College Prep Chemistry Final Examination Review
Answer the following questions. The information will be important for answering matching and multiple
choice questions on the final exam.
1.) What is the difference between an acid and a base?
An acid is a substance which dissociates in water to produce hydrogen ions. An acidic substance
generally makes the pH level of solutions decrease. A base is a substance which dissociates in
water to produce hydroxide ions or combines with hydrogen ions to remove them from a
solution. A basic substance generally makes the pH level of solutions increase.
2.) What is the difference between an anion and a cation?
An anion is a negatively charged ion. A cation is a positively charged ion.
3.) What is the difference between a covalent bond and an ionic bond?
In a covalent bond, two atoms share one or more electrons in their valence energy levels. In an
ionic bond, one atom transfers one or more electrons from its valence energy level to another
atom’s valence energy level.
4.) What is the difference between a molecule and an ionic lattice? Which is easier to dissociate?
A molecule results when two or more atoms share covalent bonds. An ionic lattice results from
the electrical attraction of anions and cations which arranges them into a three dimensional
structure. Since the ionic lattice is merely held together by attractions rather than shared
electrons, it is easier to dissociate.
5.) What does it mean to say that a substance is soluble?
A substance is soluble if it dissolves into another substance, usually water.
6.) Define electronegativity? How can this be used to predict the type of chemical bond that will
form between two atoms?
Electronegativity is a numerical rating of an atom’s ability to attract to itself the shared electrons
in a covalent bond. Atoms with the same or very similar electronegativity tend to form nonpolar
covalent bonds. Atoms with electronegativity differences greater than 0 but less than 1.9 tend to
form polar covalent bonds. Atoms with electronegativity differences greater than 1.9 tend to
form ionic bonds.
7.) What is Avogadro’s number? Why is this number significant?
Avogadro’s number is 6.022 x 1023. It represents the number of atoms or molecules in a mole of
any substance.
8.) What is a precipitate?
A precipitate is a solid insoluble substance that results when two aqueous solutions are combined.
9.) List the seven atoms that form diatomic molecules in nature. (Use the mnemonic device to
help you.)
The seven atoms that form diatomic molecules in nature are Br, I, N, Cl, H, O, and F. The
mnemonic device to remember them combines these chemical symbols into a word that sounds
like “brinkelhoff.”
10.) What is a resonance form of a compound? Draw all three possible resonance forms for
CO2?
Resonance forms of Lewis dot diagrams occur when there are more than one valid way to
arrange the electrons of single compound. The resonance forms of carbon dioxide are draw
below. Scientists generally accept that the actual structure of the molecule is a mixture of all
valid resonance forms.
11.) In a chemical equation, which are the reactants and which are the products?
In a chemical equation, reactants are written to the left of the reaction arrow. Products are written
to the right of the reaction arrow.
12.) What do the subscripts s, l, g, and aq mean when used in a chemical equation?
These subscripts indicate the state in which the reactant or product exists. The s represents a
solid substance. The l represents a liquid substance. The g represents a gaseous substance. The
aq represents an aqueous solution, a substance dissolved in water.
13.) Draw a Lewis dot diagram for phosphorus, (chemical symbol: P). Circle the lone pair of
electrons in this dot diagram.
14.) What happens to the energy of the individual atoms when a chemical bond forms between
them?
When chemical bonds form energy is always released.
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15.) Predict the chemical formula of the compound that results from the combination of the two
elements given.
First element
Second element
Chemical formula
Na
Br
NaBr
Mg
Cl
MgCl2
N
H
NH3
K
O
K2O
Ba
S
BaS
16.) Review section 5.6 in your textbook. Use the information in this section about the
electronegativity of atoms to complete the chart.
