Name: _______________________________
Northwest Vista College
Chem 1311 - General Chemistry I
Fall 2011
Final Exam
Date: Monday Dec 5, 5:00pm – 7:45pm
Section I. Multiple Choice Questions. Circle the letter of the correct answer 3 pts each.
1. Give the number of protons (p), electrons (e), and neutrons (n) in one atom of nickel-62.
A) 28 p, 28 e, 28 n
B) 28 p, 28 e, 34 n
C) 62 p, 28 e, 28 n
D) 62 p, 62 e, 28 n
2. Predict the formula for the binary compound formed between barium and phosphorus.
A) BaP
B) Ba2P
C) BaP2
D) Ba2P3
E) Ba3P2
3. The formula for magnesium sulfate is
A) MnS
B) MgS
C) MnSO3
D) MgSO4
4. What is the average mass, in grams, of one arsenic (As) atom?
A) 5.48 x 10-23 g
B) 33.0 g
C) 74.9 g
D) 1.24 x 10-22 g
E) 8.04 x 1021 g
5. If 0.274 moles of a substance weighs 62.5 g, what is the molar mass of the substance, in
units of g/mol?
A) 2.28 x 102 g/mol
B) 1.71 x 101 g/mol
C) 4.38 x 10-3 g/mol
D) 2.17 x 102 g/mol
E) none of these
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6. Calculate the mass of 3.00 moles of CF2Cl2.
A) 3.00 g
B) 174 g
C) 363 g
D) 1.81 x 1024 g
E) 40.3 g
7. How many carbon atoms are there in 10 lbs of sugar, C12H22O11?
A) 9.6 x 1025 atoms
B) 8.0 x 1024 atoms
C) 159 atoms
D) 4.21 atoms
E) 342 atoms
8. Which of the following compounds is a strong electrolyte?
A) H2O
B) N2
C) CH3COOH (acetic acid)
D) CH3CH2OH (ethanol)
E) KOH
9. Based on the solubility rules, which of the following will occur if solutions of CuSO 4(aq) and
BaCl2(aq) are mixed?
A) CuCl2 will precipitate; Ba2+ and SO42- are spectator ions.
B) CuSO4 will precipitate; Ba2+ and Cl- are spectator ions.
C) BaSO4 will precipitate; Cu2+ and Cl- are spectator ions.
D) BaCl2 will precipitate; Cu2+ and SO42- are spectator ions.
E) No precipitate will form.
10. What is the chemical formula of the salt produced by the complete neutralization of sodium
hydroxide with sulfuric acid?
A) Na2SO4
B) Na2(SO4)3
C) Na(SO4)2
D) NaSO3
E) Na3SO4
11. The oxidation number of Fe in K3Fe(CN)6 is
A) +3
B) +2
C) +1
D) -3
E) -4
12. What element is oxidized in the following chemical reaction?
3Cu + 8HNO3 3Cu(NO3)2 + 2NO + 4H2O
2
A)
B)
C)
D)
E)
Cu
H
N
O
H2O
13. What will happen to the height (h) of the mercury column in the manometer shown below if
the stopcock is opened, given that the atmospheric pressure is 755 mmHg? Note that the
gas in the round bulb contains a gas that supports the given height, h, of mercury
A)
B)
C)
D)
h will decrease because Patmosphere > Pvacuum
h will not change because mercury has a constant density
h will increase because Pgas > Patmosphere
not enough information given to answer the question
14. A sample of nitrogen gas has a volume of 32.4 L at 20°C. The gas is heated to 220ºC at
constant pressure. What is the final volume of nitrogen?
A) 2.94 L
B) 19.3 L
C) 31.4 L
D) 54.5 L
E) 356 L
15. Which of the following processes is endothermic? Hints: a. If the reaction represents a
phase change, connect with adding or removing heat to make the phase change b. If the
reaction is not a phase change, check is bonds are being broken and bonds are being
formed
A)
B)
C)
D)
O2(g) + 2H2(g)  2H2O(g)
H2O(g)  H2O(l)
3O2(g) + 2CH3OH(g)  2CO2(g) + 2H2O(g)
H2O(s)  H2O(l)
16. How many valence electrons does a Phosphorous (P) atom have?
3
A)
B)
C)
D)
E)
2
5
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17. What is the charge on the monatomic ion of nitrogen, the nitride ion?
