid iron (II) sulfide.
c. Excess aqueous acetic acid reacts with aqueous sodium sulfite.
d. Solid calcium carbonate in aqueous suspension reacts with dilute hydrochloric acid.
2. Precipitation Reactions: Predict the following precipitation reaction, and then write the net
ionic equation.
a. The reaction of aqueous lead (II) nitrate and aqueous potassium hydroxide.
b. The reaction of aqueous ammonium sulfide and aqueous mercury (II) nitrate.
c. The reaction of nickel (II) chloride is mixed with an aqueous potassium hydroxide.
3. Acid-Base Reactions: Predict the following Acid-Base Reaction, and then write the net ionic
equation.
a. H3PO4(aq) + KOH(aq) →
b. HClO4(aq) + NH3(aq) →
4. Oxidation-Reduction Reactions: Balance the following net ionic equations
a. CH2O(aq) + Ag+(aq) → HCO2H(aq) + Ag(s)
(acidic solution)
b. N2H4(aq) + Ag2O(s) → N2(g) + Ag(s)
(basic solution)
5. Gas Forming Reactions: Predict the following reaction and write the net ionic equations
a.
b.
c.
d.
Aqueous sodium bicarbonate is mixed with aqueous acetic acid.
An aqueous solution of ammonium chloride and sodium hydroxide
A solution of lithium sulfite and nitric acid
Solid iron (II) carbonate reacts with nitric acid.
AP Chemistry
6. An 20.0 ml of 0.250 M iron (II) chloride is mixed
with 30.0 mL of 0.450 M ammonium sulfide.
a. Predict the products of the reaction and
then balance the completed equation.
b. Determine the net ionic equation.
c. Identify the limiting reagent and excess
reagent.
d. How many grams of precipitate where
produced?
e. Determine the moles of ion in excess.
f. What are the concentrations of the ions
remaining after the precipitation reaction
is completed.
7. Suppose you mix 25.0 mL of 0.234 M FeCl3 solution
with 42.5 mL of 0.453 M NaOH.
a. What is the maximum mass, in grams, of
Fe(OH)3 that will precipitate?
b. Which reactant is in excess?
c. What is the concentration of the excess
reactant remaining in solution after the
maximum mass of Fe(OH)3 has
precipitated?
8. A noncarbonated soft drink contains an unknown
amount of citric acid, H3C6H5O7. If 100. mL of the
soft drink requires 33.51 mL of 0.0102 M NaOH to
neutralize the citric acid completely what mass of
citric acid does the soft drink contain per 100. mL?
The reaction of citric acid and NaOH is………..
H3C6H5O7(aq) + 3NaOH(aq)→ Na3C6H5O7(aq) + 3H2O(l)
9. What volume of 0.500 M HCl solution is needed to
neturalize each of the following:
a. 10.0 mL of a 0.300 M NaOH solution
b. 10.0 mL of 0.200 M Ba(OH)2
10. Typical blood serum is about 0.14 M NaCl. What
volume of blood contains 1.0 mg NaCl?
11. What volume of 0.109 M HNO3, in milliliters, is
required to react completely with 2.50 g Ba(OH)2?
Mr. Marquez
12. You place 2.56 g of CaCO3 in a beaker containing
250. mL of 0.125 MHCl. When the reaction has
ceased, does any calcium carbonate remain? What
mass of CaCl2 can be produced
CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l)
13. A sample of 0.6760 g of an unknown compound
containing barium ions (Ba+2) is dissolved in water
and treated with excess Na2SO4. If the mass of the
BaSO4 precipitate formed is 0.4105 g, what is the
percent by mass of Ba in the original unknown
compound?
14. Potassium dichromate (K2Cr2O7) is a bright orange
compound that can be reduced to a blue-violet
solution of Cr3+ ions. Under certain conditions,
K2Cr2O7 reacts with ethyl alcohol (C2H5OH) as
follows:
a. Balance this equation using the half
reaction method under acidic and basic
conditions.
15. An environment chemist analyzed the effluent
from an industrial process known to produce the
compounds carbon tetrachloride and benzoic acid
(HC7H5O2), a weak acid that has one acidic
hydrogen atom per molecule. A sample of this
effluent weighing 0.3518 g was shaken with water,
and the resulting aqueous solution required 10.59
mL of 0.1546 M NaOH for neutralization. Calculate
the mass percent of HC7H5O2 in the original
sample.
16. How many grams of silver chloride can be
prepared by the reaction of 100.0 mL of 0.20 M
silver nitrate with 100.0 mL of 0.15 M calcium
chloride? Calculate the concentrations of each ion
remaining in solution after precipitation is
complete.
17. When aqueous solutions fo Na2SO4 and Pb(NO3)2
are mixed, PbSO4 precipitates. Calculate the mass
of PbSO4 formed when 1.25 L of 0.0500 M
Pb(NO3)2 and 2.00 L of 0.0250 M Na2SO4 are mixed.
AP Chemistry
Mr. Marquez