12/18/2013
Directions
• You will have 4 minutes to answer each question.
• The scoring will be 16 points for a correct response in
the 1st minute, 12 points for a correct response in the 2nd
minute, 8 points for a correct response in the 3rd minute,
4 points for a correct response in the 4th minute. A
sliding scale will be used.
• Once your hand has been raised with the answer sheet,
it must stay up. If you put your hand down, your
answer will be disqualified for that question.
• Your answer must be submitted on the official answer
sheet that has been correctly filled out. Otherwise your
answer will be disqualified.
• Your answer must be in the specific form that the
question asks for.
1
12/18/2013
Directions……
• If not otherwise noted, the answers should be in one of the
following generally accepted forms:
– Denominators rationalized
– Simplest radical form
– Fractions, improper fractions, or mixed numbers in
simplest form
– Equations should have integral coefficients in standard
form
• No units are necessary
• Report answers with correct significant figures (Chemistry)
• Calculators are not allowed in any division except Statistics
& Chemistry (non-programmable only).
• Headphones, beepers, cell phones, or electronic devices are
not permitted.
• Sunglasses and hats are not to be worn during the
competition.
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1) The diagram below is the Born-Haber cycle for the
formation of crystalline potassium fluoride.
Which energy change on the diagram corresponds
to the electron affinity of fluorine?
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2) After the following chemical equation is
balanced, what is the coefficient of H2O?
__Al2S3 + __H2O  __Al(OH)3 + __H2S
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3) Which is the shortest bond in the following
molecule ?
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4) What is the approximate bond angle for
O-C-O in the CO32- ion?
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5) A 0.750 g sample of an unknown
nonelectrolyte is dissolved in 20.0 g of
benzene; the freezing point of the solution
is 4.53oC. Calculate the molar mass of the
substance.
The normal freezing point for benzene is 5.53oC
and the Kf is 5.12 oC/m.
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6) How many mL of a 0.733 M solution of Sr(OH)2
are required to neutralize 23.7 mL of a 0.964 M
HClO4 solution?
__Sr(OH)2 (aq) + __ HClO4 (aq) __Sr(ClO4)2 (aq) + __H2O (l)
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7) The reaction of A  B is second order in terms
of [A] and the rate constant is 0.039 M-1s-1.
After 23 seconds the concentration of [A] is
0.30 M. What was the initial concentration?
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8) Elemental analysis shows a 5.000 g sample of
caprinitrile contains 3.918 g C, 0.6248 g H,
and 0.4571 g N. What is the empirical
formula of caprinitrile?
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9) Iron will rust in the presence of air. Balance
the rust formation reaction below. What are
the coefficients for Fe and H+?
Fe (s) + H+(aq) + O2 (g)  Fe2+ (aq) + H2O (l)
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10) What is the pH of a solution prepared by
dissolving 0.025 mol of Ba(OH)2 in water to
give 455 mL of solution?
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11) Calculate ΔH (in kJ) for
P4 (s) + 10 Cl2 (g)  4 PCl5 (g)
Given the following reactions:
P4 (s) + 6 Cl2 (g)  4 PCl3 (g)
ΔH = - 1148 kJ
PCl5 (g)  PCl3 (g) + Cl2 (g)
ΔH =
115 kJ
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12) The reaction A + B  C is 1st order in A and
1st order in B. The rate constant k = 2.7X10-4
M-1s-1. What is the rate when [A] = 0.010 M
and [B] = 0.10 M?
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13) A 35.0 mL sample of 0.150 M aqueous acetic acid
(CH3COOH) is titrated with 0.150 M NaOH. Ka for acetic
acid = 1.8 x 10-5. Calculate the pH after 30.0 mL of the
NaOH is added.
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14) What is the common name for the following
structure?
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15) The reaction
2ClO2(aq) + 2OH-(aq)  ClO3-(aq) + ClO2-(aq) + H2O(aq)
was studied with the following results:
Experiment
1
2
3
Calculate
the
[ClO2] (M)
[OH-] (M)
Initial Rate (M/s)
0.060
0.030
0.020
0.030
0.020 rate when
0.090 [ClO ]
initial
2
0.02484
0.00276
=0.00828
0.080 M and
[OH-] = 0.150 M.
Answers
1) 4
8) C10H19N
2) 6
9) 2 Fe , 4 H+
3) 5
10) 13.04
4) 120°
11) -1608
5) 192
12) 2.7 × 10-7 M s -1
6) 15.6
13) 5.52
7) 0.41
14) isobutane
15) 0.22
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