A) +2
B) +1
C) –1
D) –2
E) –3
18. Which of the elements listed below has the greatest atomic radius?
A) B
B) Al
C) S
D) P
E) Si
19. Which of the following cations has the lowest Lattice energy with the same anion?
A) Li+
B) Na+
C) Be2+
D) K+
E) Rb+
20. Which one of the following is most likely to be an ionic compound?
A) ClF3
B) FeCl3
C) NH3
D) PF3
E) SO3
21. Which one of the following is most likely to be a covalent compound?
A) KF
B) CaCl2
C) SF4
D) Al2O3
E) CaSO4
22. Which of the following solids would have the lowest Lattice energy?
A) KI
B) KBr
C) KCl
D) KF
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23. What type of chemical bond holds the atoms together within a water molecule?
A) Ionic bond
B) Nonpolar covalent bond
C) Polar covalent bond
D) Coordinate covalent bond
24. The total number of lone pairs in the Cl2 atom is ___.
A) 4
B) 5
C) 6
D) 7
E) 8
25. Give the number of lone pairs around the central atom and the molecular geometry of SCl2.
Use Table 10.2 p.416
A) 0 lone pairs, linear
B) 1 lone pair, bent
C) 2 lone pairs, bent
D) 3 lone pairs, bent
E) 3 lone pairs, linear
26. According to the VSEPR theory Use (Table 10.2 p.416), the molecular geometry of
ammonia is
A) linear
B) trigonal planar
C) bent
D) tetrahedral
E) trigonal pyramidal
27. Predict the geometry (Use Table 10.2 p.416) and polarity (Use Table 9.5 p.376) of the CS2
molecule.
A) linear, polar
B) linear, nonpolar (NOTE: nonpolar because the molecule is symmetric, pulls cancel)
C) tetrahedral, nonpolar
D) bent, nonpolar
E) bent, polar
28. A 4.691 g sample of MgCl2 is dissolved in enough water to give 750. mL of solution. What is
the magnesium ion concentration in this solution?
A) 3.70 x 10–2 M
B) 1.05 x 10–2 M
C) 6.57 x 10–2 M (NOTE: conc of Mg2+ same as MgCl2 since they are 1:1 in the formula)
D) 4.93 x 10–2 M
E) 0.131 M
29. Which of these gas molecules have the highest average kinetic energy at 25°C?
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A)
B)
C)
D)
E)
H2
O2
N2
Cl2
All the gases have the same average kinetic energy at the same T
30. What volume of oxygen gas at 320 K and 680 torr will react completely with 2.50 L of NO
gas at the same temperature and pressure?
2NO(g) + O2(g)  2NO2(g)
A)
B)
C)
D)
E)
1.25 L
2.50 L
3.00 L
1.00 L
5.00 L
31. Calculate the volume occupied by 35.2 g of methane gas (CH4) at 25°C and 1.0 atm. R =
0.08206 L⋅ atm/K⋅ mol.
A) 0.0186 L
B) 4.5 L
C) 11.2 L
D) 49.2 L
E) 53.7 L
32. Given H2(g) + (1/2)O2(g)  H2O(l), ΔH° = –286 kJ/mol,
determine the standard enthalpy change for the reaction
2H2O(l)  2H2(g) + O2(g).
A)
B)
C)
D)
E)
ΔH° = –286 kJ/mol
ΔH° = +286 kJ/mol
ΔH° = –572 kJ/mol
ΔH° = +572 kJ/mol
ΔH° = –143 kJ/mol
33. The elements in Group 2A are known by what name?
A) transition metals
B) halogens
C) alkali metals
D) alkaline earth metals
E) noble gases
34. Which one of the following elements is a transition element?
A) antimony
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B)
C)
D)
E)
barium
chromium
potassium
selenium
35. According to the zeroth law of thermodynamics:
A) Energy is neither lost nor gained in any energy transformations.
B) Two bodies in thermal equilibrium with a third, are in thermal equilibrium with each other
C) Energy is conserved in quality but not in quantity.
D) Energy is being created as time passes. We have more energy in the universe now than
when time began.
36. Which of the following pairs of words do not have the same meaning in Thermochemistry
A) heat and temperature
B) exothermic reaction and heat is a product
C) q and the amount of heat transferred
D) bond energy and bond dissociation energy
Brief Answer
37. (2 pts each) Give the name of the following ions:
a) CO32-
_________________________
b) NO3-
_________________________
c) OH-
_________________________
d) NH4+
_________________________
e) PO43-
_________________________
38. (2 pts each) Give the correct formula for the following compounds:
a) calcium chloride
____________________
b) copper(II) oxide
____________________
c) iron(III) oxide
____________________
d) sulfuric acid
____________________
e) sodium dihydrogen phosphate
____________________
39. (2 pts each) Balance the following equations:
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a) _____ C + _____ O2 _____ CO
b) _____ CO + _____ O2  _____ CO2
c) _____ Zn + _____ AgCl  _____ZnCl2 + _____ Ag
d) _____ NaOH + _____ H2SO4  _____ Na2SO4 + _____ H2O
e) _____ C6H12O6 + _____ O2  _____ CO2 + _____ H2O
40. (6 pts) Calculate the percent composition by mass of carbon in Na2CO3.
