Chem 1025 Final Exam Page 2
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213. A system absorbs 462 kJ of heat and the surroundings do 593 kJ of work on the system. What is the change in internal
energy of the system?
(1) 131 kJ
(2) -1055 kJ
(3) -131 kJ
(4) 1055 kJ
(5) Not enough information
14. The explosive nitroglycerin (C
H
N
O
) decomposes rapidly upon ignition according to the following equation:
3
5
3
9
4 C
H
N
O
(l) → 12 CO
(g) + 10 H
O(g) + 6 N
(g) + O
(g)
∆H
= -6132 kJ
3
5
3
9
2
2
2
2
rxn
Calculate the standard enthalpy of formation (∆H
) for nitroglycerin. For CO
(g), ∆H
= -393.5 kJ/mol. For H
O(g),
f
2
rxn
2
∆H
= -241.82 kJ/mol.
rxn
(1) -1008 kJ/mol
(2) -1714 kJ/mol
(3) 4791 kJ/mol
(4) -114 kJ/mol
(5) 1008 kJ/mol
15. In a coffee-cup calorimeter, 3.19 g of NH
NO
is dissolved in enough water to make 35.0 mL of solution. The initial
4
3
o
o
temperature is 27.3
C and the final temperature is 22.6
C. Calculate the change in enthalpy for the reaction in
kJ/mol. (Assuming 1.0 g/mL as the density of the solution).
(1) -63 kJ/mol
(2) 17.1 kJ/mol
(3) -688 kJ/mol
(4) -17.1 kJ/mol
(5) 688 kJ/mol
16. Determine the bond energy of a Cl-Cl bond given the following information.
o
H
C-H(g) + Cl-Cl(g) → H
C-Cl(g) + H-Cl(g)
∆H
= -113 kJ
3
3
rxn
Bond
Bond Energy (kJ/mol)
H-Cl
431
C-Cl
339
H-C
414
(1) 395 kJ/mol
(2) -170 kJ/mol
(3) 205 kJ/mol
(4) -431 kJ/mol
(5) 243 kJ/mol
17. Determine whether a bond between each of the following pairs of atoms would be pure covalent, polar covalent, or
ionic:
B and O
Sr and O
Ni and Ni
As and Br
Cs and Cl
(1) Pure, Ionic, Pure, Ionic, Ionic
(2) Polar, Polar, Pure, Ionic, Ionic
(3) Polar, Ionic, Pure, Polar, Ionic
(4) Polar, Polar, Ionic, Pure, Ionic
(5) Pure, Ionic, Pure, Polar, Polar
+
18. What is the formal charge of the central atom in the hydronium ion [H
O]
?
3
(1) -2
(2) -1
(3) 0
(4) +1
(5) +2
19. How many resonance structures are possible for nitric acid, HNO
?
3
(1) 0
(2) 1
(3) 2
(4) 3
(5) 4
20. Use the Born-Haber cycle and the following reactions to calculate the electron affinity of chlorine.
o
Na(s) + ½ Cl
(g) → NaCl(s)
∆H
= -411 kJ/mol
2
f
o
Na(g) → Na(s)
∆H
= -108 kJ/mol
f
o
½ Cl
(g) → Cl(g)
∆H
= +122 kJ/mol
2
f
+
-
o
Na
(g) + e
→ Na(g)
∆H
= -496 kJ/mol
f
+
-
o
Na
(g) + Cl
(g) → NaCl(s)
∆H
= -788 kJ/mol
f
(1) -349 kJ/mol
(2) -1103 kJ/mol
(3) 859 kJ/mol
(4) -1681 kJ/mol
(5) -859 kJ/mol
21. What are the electron geometry and the molecular geometry of ClF
?
3
1) Trigonal planar, Trigonal Planar
2) Tetrahedral, Trigonal Planar
3) Tetrahedral, Trigonal Pyramidal
4) Trigonal Bipyramidal, T-Shaped
5) Octahedral, Square Pyramid
+
22. Determine whether the following molecules or ion is polar (p) or nonpolar (np): NH
, H
O, XeF
, CH
CH
4
2
2
3
3
1) np, np, np, np
2) p, p, p, np
3) p, p, np, np
4) p, np, np, np
5) np, p, np, np
23. Predict the molecular shape and give the approximate bond angles of the SBr
molecule.
2
(A) Linear, 180°
(B) Bent, 109.5
(C) Tetrahedral, 109.5°
(D) Trigonal pyramidal, 109.5°
(E) Trigonal planar, 120°
24. Which of the following liquids are likely to be soluble with water: methanol (CH
OH), pentanol (C
H
OH), hexane
3
5
11
(C
H
), and acetic acid (CH
CO
H)?
6
14
3
2
(A) Methanol and pentanol
(B) Methanol and acetic acid
(C) Methanol and hexane
(D) Hexane and pentanol
(E) Acetic acid and hexane
25. Which of the following substances will exhibit dipole-dipole intermolecular forces?
(A) C
H
(B) SO
(C) CO
(D) F
(E) Ar
2
4
2
2
2
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