Chemical
formula
Electronegativity
of first element
Electronegativity
of second
element
Type of chemical bond between
atoms
NaF
0.9
4.0
Ionic bond
O2
3.5
3.5
Covalent bond
CH4
2.5
2.1
Nonpolar covalent bond
PCl4
2.1
3.0
Polar covalent bond
CsCl
0.7
3.0
Ionic bond
HI
2.1
2.5
Polar covalent bond
17.) Name the following compounds using proper nomenclature conventions:
a. KI
Potassium iodide
b. MgCl2
Magnesium chloride
c. CuO
Copper (II) oxide
d. CuO2
Copper (IV) oxide
e. TiO2
Titanium (IV) oxide
f. Au2S3
Gold (III) sulfide
g. Mn2O7
Manganese (VII) oxide
h. Fe(OH)3
Iron (III) hydroxide
i. CaCO3
Calcium carbonate
j. Na2SO4
Sodium sulfate
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k. NH4OH
Ammonium hydroxide
l. Ba(C2H3O2)2 Barium acetate
m. P4S7
Tetraphosphorus heptasulfide
n. SF6
Sulfur hexafluoride
o. B4H10
Tetraboron decahydride
p. XeO4
Xenon tetroxide
q. HBr
Hydrobromic acid
r. H2SO3
Sulfurous acid
s. HNO3
Nitric acid
18.) When naming acids, when do you use the prefix hydro- or the suffixes –ous or –ic?
The prefix hydro- is used when naming a binary acid containing hydrogen and one other
element. The suffixes –ous and –ic are used for oxyacids that are formed by hydrogen and a
polyatomic ion. If the polyatomic ion ends in –ite, then it is changed to –ous when naming the
acid as in sulfite in example r. above. If the polyatomic ion ends in –ate, then it is change to –ic
when naming the acid as in nitrate in example s. above.
19.) Draw the Lewis dot diagrams for the following atoms and compounds.
a) Se
b) AlCl3
c) CH2O
d) HSO3-
e) C3H6 (this one is a bit harder)
20.) List four signs that a chemical reaction has occurred.
Signs that a chemical reaction has occurred include the evolution of a gas, the formation of a
precipitate, a change in temperatures, a change in color that cannot be explained simply by the
mixing of the substances, or the production of a flame or explosion.
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21.) Predict which of the following chemical reactions would NOT occur? Explain why using the
activity series.
a) 3 PtO2 + 4 Pd → 2 Pd2O3 + 3 Pt
Yes, this reaction would occur. Paladium is higher on the activity series than platinum.
b) 2 AgNO3 + Fe → Fe(NO3)2 + 2 Ag
Yes, this reaction would occur. Iron is higher on the activity series than silver.
c) CoCl3 + Bi → BiCl3 + Co
No, this reaction would not occur. Bismuth is lower on the activity series than cobalt.
d) 3 LiOH + Sb → Sb(OH)3 + 3 Li
No, this reaction would not occur. Antimony is lower on the activity series than lithium.
22.) Balance the following chemical equations. Write the complete ionic equation for each
chemical reaction. Then write the net ionic equation for each chemical reaction. Circle the
spectator ions in the complete ionic equation. Draw a box around the precipitate in the net
ionic equation.
a) Ni(NO3)2 (aq) + 2 NaOH (aq)  Ni(OH)2 (s) + 2 NaNO3 (aq)
CIE: Ni2+ + 2 NO3- + 2 Na+ + 2 OH- → Ni(OH)2 + 2 Na+ + 2 NO3TIE: Ni2+ + 2 OH- → Ni(OH)2
b) NaCl (aq) + AgC2H3O2 (aq)  NaC2H3O2 (aq) + AgCl (s)
CIE: Na+ + Cl- + Ag+ + C2H3O2- → Na+ + C2H3O2- + AgCl
TIE: Ag+ + Cl- → AgCl
c) BaCl2 (aq) + Na2SO4 (aq)  2 NaCl (aq) + BaSO4 (s)
CIE: Ba2+ + 2 Cl- + 2 Na+ + SO42- → 2 Na+ + 2 Cl- + BaSO4
TIE: Ba2+ + SO42- → BaSO4
d) Hg2(NO3)2 (aq) + CaCl2 (aq)  Ca(NO3)2 (aq) + Hg2Cl2 (s)
CIE: Hg22+ + 2 NO3- + Ca2+ + 2 Cl- → Ca2+ + 2 NO3- + Hg2Cl2
TIE: Hg22+ + 2 Cl- → Hg2Cl2
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23.) Complete the chart for each type of chemical reaction.