% mass C = mass C / mass Na2CO3 x 100
%mass C = 12.01 g/molC / 108 g/mol Na2CO3 x 100 = 11.12%
41. (6 pts) What mass of Na2SO4 is needed to prepare 350. mL of a solution having a sodium
ion concentration of 0.125 M? NOTE that there are 2 Na+ ions for every 1 Na2SO4
Answer: rearrange the Molarity formula to find moles of Na+
M Na ions = moles N+ / V in L
Moles Na+ = 0.125 mol/L x .350L = 0.04375 mol Na ion
Then use mole ratio from the formula to find moles Na 2SO4
Moles Na2+ x 1 mole Na2SO4 = Moles of Na2SO4
2 moles Na+
0.04375 mol Na+ x 1 mole Na2SO4 = 0.021875 moles Na2SO4
2 moles Na+
Mass Na2SO4= moles Na2SO4x molar mass = 0.021875 x 142.0428 g/mol
Mass = 31.07g Na2SO4
42. (6 pts) During a titration the following data were obtained. A 10. mL portion of an unknown
monoprotic acid solution was titrated with 1.0 M NaOH; 40. mL of the base were required to
neutralize the sample. What is the molarity of the acid solution?
Answer: This is stoichiometry of an acid base reaction by titration
First write and balance the equation: Use HA for the unknown acid
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HA + NaOH  NaA + H2O
Then use this relationship for the reaction stoichiometry
Macid Vacid x mole ratio of base to acid = MbaseVbase
M of HA x .010LHA x 1mole NaOH = 1.0M NaOH x 0.040L NaOH
1 mole HA
Solve for M of HA
M HA = 1.0M NaOH x 0.040L NaOH x 1molHA = 4.0M
.010LHA x 1mole NaOH
43. (6 pts) Calculate the number of moles of gas contained in a 10.0 L tank at 22°C and 105
atm. R = 0.08206 Latm / mol K
Answer: Use Ideal Gas Law
n=?
V = 10.0L
T = 22°C + 273 = 295K
P = 105atm
PV = nRT which rearranges to n = PV/RT
n = 105atm x 10.0L / (0.08206 Latm/mol K x 295K) = 43.37 moles
44. (6 pts) How many liters of chlorine gas at 25°C and 0.950 atm can be produced by the
reaction of 12.0 g of MnO2 with excess HCl(aq) according to the following chemical
equation?
MnO2(s) + 4HCl(aq)  MnCl2(aq) + 2H2O(l) + Cl2(g)
Answer: First find the number of moles Cl2 formed from the reaction
12.0 g MnO2 x 1mole MnO2
x 1mol Cl2
= 0.138 mol Cl2
86.9369 g MnO2
1 mol MnO2
Then use these number of moles Cl2 as n for the ideal gas law and solve for Volume
V = nRT / P = (0.138 mol Cl2 x 0.08206 Latm /mol-K x 298K) / .950atm = 3.55 L Cl2
45. (6 pts) How much heat is required to raise the temperature of 2,500 g of water from 27°C to
72°C? The specific heat of water is 4.184 J/g·°C.
Answer: Use q = m s T
q = 2,500g x 4.184 J/g·°C x (72 – 27 °C) = 4.707 x 105 J
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46. (6 pts) When 0.560 g of Na(s) reacts with excess F2(g) to form NaF(s), 13.8 kJ of heat is
evolved at standard-state conditions. What is the standard enthalpy of formation (ΔH°f) of
NaF(s)? Note that the units of ΔH°f are in kJ/mole and the heat evolved in the reaction is
given in kJ.
Answer: First write and balance the equation
2Na (s) + F2 (g) 2NaF (s) 13.8kJ
Then calculate # moles NaF from the given grams of Na:
0.560 g Na x 1mole Na x 2 moles NaF = .0244 moles NaF
22.99g Na 2 moles Na
ΔH°f =
13.8kJ / .0244 mol = 565.57 kJ/mol
47. (6 pts) Calculate the standard enthalpy change for the reaction
2C8H18(l) + 17O2(g)  16CO(g) + 18H2O(l).
Given:
2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O(l)
2CO(g) + O2(g)  2CO2(g)
ΔH° = –11,020 kJ/mol
ΔH° = –566.0 kJ/mol
.
