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Chem 167 Final exam review
Supplemental Instruction
Iowa State University
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Ugerah & Sean
Chem 167
Dr Meyer and Dr Bonaccorsi
10/11 December, 2016
1. Consider the following reaction:
What is the:
a.
b.
c.
d.
Acid
Base
Conjugate acid
Conjugate base
1. The atomic mass of copper is 63.55 amu. There are only two isotopes of copper, 63Cu
with a mass of 62.94 amu and 65Cu with a mass of 64.93 amu. What is the percentage
abundance for each of these two isotopes?
2. Name the compound or give the molecular formula.
a. sulfur hexafluoride
b. lead (II) sulfate
c. Fe(NO3)2
d. Br2O5
3. Balance the following equations. Then write the total ionic equation and net ionic
equation.
a. Zn(s) + HCl(aq)  H2(g) + ZnCl2(aq)
b. HNO3(aq) + CaCO3(s)  Ca(NO3)2(aq) + H2O(l) + CO2(g)
4. How many grams of solute are contained in 255 mL of 0.158 M FeCl3?
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5. How many milliliters of 3.00 M H2SO4 are required to produce 1.50 L of 0.250 M
solution?
6. If 8.4 moles of disiline, Si2H6, are combined with 15.1 moles of O2, which is the limiting
reactant?
2Si2H6 + 7O2  4SiO2 + 6H2O
7. Magnesium nitride forms in a side reaction when magnesium metal burns in air. This
reaction may also be carried out in pure nitrogen.
3Mg(s) + N2(g)  Mg3N2(s)
If 18.4 g of Mg3N2 forms from the reaction of 20.0 g of magnesium with excess nitrogen,
what is the percentage yield?
8. A sample of CO2 gas has a pressure of 56.5 mm Hg in a 125 mL flask. The sample is
transferred to a new flask, where it has a pressure of 62.3 mm Hg at the same
temperature. What is the volume of the new flask?
9. A gas bubble forms inside a vat containing a hot liquid. If the bubble is originally at 68°C
and a pressure of 1.6 atm with a volume of 5.8 mL, what will its volume be if the
pressure drops to 1.2 atm and the temperature drops to 31°C?
10. In an experiment, a mixture of gases occupies a volume of 3.00 L at a temperature of
22.5° C. The mixture contains 14.0 g of water, 11.5 g of oxygen, and 37.3 g of nitrogen.
Calculate the total pressure and the partial pressure of each gas.
11. The photoelectric effect can be used in engineering designs for practical applications.
For example, infrared goggles used in night-vision applications have materials that give
an electrical signal with exposure to the relatively long wavelength IR light. If the energy
needed for signal generation is 3.5x10-20 J, what is the minimum wavelength and
frequency of light that can be detected?
12. Which one of the following represents an acceptable possible set of quantum numbers
(in the order n, l, ml, ms) for an electron in an atom?
a. 2, 1, -1, +1/2
b. 2, 1, 0, 0
c. 2, 2, 0, +1/2
d. 2, 0, 1, -1/2
e. 2, 0, 2, +1/2
13. [Ar]4s23d104p3 is the electron configuration of an atom of which element?
14. What are the trends on the periodic table for electronegativity, ionization energy, and
atomic radius?
15. Select the smaller member of each pair:
a. N and N3b. Ba and Ba2+
c. Se and Se2d. Co2+ and Co3+
16. Given the molecule for glycine:
a. What is the hybridization at the N atom?
b. Estimate the O-C-O bond angle.
17. What is the coordination number for (a) simple cubic (b) body-centered cubic (c) facecentered cubic?
18. Polonium is the only metal that forms a simple cubic crystal structure. Use the fact that
the density of polonium is 9.32 g/cm3 to calculate its atomic radius.
19. Europium forms a body-centered cubic unit cell and has a density of 4.68 g/cm3. From
this information, determine the length of the edge of the cubic cell.
20. Identify the kinds of IMF (London dispersion, dipole-dipole, or hydrogen bonding) that
are the most important in each of the following substances:
a. Methane, CH4
b. Methanol, CH3OH
c. Chloroform, CHCl3
d. Benzene, C6H6
e. Ammonia, NH3
f. Sulfur dioxide, SO2
21. Answer the following with increases or decreases.
a. If the IMF in a liquid increase, the normal boiling point and melting point of the
liquid _____________.
b. If the IMF in a liquid decrease, the vapor pressure of the liquid ____________.
c. If the IMF in a liquid decrease, the surface tension ___________.
d. If the temperature of a liquid increases, the equilibrium vapor pressure
___________.
22. If a machine does 4.8x103 kJ of work after an input of 7.31x104 kJ of heat, what is the
change in internal energy for the machine?
