- (D) 8.00 g of oxygen atomsrepresent 0.500 mole.
..
..
mole O /gO
mole Xmoles O
gOgX
0 500 g X mole X800
12
80044 0
##= 17618. (B) Remember that in an endothermic process, energy is being absorbed. All endothermic
changes are defined with a + sign. Going from the liquid to the gaseous phase requires en-
ergy and thus is endothermic.
19. (A) Remember Boyle’s law: As the volume decreases (at constant temperature), the pres-
sure increases.
20.(A) The atomic radius decreases because of increasing effective nuclear charge and elec-
trostatic attraction. There are more protons and electrons, so electrons are needed to create
a complete shell; thus, there is an increase in electronegativity.- (C) Refer to the table entitled “Geometry and Hybridization Patterns,” page 82.
22.(E) NH 3 is a neutral ligand; the bromide and the chloride ion both have a −1 charge.
Cobalt would have to have a +3 charge in this compound for the complex compound to be
electrically neutral.
Naming Complex Compounds
- Name the cation before the anion.
2.Name the ligands before the metal ion.
3.For the ligands:
a. Add −o to the root name of the anion — in this case, bromo.
b. Use aquo for H 2 O, amine for NH 3 , carbonyl for CO, nitrosyl for NO.
c. Use the name of the ligand for other neutral ligands.
d. Name the ligands alphabetically.
4.Use prefixes to denote the number of ligands of the same kind present.
a. mono-, di-, tri-, tetra-, penta-, hexa- (here, pentaamine).
b. bis-, tris-, tetrakis for complex ligands.
5.Use Roman numerals to designate the oxidation state of the metal ion [cobalt(III)].
6.Add -ate as a suffix to the metal if the complex ion is an anion.
23.(D) Hydrogen bonding is a very strong intermolecular force that occurs between an H
atom of one molecule that is bonded to either a fluorine, an oxygen, or a nitrogen atom. In
choice (D), the hydrogens are bonded to carbon, not to F, O, or N.
Answers and Explanations for the Practice Test