Name_______________________
Chem 104 Quiz
Chapt 3
Show all work, including any unit conversions for full credit. Potentially useful
information: Pb (lead or plumbum) can be +2 or +4; Mercury can be +1 or +2; CO32- is
carbonate ion.
1. Name the following nine compounds. If naming Cu, Hg, Pb, or Fe, name it twice:
once using the –ic, -ous system, and once using roman numerals.
Cu2SO4
copper (I) sulfate
cuprous sulfate
SnS2
tin (IV) sulfide
Pb(OH)4
lead (IV) hydroxide
plumbic hydroxide
Fe2O3
(NH4)2CO3
iron (III) oxide
ferric oxide
ammonium carbonate
SiCl4
HgI
silicon tetrachloride
mercury (I) iodide
mercurous iodide
N2O
MgCl2
dinitrogen monoxide magnesium chloride
2. Ammonia (NH3) has a boiling point of –33 C and a melting point of –78 C.
Methane (CH4) has the same molecular weight, but has a b.p of -161 C and a
m.p. of –183 C. Given what you know about intermolecular forces, why do
these molecules have such a large disparity in melting and boiling points?
ammonia has polar N-H bonds with partial plus on H and partial minus on N. Because of
this, molecules of ammonia can Hydrogen Bond to each other. H-bonding is the
strongest intermolecular force and takes the most energy (highest temperature) to spread
those molecules apart. Methane only has C-H bonds which are non-polar in nature.
Because of that, methane molecules cannot H-bond or have dipole-dipole attractions.
The only intermolecular force for methane is dispersion forces, the weakest of the
intermolecular forces. So it takes a lot less energy to separate the weakly bonded
methane molecules from each other than it does to separate the strongly bonded ammonia
molecules from each other.
3. Draw Lewis structures for the following. For the first two structures indicate any
polar bonds using either method used in class. The second structure has polar
bonds, but is it a polar molecule? Explain.
Yes, the second structure is a polar molecule. It has polar bonds, and they are arranged
asymmetrically around the central atom.
a. H2CO
H
O
C
H
δδ+ (on the carbon) (my drawing program doesn’t have the “δ” symbol, so I cannot
put it where it belongs on the drawing)
b. NO2-
N
O
O
δ- on each oxygen, δ+ on the nitrogen
c. CCl4
Cl
Cl
C
Cl
Cl
or
Cl
C
Cl
Cl
Cl
δ- on each chlorine, δ+ on the carbon
4. Write formulas for the following compounds:
a. silicon disulfide
SiS2
b. ferrous sulfate
FeSO4
c. carbon tetrachloride
CCl4
d. lithium nitrate
LiNO3