23. A metal radiator is made from 26.0 kg of iron. The specific heat of iron is 0.449 J/g°C.
How much heat must be supplied to the radiator to raise its temperature from 25.0 to
55.0°C?
24. A piece of titanium metal with a mass of 28.0 g is heated in boiling water to 99.5°C and
then dropped into a coffee cup calorimeter containing 75.0 g of water at 21.7°C. When
thermal equilibrium is reached, the final temperature is 24.3°C. Calculate the specific
heat capacity of titanium. (The specific heat of water is 4.18 J/g°C.)
25. When a 1.000 g sample of the rocket fuel hydrazine, N2H4, is burned in a bomb
calorimeter which contains 1200 g of water, the temperature rises from 24.62°C to
28.16°C. If the C for the bomb is 840 J/°C, calculate qrxn for combustion of a one-gram
sample.
26. How much heat must be supplied to change 100.0 g of water at 30.0 oC to steam at 110.0
o
C? The specific heats of water and steam are 4.18 J/g oC and 2.03 J/g oC, respectively.
The molar heat of vaporization of water is 40.7 kJ/mol.
27. Calculate the ΔH°rxn for: 2 H2O(l)  2 H2(g) + O2(g)
H2O(l)  H2O (g)
2 H2(g) + O2(g)  2 H2O(g)
ΔH° = 44.01 kJ
ΔH° = -483.64 kJ
28. Calculate the heat of combustion of diborane:
B2H6(g)
ΔH°f
36.0 kJ/mol
H2O(g)
B2O3(s)
B2H6(g) + 3 O2(g)  B2O3(s) + 3 H2O(g)
-241.8 kJ/mol
-1273.4 kJ/mol
29. Without doing a calculation, predict whether the entropy change will be positive or
negative when each of the following reactions occurs in the direction it is written.
a. CH3OH(l) + 3/2 O2(g)  CO2(g) + 2 H2O(g)
b. Na(s) + 1/2 F2(g)  NaF(s)
30. Calculate ΔG° at 45°C for the reaction for which
ΔH° = 293 kJ; ΔS° = -695 J/K
31. Estimate the temperature range over which the following reactions is spontaneous.
2 Al(s) + 3Cl2(g)  2 AlCl3(s)
ΔH° = -1408.4 kJ; ΔS° = -504.2 J/K
32. The following experimental data were obtained for the reaction of NH4+ and NO2- in acid
solution.
NH4+(aq) + NO2-(aq)  N2(aq) + 2 H2O(l)
[NH4+] (mol/L)
0.0092
0.0092
0.0488
0.0249
[NO2-] (mol/L)
0.098
0.049
0.196
0.196
Rate = Δ[N2]/ Δt (mol/L s)
3.33x10-7
1.66x10-7
3.51x10-6
1.80x10-6
Determine the rate law for this reaction, and calculate the rate constant.
33. The activation energy for the reaction in which CO2 decomposes to CO and a free radical
oxygen atom, O, has an activation energy of 460 kJ/mol. The frequency factor is 2x1011 s1
. What is the rate constant for this reaction at 298 K?
34. The following mechanism is proposed for a reaction:
NO + Br2  NOBr2
(slow)
NOBr2 + NO  2 NOBr
(fast)
a. Write the overall equation for the reaction.
b. What is the rate-determining step?
c. What is the intermediate in this reaction?
d. What is the molecularity of each step of the reaction?
e. Write the rate expression for each step.
35.
a. What is the rate law/expression for this reaction?
b. Determine the value of the rate constant k and the correct units.
c. What is the first half-life (t1/2) if the initial concentration of A, [A]o, is 0.30 M?
36. Write the equilibrium expression for the following reaction.
2 NOBr(g)
2 NO(g) + Br2(g)
37. Nitrosyl chloride, NOCl, decomposes to NO and Cl2 at high temperatures.
2 NOCl(g)
2 NO(g) + Cl2(g)
Suppose you place 2.00 mol NOCl in a 1.00 L flask and raise the temperature to 462°C.
When equilibrium has been established, 0.66 mol NO is present. Calculate the
equilibrium constant Kc for the decomposition reaction from this data.
38. The pH of a 0.25 M HCOOH formic acid solution is 2.17 at 25°C. Calculate the Ka for
the acid.
HCOOH(aq)
H+(aq) + HCOO-(aq)