2017
AP Chemistry
Free-Response Questions
reaction rate© 2017 The College Board. College Board, Advanced Placement Program, AP, AP Central, and the acorn logo are registered trademarks of the College Board. Visit the College Board on the Web: AP Central is the official online home for the AP Program:
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AP® CHEMISTRY EQUATIONS AND CONSTANTS Throughout the exam the following symbols have the definitions specified unless otherwise noted.
L, mL = liter(s), milliliter(s) mm Hg = millimeters of mercury
g = gram(s) J, kJ = joule(s), kilojoule(s)
nm =
nanometer(s) V = volt(s)
mole(s)
=
=
atmosphere(s)mol
atm
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2017 AP ® CHEMISTRY FREE-RESPONSE QUESTIONS
© 2017 The College Board.
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CHEMISTRY
Section II 7 Questions
Time—1 hour and 45 minutes
YOU MAY USE YOUR CALCULATOR FOR THIS SECTION.
Directions: Questions 1–3 are long free-response questions that require about 23 minutes each to answer and are worth 10 points each. Questions 4–7 are short free-response questions that require about 9 minutes each to answer and are worth 4 points each.
Write your response in the space provided following each question. Examples and equations may be included in your responses where appropriate. For calculations, clearly show the method used and the steps involved in arriving at your answers. You must show your work to receive credit for your answer. Pay attention to significant figures.
CS 2(g ) + 3 Cl 2(g )  →  CCl 4(g ) + S 2Cl 2(g )
1. Carbon tetrachloride, CCl 4(g ), can be synthesized according to the reaction represented above. A chemist runs
the reaction at a constant temperature of 120°C in a rigid 25.0 L container.
(a) Chlorine gas, Cl 2(g ), is initially present in the container at a pressure of 0.40 atm.
(i) How many moles of  Cl 2(g ) are in the container?
(ii) How many grams of carbon disulfide, CS 2(g ), are needed to react completely with the  Cl 2(g ) ? (b) At 30°C the reaction is thermodynamically favorable, but no reaction is observed to occur. However, at
120°C, the reaction occurs at an observable rate.
(i) Explain how the higher temperature affects the collisions between the reactant molecules so that the
reaction occurs at an observable rate at 120°C.  (ii) The graph below shows a distribution for the collision energies of reactant molecules at 120°C. Draw
a second curve on the graph that shows the distribution for the collision energies of reactant molecules  at 30°C.

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