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Name (please print) __________________________
Student Number______________________
Signature_____________________________________
UNIVERSITY OF SASKATCHEWAN
DEPARTMENT OF CHEMISTRY
Chemistry 114.3 Midterm Examination
Instructors: Dr. I.J. Burgess and R.P. Steer
October 19th, 2013
Time : 90 minutes
Instructions:
1. This is a closed-book examination.
2. This Examination Paper has 12 pages, including a data-sheet and this cover page.
3. Each question is worth 1 marks
4. Questions should be answered on the op-scan sheet. Before starting the
examination, fill out the top of this Examination Paper and the op-scan sheet, and code
your student number on the op-scan sheet in HB pencil. At the end of the examination,
place the op-scan sheet on top of this Examination Paper and hand in both together.
5. The use of simple (maximum two-line) calculators is allowed but the use of laptops,
PDAs, electronic dictionaries, cellphones, iPods and similar personal audio devices is
forbidden.
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1. Which of the following is an example of the law of multiple proportions?
A) A sample of chlorine is found to contain three times as much Cl-35 as Cl-37.
B) Two different compounds formed from carbon and oxygen have the following mass
ratios: 1.33 g O: 1 g C and 2.66 g O: 1 g C.
C) Two different samples of table salt are found to have the same ratio of sodium to
chlorine.
D) The atomic mass of bromine is found to be 79.90 amu.
E) Nitrogen dioxide always has a mass ratio of 2.28 g O: 1 g N.
2. What does "X" represent in the following symbol?
80
35 X
A) mercury
B) chlorine
C) scandium
D) bromine
E) selenium
3. What species is represented by the following information?
number of protons = 12, number of neutrons = 14, number of electrons = 10
A) Si4+
B) Mg
C) Ne
D) Si
E) Mg2+
4. Calculate the atomic mass of gallium if gallium has 2 naturally occurring isotopes with
the following masses and natural abundances:
Ga-69
Ga-71
68.9256 amu
70.9247 amu
60.11%
39.89%
A) 69.72 amu
B) 69.93 amu
C) 70.00 amu
D) 69.80 amu
E) 70.68 amu
5. How many atoms are in 2.50 moles of CO2?
A) 4.52 x 1024 atoms
B) 1.52 x 1024 atoms
C) 5.02 x 1023 atoms
D) 3.01 x 1024 atoms
E) 7.53 x 1023 atoms
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6. According to the following balanced reaction, how many moles of HNO3 are formed
from 8.44 moles of NO2 if there is plenty of water present?
3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g)
A) 2.81 moles HNO3
B) 25.3 moles HNO3
C) 8.44 moles HNO3
D) 5.63 moles HNO3
E) 1.83 moles HNO3
7. How many grams of oxygen are formed when 6.21 moles of KOH are formed?
4 KO(s) + 2 H2O(l) → 4 KOH(s) + O2(g)
A) 19.9 g O2
B) 27.9 g O2
C) 49.7 g O2
D) 3.59 g O2
E) 11.7 g O2
8. Consider the following balanced reaction. What mass (in g) of CO2 can be formed
from 288 mg of O2? Assume that there is excess C3H7SH present.
C3H7SH(l) + 6 O2(g) → 3 CO2(g) + SO2(g) + 4 H2O (g)
A) 0.396 g CO2
B) 0.209 g CO2
C) 0.792 g CO2
D) 0.126 g CO2
E) 0.198 g CO2
9. Give the theoretical yield, in moles, of CO2 from the reaction of 4.00 moles of C8H18
with 4.00 moles of O2.
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O
A) 0.640 moles
B) 64.0 moles
C) 2.56 moles
D) 16.0 moles
E) 5.12 moles
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10. Give the percent yield when 28.16 g of CO2 are formed from the reaction of 8.000
moles of C8H18 with 4.000 moles of O2.
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O
A) 20.00%
B) 25.00%
C) 50.00%
D) 12.50%
E) 16.00%
11. How many milliliters of a 0.184 M NaNO3 solution contain 0.113 moles of NaNO3?
A) 543 mL
B) 163 mL
C) 614 mL
D) 885 mL
E) 326 mL
12. Determine the molarity of a solution formed by dissolving 468 mg of MgI2 in enough
water to yield 50.0 mL of solution.
