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1) The pH of a 0.15 M aqueous solution of NaZ (the sodium salt of HZ) is 10.7. What is
the Ka for HZ?
A) 1.6 x 10-6
B) 6.0 x 10-9
C) 8.9 x 10-4
D) 1.3 x 10-12
E) 3.3 x 10-8
2) Elements in Group 6A are known as the ________.
A) alkali metals
B) chalcogens
C) alkaline earth metals
D) halogens
E) noble gases
3) The reaction of potassium metal with elemental hydrogen produces ________.
A) KH
B) KH2
C) K2H
D) None of the above; potassium will not react directly with hydrogen.
E) KOH
4) At appro x imately what number of protons, or neutrons, does the 1:1 ratio of protons
to neutrons start to produce unstable nuclei?
A) 10
B) 20
C) 30
D) 50
E) 80
5) For which one of the following equations is ΔH°rxn equal to H°f for the product?
A) Xe (g) + 2F2 (g) → XeF4 (g)
B) CH4 (g) + 2Cl2 (g) → CH2Cl2 (l) + 2HCl (g)
C) N2 (g) + O3 (g) → N2O3 (g)
D) 2CO (g) + O2 (g) → 2CO2 (g)
E) C (diamond) + O2 (g) → CO2 (g)
6) Lithium and nitrogen react to produce lithium nitride:
6Li (s) + N2 (g) → 2Li3N (s)
How many moles of N2 are needed to react with 0.550 mol of lithium?
A) 3.30
B) 0.550
C) 0.183
D) 1.65
E) 0.0917
7) Thermodynamic Quantities for Selected Substances at 298.15 K (25 oC)
The value of H o for the decomposition of POCl3 into its constituent elements,
2POCl3 (g) --> P2 (g) + O2 (g) + 3Cl2 (g)
is ________ kJ/mol.
A) -1228.7
B) +1228.7
C) -940.1
D) +940.1
E) 0.00
8) Consider the following reaction at equilibrium:
2NH3 (g) N2 (g) + 3H2 (g)
Le Ch¢telier's principle predicts that the moles of H2 in the reaction container will
increase with ________.
A) some removal of NH3 from the reaction vessel (V and T constant)
B) a decrease in the total pressure (T constant)
C) addition of some N2 to the reaction vessel (V and T constant)
D) a decrease in the total volume of the reaction vessel (T constant)
E) an increase in total pressure by the addition of helium gas (V and T constant)
9) A reaction vessel is charged with hydrogen iodide, which partially decomposes to
molecular hydrogen and iodine:
2HI (g) H2(g) + I2(g)
When the system comes to equilibrium at 425 oC, PHI = 0.708 atm, and PH2 = PI2 =
0.0960 atm. The value of Kp at this temperature is ________.
A) 6.80 x 10-2
B) 1.30 x 10-2
C) 54.3
D) 1.84 x 10-2
E) Kp cannot be calculated for this gas reaction when the volume of the reaction vessel
is not given.
10) Phosphorous and chlorine gases combine to produce phosphorous trichloride:
P2 (g) + 3Cl2 (g) --> 2PCl3 (g)
G o at 298 K for this reaction is -642.9 kJ/mol. The value of G at 298 K for a
reaction mixture that consists of 1.9 atm P2, 1.6 atm Cl2, and 0.65 atm PCl3 is
________.
A) -34.9
B) -4.46 x 103
C) -7.86 x 103
D) -714.1
E) -650.1
11) What is the most common geometry found in four-coordinate complexes?
A) square planar
B) octahedral
C) tetrahedral
D) icosahedral
E) trigonal bipyramidal
12) Given the data in the table below, ΔH°rxn for the reaction
PCl3 (g) + 3 HCl (g) → 3Cl2 (g) + PH3 (g)
is ________ kJ.
A) -570.37
B) -385.77
C) 570.37
D) 385.77
E) The ΔH°f of Cl2 (g) is needed for the calculation.
13) Ozone is a a(n) ________ of oxygen.
A) isotope
B) allotrope
C) precursor
D) peroxide
E) free radical
14) Thermodynamic Quantities for Selected Substances at 298.15 K (25 oC)
The value of G o at 25 oC for the decomposition of POCl3 into its constituent
elements,
2POCl3 (g) --> P2 (g) + O2 (g) + 3Cl2 (g)
is ________ kJ/mol.
A) -1108.7
B) +1108.7
C) -606.2
D) +606.2
E) -1,005
15) There are ________ significant figures in the answer to the following computation:
A) 1
B) 2
C) 3
D) 4
E) 5
16) Why are chlorofluorocarbons so damaging to the ozone layer when they are such
stable molecules?
A) They contain a double bond that ozone readily attacks, resulting in the destruction of
the ozone.
B) They are very light molecules that rapidly diffuse into the upper atmosphere and
block the radiation that causes formation of ozone.
C) They are greenhouse gases that raise the temperature above the dissociation
temperature of ozone.
D) The radiation in the stratosphere dissociates them producing chlorine atoms that
catalytically destroy ozone.
E) CFCs do not damage the ozone.
17) The formula of the chromate ion is ________.
A) CrO4
2-
B) CrO2
3-
C) CrO-
D) CrO3
2-
E) CrO2-
18) The pressure of a sample of CH4 gas (6.022 g) in a 30.0 L vessel at 402 K is
________ atm.
A) 2.42
B) 6.62
C) 0.413
D) 12.4
E) 22.4
19) How many milliliters of 0.188 M HClO4 solution are needed to neutralize 50.00 mL
of 0.0832 M NaOH?
A) 0.782
B) 8.85 x 10-3
C) 113
D) 0.0452
E) 22.1
20) Arrange the following gases in order of increasing average molecular speed at 25
°C.
He, O2, CO2, N2
A) He < N2 < O2 < CO2
B) He < O2 < N2 < CO2
C) CO2 < O2 < N2 < He
D) CO2 < N2 < O2 < He
E) CO2 < He < N2 < O2