Model for the Reaction
Type of Chemical Reaction
A + B → AB
Synthesis (Combination)
AB → A + B
Decomposition
AX + B → A + BX
Single Replacement
AX + BY → AY + BX
Double Replacement
HA + BOH → H2O + AB
CxHyOz + O2 → CO2 + H2O
Acid-Base Neutralization
Combustion
“Signposts” that help you
identify the chemical
reaction.
Two or more substances
combines to form a single
substance.
At least one substances splits
into two or more substances.
A substance combined with
another is replaced by a third
substance.
Two substances switch the
substances to which they
were originally bonded.
Water is a product.
Hydrogen and hydroxide that
makes water were originally
bonded with two other
substances which usually
combine to make a new
product.
Water and carbon dioxide
are products. Oxygen is a
reactant.
24.) Calculate the molar mass of the following. (Extra practice: Name each compound. Use the
polyatomic ion chart to help.)
a) CH4
(12.01g x 1) + (1.01g x 4) = 16.05g
Carbon tetrahydride (or methane)
b) Na2SiO3
(22.99g x 2) + (28.09g x 1) + (16.00g x 3) = 122.07g
Sodium silicate
c) Al2S3
(26.98g x 2) + (32.07g x 3) = 150.17g
Aluminum sulfide
d) K2MoO4
(39.10g x 2) + (95.94g x 1) + (16.00g x 4) = 238.14g
Potassium molybdate
e) (NH4)2S2O3
(14.01g x 2) + (1.01g x 8) + (32.07g x 2) + (16.00g x 3) = 148.27g
Ammonium thiosulfate
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In questions 25 through 30 the chemical formulas are purposely omitted. Determine the chemical
formulas first so that you can complete the stoichiometry correctly.
25.) If you have 4.53 moles of hydrogen, then how many molecules of hydrogen do you have?
6.02 x1023 atoms 1 molecule H 2
4.53 mol H x
x
1.36 x 1024 molecules H 2
1 mol H
2 atoms H
26.) What is the mass of 5.99 moles of osmium (II) chloride?
5.99 mol OsCl2 x
261.13 grams OsCl2
1560 grams OsCl2
1 mol OsCl2
Note rounding of answer to accommodate significant figures here.
27.) If you have 350.0 grams of gallium phosphide, then how many moles of this compound do
you have?
350.0 grams GaP x
1 mol GaP
 3.476 mol GaP
100.69 grams GaP
28.) If you have 5.03 x 1024 atoms of berkelium, then how many moles of berkelium do you have?
5.03 x 1024 atoms Bk x
1 mol Bk
 8.36 mol Bk
6.02 x 1023 atoms Bk
29.) What is the mass of 7.88 x 1023 formula units of iron (III) chloride? (Hint: A formula unit is the
equivalent of a molecule for ionic compounds.)
7.88 x 1023 f .u. FeCl3 x
1 mol FeCl3
162.20 grams FeCl3
x
 212 grams FeCl3
23
6.02 x 10 f .u. FeCl3
1 mol FeCl3
30.) How many molecules would you have if you had a 320.07 gram sample of carbon
tetrachloride?
1 mol CCl4
6.02 x 1023 molecules CCl4
320.07 grams CCl4 x
x
1.2527 x 1024 molecules CCl4
153.81 grams CCl4
1 mol CCl4
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31.) What is a limiting reagent? What is an excess reagent? In what type of chemical reaction
would these terms apply?