A) 0.0297 M
B) 0.0337 M
C) 0.0936 M
D) 0.0107 M
E) 0.0651 M
13. According to the following reaction, what mass of PbCl2 can form from 235 mL of
0.110 M KCl solution? Assume that there is excess Pb(NO3)2.
2 KCl(aq) + Pb(NO3)2 (aq) → PbCl2(s) + 2 KNO3(aq)
A) 7.19 g
B) 3.59 g
C) 1.80 g
D) 5.94 g
E) 1.30 g
14. Which of the following solutions will have the highest electrical conductivity?
A) 0.045 M Al2(SO4)3
B) 0.050 M (NH4)2CO3
C) 0.10 M LiBr
D) 0.10 M NaI
E) 0.10 M KF
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15. Give the net ionic equation for the reaction (if any) that occurs when aqueous
solutions of Na2CO3 and HCl are mixed.
A) 2 H+(aq) + CO32-(aq) → H2CO3(s)
B) 2 Na+(aq) + CO32-(aq) + 2 H+(aq) + 2 Cl-(aq) → H2CO3(s) + 2 NaCl(aq)
C) 2 H+(aq) + CO32-(aq) → H2O(l) + CO2(g)
D) 2 Na+(aq) + CO32-(aq) + 2 H+(aq) + 2 Cl-(aq) → H2CO3(s) + 2 Na+(aq) + 2 Cl-(aq)
E) No reaction occurs.
16. The titration of 25.0 mL of an H2SO4 solution of unknown concentration requires
83.6 mL of 0.12 M LiOH solution to reach the equivalence point. What is the
concentration of the H2SO4 solution (in M)?
A) 0.20 M
B) 0.40 M
C) 0.10 M
D) 0.36 M
E) 0.25 M
17. What is the oxidation number of oxygen in Na2O2 ?
A) -2
B) -1
C) +1
D) +2
E) 0
18. What is true about the following reaction.?
Ni(s) + 2 AgClO4(aq) → Ni(ClO4)2(aq) + 2 Ag(s)
A) Ag is being reduced
B) Ni is being oxidized
C) Cl has an oxidation number of +7
D) All of A, B and C are true
E) This is not an oxidation-reduction reaction.
19. Which of the following is a STRONG acid?
A) C6H5CO2H
B) HCN
C) HClO4
D) NH4+
E) H2O
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20. Calculate the hydroxide ion concentration in an aqueous solution with a pH of 9.85 at
25°C.
A) 7.1 × 10-5 M
B) 4.2 × 10-10 M
C) 8.7 × 10-10 M
D) 6.5 × 10-5 M
E) 1.4 × 10-10 M
21. Which of the following solutions would have the highest pH? Assume that they are
all 0.10 M in acid at 25oC. The acid is followed by its Ka value.
A) HF, 3.5 × 10-4
B) HCN, 4.9 × 10-10
C) HNO2, 4.6 × 10-4
D) HCHO2, 1.8 × 10-4
E) HClO2, 1.1 × 10-2
22. Calculate the pH of a solution that contains 2.4 × 10-5 M H3O+ at 25°C.
A) 2.40
B) 9.38
C) 4.62
D) 11.60
E) 4.17
23. Mercury has a density of 13.5 x 103 kg/m3. How much does exactly 1 mL of mercury
weigh ?
A) 13.5 kg.
B) 1.35 kg
C) 135 g
D) 13.5 g
E) 1.35 g
24. Which of the following statements is most correct ?
A) accuracy is a measure of how close an experimental result is to the correct answer.
B) the reproducibility of a measurement defines its precision.
C) the ability to measure small differences defines the precision.
D) answers A and B are both correct.
E) answers A and C are both correct.
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25. Combustion analysis of a hydrocarbon produced 33.01 g of CO2 and 13.51 g of H2O.
What is the correct empirical formula of the hydrocarbon ?
A) CH
B).CH2
C) CH3
D) CH4
E) none of the above
26. A mixture of KCl and NaCl has a mass of 1.00 g and is found to contain 0.509 g of
Cl. What is the mass of NaCl in the mixture ?
A) 0.491 g
B) 0.206 g
C) 0.255 g
D) 0.439 g
E) 0.561 g
27. The balanced chemical equation for the reaction of barium chlorate and sulfuric acid
to produce chloric acid and barium sulfate is.
A) Ba  ClO 2  aq   H 2 SO4  aq   2 HClO  aq   BaSO4  aq 
B) Ba  ClO2 2  aq   H 2 SO4  aq   2HClO2  aq   BaSO4  aq 
C) Ba  ClO3 2  aq   H 2 SO4  aq   2HClO3  aq   BaSO4  aq 
D) Ba  ClO4 2  aq   H 2 SO4  aq   2HClO4  aq   BaSO4  aq 
E) Ba  ClO4 2  aq   H 2 SO4  aq   2HCl  aq   BaSO4  aq   4O2  g 
28. How many molecules are in 32.0 g of O2 ? Choose the best answer.
A) 1.66 x 10-24
B) 1.20 x 1025
C) Twice the numeric value of Avogadro’s number.
