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CHM 134 General Chemistry I
Chapter 9 Worksheet – Dr. Steel
Name
1. Draw a Lewis structure for each of these molecules.
a.
b.
c.
d.
e.
SiCl4
PF3
CS2
HOBr
BrF5
2. Draw all the possible resonance structures (indicated in parentheses) for each of these
molecules.
a.
b.
c.
d.
NO31N2O
SO2
SO3
(3)
(3)
(2)
(3)
3. Indicate whether the bond formed between each of the following pairs would be pure
covalent, polar covalent, or ionic.
a. C and Br
d. Br and F
b. P and As
e. Sr and S
c. K and O
f. N and B
4. Identify the formal charges on each element in these structures.
a.
b.
O
Cl
S
S
C
N
-1
O
c.
F
Cl
Xe
F
O
5. Use formal charges to determine which resonance structure is the one that most
closely resembles the real structure of the molecule indicated:
a.
N
b.
N
O
N
Br
O
N
F
F
F
N
F
F
Br
N
F
F
F
Br
6. Use the table of bond energies to calculate ΔHrxn for each of these reactions.
a. 2 HCl + N2 → Cl2 + HNNH
b. H2CCH2 + 3 O2 → 2 CO2 + 2 H2O
O
F
Answers:
F
Cl
Cl
1. a. SiCl4
Si
Cl
P
F
b. PF3
F
S
C
S
c. CS2
Cl
d. HOBr
F
e.
H
O
F
Br
Br
F
-1
O
2. a.
b.
c.
O
N
O
N
N
O
O
S
O
O
O
d.
O
S
F
O
N
O
O
S
O
O
S
N
N
O
O
O
O
O
c. ionic
f. polar covalent
c. Xe +2
O -1
F 0
5. a. first structure, O has -1 formal charge
b. first structure, everything has a formal charge of 0
6. a. ΔHrxn = + 369 kJ
N
O
b. pure covalent
e. polar covalent
b. S 0
C 0
N -1
-1
O
O
3. a. pure covalent
d. polar covalent
4. a. S +1
O -1
Cl 0
N
N
F
-1
O
O
BrF5
b. ΔHrxn = 1291 kJ
S
O