The limiting reagent limits the progress of the reaction because it is used up (or runs out) before
the other reactants in a chemical reaction. The excess reagent(s) are present in quantities that do
not run out in the progress of the reaction compared to the limiting reagent. These terms apply
to chemical reactions in which the quantities of the reactants are not present in the precise molar
amounts predicted by a chemical equation.
32.) Magnesium metal is reactive enough that it will even burn in an environment of carbon
dioxide instead of oxygen. The balanced equation for the combustion of magnesium in
carbon dioxide is show below.
2 Mg + CO2 → 2 MgO + C
a) What is the theoretical yield of magnesium oxide if a 5.00 gram piece of magnesium
were completely combusted in the reaction?
5.00 grams Mg x
1 mol Mg
2 mol MgO 40.31 grams MgO
x
x
 8.29 grams MgO
24.31 grams Mg 2 mol Mg
1 mol MgO
b.) If after completely combusting the magnesium, you obtained 6.12 grams of magnesium
oxide, then what is the percent yield for this chemical reaction?
6.12 grams MgO
x 100  73.8%
8.29 grams MgO
c.) Another student performs this chemical reaction a different way and finds a percent yield
of 87%. Using this student’s method, how many grams of magnesium oxide can be
produced from 5.00 grams of magnesium and excess CO2?
87
x 8.29 grams MgO  7.21 grams MgO
100
d.) Typically this reaction is conducted using dry ice, solidified carbon dioxide. If the
reaction in part a above were conducted with a 20.00 gram piece of dry ice, how much
dry ice (excess reagent) would be left over after the reaction completed? (Assume that
there is no loss of carbon dioxide from sublimation.)
8.29 grams MgO x
1 mol CO2 44.01 grams CO2
1 mol MgO
x
x
 4.53 grams CO2
40.31 grams MgO 2 mol MgO
1 mol CO2
20.00 grams – 4.53 grams = 15.47 grams left over CO2
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33.) The compound ethyl butyrate has an empirical formula of C3H6O and a molar mass of
116.16 grams. What is the molecular formula for ethyl butyrate?
The mass of the empirical formula is: (12.01g x 3) + (1.01g x 6) + (16.00g x 1) = 58.09g
116.16 grams
1.9997 or about 2
58.09 grams
Therefore, the molecular formula of ethyl butyrate should be the empirical formula with all of its
subscripts multiplied by 2.
C6H12O2
34.) Sodium bicarbonate, better known as baking soda, is used to produce carbon dioxide in
baked goods when heated. The chemical formula for sodium bicarbonate is NaHCO3. What
is the elemental percent composition of carbon in this compound?
The molar mass of sodium bicarbonate is: 22.99g + 1.01g + 12.01g + (16.00g x 3) = 84.01g
The mass of carbon in this compound is 12.01g.
Therefore the elemental percent composition for carbon is simply
12.01 grams C
x 100 14.30% C
84.01 grams NaHCO3
35.) Octyne is a hydrocarbon with a molecular weight of 110.22 grams. The elemental percent
composition of carbon in ocytne is 87.2% by mass. What is the molecular formula of
octyne?
First realize that octyne is a hydrocarbon – composed of only carbon and hydrogen. If you know the
percent composition of carbon, then you can determine the percent composition of hydrogen.
100.0% - 87.2% carbon = 12.8% hydrogen
Then calculate the empirical formula.
87.2 grams C x
1 mol C
 7.26 mol C
12.01 grams C
12.8 grams H x
1 mol H
12.7 mol H
1.01 grams H
9
7.26 mol C
1
7.26 mol
12.7 mol H
 1.75
7.26 mol
When multipled by 4, these two numbers become a whole number ratio of 4:7 therefore the empirical
formula is:
C4H7
This empirical formula has a mass of (12.01g x 4) + (1.01g x 7) = 55.11g
If the molecular weight is 110.22g then:
110.22 grams
2
55.11 grams
Therefore, multiple the subscripts in the empirical formula by 2 to obtain the molecular formula.