Answer: Keep eqn 1 as is, reverse eqn 2 and multiply by 8. Then add both eqns and simplify.
(eqn 1) 2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O(l)
(eqn 2) 8(2CO2(g)  2CO(g) + O2(g) )
___________________________________
2C8H18(l) + 17O2(g)  16CO(g) + 18H2O(l)
ΔH° = –11,020 kJ/mol
ΔH° = - (–566.0 kJ/mol) x 8
________________
- 6492 kJ/mol
48. (4pts) Write balanced molecular and net ionic equations for the reaction that occurs when
aqueous solutions of potassium iodide and lead(II) nitrate are combined.
Answers:
2KI(aq) + Pb(NO3)2 (aq)  PbI2 (s) + 2KNO3(aq)
2I- (aq) + Pb2+ (aq)  PbI2 (s)
49. Calculate the amount of work done against an atmospheric pressure of 1.00 atm when
500.0 g of zinc dissolves in excess acid at 30.0°C. Hint: First find by stoichiometry, the
number of moles of gas formed in the reaction. Then use the number of moles of gas
formed to find the volume of the gas formed. Last, the volume of the gas formed in the
reaction is V. Use this volume in the work formula
.
Answer
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Zn(s) + 2H+(aq)  Zn2+(aq) + H2(g)
500.0g Zn x
1mol Zn
65.4094Zn
x 1 mol H2
1 mol Zn
= 7.644mol H2 = n mol H2
You do the calculations here:
V H2 = n mol H2 x R x T / P
W = - P V = - 1atm x VH2
Change from L-atm to units of Joules:
Answer above x 101.3 Joules/ L-atm
50. (5 pts) Write the Lewis structure for OF2.
51. (6 pts) Write a Lewis structure for the nitrate ion, NO3–
52. Short Answer Type (6 pts):
REACTION A
REACTION B
Given the two reaction profiles above,
1. Using complete sentences, compare and contrast Reaction A and Reaction B in terms of the following
parameters:
a. Relative energy content of reactants and products
b. amount of energy needed to make the reaction happen (Energy of activation)
c. net amount of energy released or absorbed (exo or endo)
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Answer:
Reaction A: Reactants are at a higher energy level than products. 100 kJ of energy are required for
activation and 100kJ are released. The reaction is exothermic
Reaction B: Products are at a higher energy content than reactants. 250 kJ are required to activate the
reaction. A total of 100 kJ are absorbed by the reaction. It is endothermic.
2. Choose one of the hypothetical reactions in the diagrams above and write a general thermochemical
equation for it using the value provided for H
Answer
Reaction A : A + B  C + D H = -100kJ
OR
Reaction B: A + B  C + D H = +100kJ
3. Which of the two reactions do you think would be more difficult to carry out and why?
Reaction B because it requires a greater amount of energy for activation.
END of REVIEW
Some prefixes used with SI Units
tera (T)
1012
centi (c)
10-2
giga (G)
109
milli (m)
10-3
mega (M)
106
micro (μ)
10-6
kilo (k)
103
nano (n)
10-9
deci (d)
10-1
pico (p)
10-12
Useful Conversion Factors & Relationships
1 lb = 453.6 g
1 gal = 3.785 L
1 in = 2.54 cm
1 mi = 1.609 km
1 atm = 760 mmHg = 760 torr = 101,325 N/m 2 = 101,325 Pa
1 cal = 4.184 J
1 L⋅ atm = 101.325 J
C  (  F  32) 
5
9
9
 F  C  32
5
K C 273.15
Fundamental Constants
Avogadro’s number
6.0221415 x 1023
Proton mass
1.672621 x 10-24 g
Neutron mass
1.67492728 x 10-24 g
Electron mass
9.1093826 x 10-28 g
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L  atm
K  mol
Gas constant (R)
0.082057
Speed of light in a vacuum
2.99792458 x 108 m/s
Planks constant (h)
6.6260693 x 10-34 J ⋅ s
Rydberg constant (RH)
2.179872 x 10-18 J
Electron charge (e)
1.60217653 X 10-19 C
Faraday constant (F)
96,485.3383 C/mol e-
Solubility rules for ionic compounds in water
Soluble ionic compounds
Insoluble ionic compounds
alkali metals & NH4+ compounds.
CO32-, PO42-, CrO42- & S2- compounds except those
of alkali metals & NH4+.
NO3-, HCO3-, ClO3- compounds.
OH- except compounds containing alkali metal ions
& Ba2+
Halides except except Ag+, Pb2+, Hg22+.
SO42- compounds except Ag+, Ca2+, Sr2+, Ba2+,
Hg22+, Pb2+.
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