Chem 100 Practice Exam III
For all questions, show all work and use the proper number of significant figures where
applicable. Potentially useful information:
CO32- is carbonate, CN- is cyanide,
MnO4- is permanganate
Soluble
K , Li , Na+, NH4+, NO3-, CH3COOHalides (Halogens)
Sulfates
+
+
Insoluble
Carbonates
Phosphates
Sulfides
Hydroxides
Exceptions:
none
Ag+, Pb2+, Hg+
Ba2+, Sr2+, Pb2+, Hg+
Exceptions:
Group 1A and NH4+
Group 1A and NH4+
Group 1A, Ca2+, Ba2+, Sr2+ and NH4+
Group 1A, Ca2+, Ba2+, Sr2+ and NH4+
(CO32-)
(PO43-)
(S2-)
(OH-)
1. Name the following or give the formula. If hydrogen and halogen, name as an acid
2.
a. ammonium nitrate
b. vanadium (V) carbonate
NH4NO3
V2(CO3)5
c. Cu3(PO4)2
d. FeSO4
copper (II) phosphate
iron (II) sulfate
e. N2O
f.
dinitrogen monoxide
nickel (II) hydroxide
g. Pb(MnO4)2
h. HF
lead (II) permanganate
hydrofluoric acid
i. PBr5
j. H2O (not the common name!)
phosphorus pentabromide
dihydrogen monoxide
Ni(OH)2
Balance the equations below.
3 NaOH (aq) +
1 H3PO4 (aq) →
3 H2O (aq)
1 Fe2O3 (s)
3 CO (g)
→
+
+
2 Fe (s)
1 Na3PO4 (aq)
+
3 CO2 (g)
1 B2H6 (g)
+
→
3 O2 (g)
2 HBO2 (g)
+
2 H2O (g)
4 C3H5O9N3 (l) (nitroglycerin) →
12 CO2 (g) +
6 N2 (g) + 1 O2 (g)
+
10 H2O (g)
3. Draw Lewis structures for the two molecules CS2 and SiBr2O. What is the shape around the
central atom in each molecule?
Can’t draw on this computer, but carbon disulfide is linear, carbon double bonded to each
sulfur and two lone pairs on each sulfur.
Silicon in center, double bond to oxygen, each bromine has a single bond to silicon. Each Br
with 3 lone pairs, O w/ 2 lone pairs and this is trigonal planar.
4. For the molecules above, indicate any polar bonds and tell me whether the molecule itself is
polar or not.
1st molecule, δ+ on the C, δ- on both S’s; molecule is non-polar because both bonds in
linear molecule are polar
2nd molecule, δ+ on Si, δ- on both Br’s and O; according to our chem. 100 theory, this
molecule is non polar because it is trigonal planar and has three polar bonds (technically, this is
polar because the three polar bonds are not all equal – but this is more detail than I said you
would be responsible for)
5. Examine the reactions below. For each reaction that produces a precipitate, tell me what the
precipitate is. If no solid is produced, write NR. Pick one of the reactions that does make a
precipitate and write molecular, total ionic, and net ionic equations for that reaction.
a.
Ba(NO3)2 (aq)
+
NH4OH (aq) →
b.
SrCl2 (aq)
+
Na2SO4 (aq) →
NR
SrSO4 (s) + 2 NaCl (aq)
Sr2+ (aq) + 2 Cl- (aq) + 2 Na+ (aq) + 1 SO42- (aq) → SrSO4 (s) + 2 Na+ (aq) + 2 Cl- (aq)
Sr2+ (aq) + SO42- (aq) →
c.
SrSO4 (s)
4 K3PO4 (aq) + 3 Pb(CH3COO)4 (aq) → 1 Pb3(PO4)4 (s) + 12 KCH3COO (aq)
12 K+ (aq) + 4 PO43- (aq) + 3 Pb4+ (aq) + 12CH3COO- (aq) → 1 Pb3(PO4)4 (s) + 12K+ (aq) + 12
CH3COO- (aq)
3 Pb4+ (aq) + 4 PO43- (aq) → 1 Pb3(PO4)4 (s)
6. Balance the following reactions.
1 Ag2S (s) +
1 BaCl2(aq) +
6 CO2 (g) +
2 HCl (aq) +
2 HCl (aq)

1 Na2CO3(aq) 
6 H2O (l)

1 CaCO3 (s) 
2 AgCl (s) +
1 BaCO3 (s) +
1 C6H12O6 (s) +
1 CaCl2 (aq) +1 CO2 (g) +
1 H2S (g)
2 NaCl (aq)
6 O2 (g)
1 H2O (l)