C8H14
It makes sense that octyne would have eight of something!
36.) Sorbitol is a sugar alcohol that is roughly as sweet as table sugar (sucrose). It is considered a
nutritive sweetener because while it does have calories, it contains less than regular sugar.
Sorbitol contains the following elemental mass percents: 39.55 % carbon, 7.761% hydrogen,
and 52.69% oxygen. What is the empirical formula for sorbitol?
39.55 grams C x
1 mol C
 3.293 mol C
12.01 grams C
7.761 grams H x
1 mol H
 7.684 mol H
1.01 grams H
52.69 grams O x
1 mol O
 3.293 mol O
16.00 grams O
3.293 mol C
 1.000 C
3.293 mol
7.684 mol H
 2.333 H
3.293 mol
3.293 mol O
1.000 O
3.293 mol
Multiplying all values by 3 will obtain a whole number for C, H, and O. Thus the empirical
formula is:
C3H7O3
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37.) If the molecular weight of sorbitol is 182.2 grams, then what is its molecular formula?
The mass of the empirical formula would be: (12.01g x 3) + (1.01g x 7) + (16.00g x 3) = 91.10g
The molecular weight divided by the mass of the empirical formula is:
182.2 grams
2
91.10 grams
Therefore multiple all the subscripts in the empirical formula by 2 to find the molecular formula.
C6H14O6
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Solubility Rules Made Easy
This chart should help you to better navigate the substances that are soluble
and insoluble in aqueous solutions.
Soluble
Insoluble
Chlorates (-ClO4-)
Acetates (-C2H3O2-)
Sulfates (-SO42-)
Except Ca2+, Ba2+, Hg2+, and Pb2+
Halogens (Cl-, Br-, I-)
Except Hg+, Ag+, Pb2+ (HAPpy)
Nitrates (-NO3-)
Group IA (Li+, Na+, K+, NH4+)
Except with Group IA
Carbonates (-CO32-)
Except with Group IA
Chromates (-CrO42-)
Hydroxides (-OH-)
Except NaOH, KOH, Ba(OH)2, & Ca(OH)2
Phosphates (-PO43-)
Except with Group IA
Sulfides ( –S2-)
Except with Group IA or CaS
If this acronym helps you to remember, then use it. Otherwise, revise and make
your own.
CASHiNG 2CHiPS
Soluble
Insoluble
12
Activity Series
13
Common Polyatomic Ions
+ 1 Charge
Ion
Name
+
NH4
Hg22+
ammonium
mercury (I)
-1 Charge
Ion
Name
-
H2PO3
H2PO4HCO3HSO3HSO4NO2NO3OHC2H3O2CrO2CNCNOCNSMnO4ClOClO2ClO3ClO4BrOBrO2BrO3BrO4IOIO2IO3IO4-
dihydrogen phosphite
dihydrogen phosphate
hydrogen carbonate
hydrogen sulfite
hydrogen sulfate
nitrite
nitrate
hydroxide
acetate
chromite
cyanide
cyanate
thiocyanate
permanganate
hypochlorite
chlorite
chlorate
perchlorate
hypobromite
bromite
bromate
perbromate
hypoiodite
iodite
iodate
periodate
-2 Charge
Ion
Name
2-
HPO3
HPO42CO32SO32SO42S2O32SiO32C22C2O42CrO42Cr2O72C4H4O62MoO42S22-
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hydrogen phosphite
hydrogen phosphate
carbonate
sulfite
sulfate
thiosulfate
silcate
carbide
oxalate
chromate
dichromate
tartrate
molybdate
disulfide
-3 Charge
Ion
Name
3-
PO2
PO33PO43AsO33AsO43-
hypophosphite
phosphite
phosphate
arsenite
arsenate
-4 Charge
Ion
Name
P2O74-
pyrophosphate
This chart will not be provided on the exam but is given here for your reference. It might be useful for your studies.
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