CHM
2045C Module 4 Part I Sample Exam Answers
The
correct answer is:
Ga3+.
Explanation:
Ga3+ : [Ar]
3d10
Solution Reference:
Page 373, Valence Electrons
2.* The
correct answer is:
5.
Explanation:
The crystal lattice energy is the energy given
off in the formation of one mole of solid NaCl from
the combination of one mole of Na+(g) with one mole of Cl-(g).
Solution Reference:
Page 379, Lattice Energy
3.* The
correct answer is:
1 + 2 + 3 + 4 + 5.
Explanation:
Solution Reference:
Page 379, Lattice Energy
* Will not be on test
4. The
correct answer is:
NaF
Explanation:
The crystal lattice energy U is proportional
to the charges on the ions and inversely proportional to the size of the ions
or distance between the ions.
Solution Reference:
Page 379, Lattice Energy
5. The
correct answer is:
NaF
Explanation:
There is a correlation between the melting
point and the crystal lattice energy. The larger the lattice
energy, the higher the melting point.
Solution Reference:
Page 379, Lattice Energy
6. The
correct answer is:
Ca+.
Explanation:
Calcium is in family 2, so we would expect the
calcium ion to be 2+ so that is has a noble gas configuration.
Solution Reference:
Page 377, Bonding in Ionic Compounds
7. The
correct answer is:
H
Explanation:
Since hydrogen is from the first period, the
maximum number of electrons it can have is two.
Solution Reference:
Page 383, The Octet Rule
8. The
correct answer is:
SF4
Explanation:
S has 10 valence electrons around it.
Solution Reference:
Page 383, the Octet Rule
9. The
correct answer is:
18.
Explanation:
Solution Reference:
Page 383, The Octet Rule
10. The
correct answer is:
26.
Explanation:
Solution Reference:
Page 383, The Octet Rule
11.
The
correct answer is:
32.
Explanation:
This problem involves two steps as it is
necessary for a student to know the formula of the perchlorate
ion, ClO4-.
Solution Reference:
Page 383, The Octet Rule
12. The
correct answer is:
NO3-
Explanation:
Find two species with the same number of
valence electrons or draw the Lewis structures.
Solution Reference:
Page 382, Covalent Bonding
13. The
correct answer is:
2.
Explanation:
Solution Reference:
Page 382, Covalent bonding
14. The
correct answer is:
2.
Explanation:
Solution Reference:
Page 382, Covalent Bonding
15. The
correct answer is:
1.
Explanation:
Solution Reference:
Page 382, Covalent Bonding
16. The
correct answer is:
that have no suitable single Lewis
electron-dot formula.
Explanation:
The actual distribution of electrons which
cannot be depicted by a single Lewis structure is an average of the various
Lewis structures that can be drawn for a molecule or ion.
Solution Reference:
Page 392, Resonance
Module 7 Questions 17-18
17.
The
correct answer is:
HBr(g) --> H(g) + Br(g)
Explanation:
The bond dissociation energy is the energy
required to break a gaseous molecule into gaseous atoms.
Solution Reference:
Page 402, Bond Energy
18. The
correct answer is:
473.
Explanation:
NF3(g) --> N(g) + 3F(g) DH = 841 kJ
FN = NF --> 2N(g) + 2F(g) DH = 1033 kJ
The average N-F bond energy is 841/3 =
280 kJ.
Solution Reference:
Page 402, Bond Energy
Module
4 Part II Questions #19-25
19. The
correct answer is:
0 and +6.
Explanation:
Solution Reference:
Page 406, Formal Charges on Atoms
20. The
correct answer is:
trigonal bipyramidal and linear.
Explanation:
Five pairs of electrons are equivalent to a trigonal bipyramidal arrangement
of the electrons. Repulsions are minimized by having three lone pairs of
electrons in the trigonal plane.
Solution Reference:
Page 413, Molecular Shapes
21. The
correct answer is:
NH4+.
Explanation:
Solution Reference:
Page 413, Molecular Shapes
22. The
correct answer is:
OSO.
Explanation:
The lone pair of electrons on sulfur causes a bent molecule. In all the other
molecules in this question, the central atom does not have any lone pairs of
electrons (only bonding pairs). Two regions of electron
density about each central atom.
Solution Reference:
Page 413, Molecular Shapes
23. The
correct answer is:
SO3.
Explanation:
All of the central atoms in the other
molecules have a lone pair of electrons except sulfur.
Solution Reference:
Page 413, Molecular Shapes
24. The
correct answer is:
H2S
Explanation:
H2S is an angular molecule and the
sulfur atom has two lone pairs of electrons.
Solution Reference:
Page 423, Molecular Polarity
25. The
correct answer is:
PF5
Explanation:
PF5 is the only symmetrical
molecule.
Solution Reference:
Page 423, Molecular Polarity