D) Half the numeric value of Avogadro’s number.
E) Avogadro’s number
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29. How many of the following are ionic compounds ?
i)
NaCl
ii)
Cu
iii)
H2O
iv)
nickel (II) acetate
A) 0
B) 1
C) 2
D) 3
E) 4
30. How many of the following are molecular compounds ?
i)
ScCl2
ii)
NH4Cl iii)
NH3
iv)
ammonium phosphate
A) 0
B) 1
C) 2
D) 3
E) 4
31. Which of the following contains the largest number of hydrogen atoms ?
A) one mole of CH4
B) 30.0 g of C2H6
C) 6.022 x 1022 molecules of C6H6
D) 22.0g of C3H8
E) they all have equal amounts of hydrogen atoms.
32. Which element has the highest percent mass in C6H3Cl2NO3 ?
A) C
B) H
C) Cl
D) N
E) O
33. An ideal gas occupies 22.2 L at standard temperature and pressure. How many moles
of gas are in the sample ?
A) not enough information is provided to answer the question
B) 1 mole
C) 1/22.2 moles
D) 273 moles
E) 22.2 moles
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34. Determine the volume of O2 (at STP) formed when 50.0 g of KClO3 decomposes
according to the following reaction.
2 KClO3(s) 
2 KCl(s) + 3 O2(g)
A) 9.14 L
B) 8.22 L
C) 12.3 L
D) 13.7 L
E) 14.6 L
35. Calculate the density in g/L of CO2 gas at 27 ºC and 0.50 atm pressure.
A) 1.12 g/L
B) 9.9 g/L
C) 0.89 g/L
D) 46 g/L
E) 1.90 g/L
36. Which of the following statements is correct with respect to an ideal gas?
A) For an ideal gas, there are no forces of interaction between the individual gas
particles.
B) For an ideal gas, the volume(s) of the gas particles are considered to be zero as the
particles have no volume.
C) All gases behave as ideal gases at the limit of low temperatures and small volumes
D) Both A) and B) are true but C) is not true.
E) All of A), B) and C) are true.
37. A gas at a pressure of 740 mm Hg at 20 ºC and volume of 1.00 L has a mass of 1.134
g. If the empirical formula of the compound is CH2 what is its molecular formula?
A) CH2
B) CH4
C) C2H4
D) C3H6
E) C4H8
38. A mixture of N2 and Cl2 has partial pressures 0.300 atm and 0.700 atm
respectively at 25 ºC. A volume of 1.05 L contains how many grams of nitrogen?
A) 1.20 g
B) 0.361 g
C) 0.841 g
D) 2.92 g
E) not enough information is provided to answer the question.
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39. The van der Waals equation of state
A) can be used to calculate the properties of a gas under nonideal conditions.
B) is correct only at high pressures.
C) accounts for finite volume effects but not intermolecular forces
D) accounts for intermolecular forces but not finite volume effects.
E) explains why real gases never obey Charles’ Law.
40. If “x” moles of gas are at an initial temperature, T and pressure, P, how can the
gas volume be doubled ? Assume ideal gas behavior.
A) double the absolute temperature while keeping x and P constant.
B) cool the gas so that its T (in oC) halves while keeping x and P constant.
C) keep x constant but double the pressure (in atm) under isothermal conditions.
D) add more gas so that the mass doubles while keeping T and P constant.
E) remove half the moles of gas while keeping T and P constant.
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Values of numerical constants and conversion factors:
1 L atm = 101.3 J
speed of light in a vacuum, c = 3.00 x 10 8 m s-1
Universal gas constant R = 8.314 J K-1 mol-1 = 0.08206 L atm K-1 mol-1
Standard temperature and pressure: P = 1 atm = 760 mm Hg = 760 Torr = 101.325 kPa
T = 273.15 K = 0 °C
Avogadro’s number: NA = 6.022 x 1023 mol-1
Potentially useful equations:
E = q + w
H = E + PV
w = –PextV
Hrxn = pHf(prod) – rHf(react)
E = mc2
ln(ex) = x
q = mCT
qrxn = – qcal
PV = nRT
ln(x) = 2.303log10(x)
F = ma
E = ½ mv2
KW =[H3O+][OH-] = 1.0 x 10-14
For: aA + bB + …  cC + dD + … , Kc = ([C]c[D]d…)/([A]a[B]b…)
y = mx + b
For the equation: ax2 + bx + c = 0,