Solutions to the 2017 Competition

Individual Round

Please note:

Question 2b) Two answers will be accepted for this problem. The current posted answer will be accepted. Additionaly, students who circled nitrogen as sp2 hybridized will also receive credit, due to a resonance form of the molecule.

Question 5c) This question has been eliminated because equilibrium conditions were not specified in the problem, making the given solution incorrect.

Chemistry of Coffee

Please note:

Question 2b) The posted solution uses an incorrect temperature of 273.15 K, however, the problem states that the temperature should be 298 K. The graders will use the correct value of 298 K. Appeals specific to this do not need to be submitted.

Chemistry of Industry

Please note:

Question 4b) The posted solution states that the reduction potential is (-0.771 - 1.33), however, the correct reduction potential should be (-0.771 + 1.33). Thus, the reduction potential is positive. Therefore, delta(G) will be negative, and the reaction will be favorable. The graders will use this correct answer in grading the exams. Appeals specific to this do not need to be submitted.

Question 4d) The posted solution has an incorrect form of the Nernst equation because its forgets to divide by the number of moles of electrons. The corrected form of the equation will be used in grading.

Chemistry of Life

Team Round

Please note:

Question 1a) The correct answer is +97 rather than -97.

Question 1a.v) Since teams were informed to use information from part a, and the first part incorrectly flipped sodium and potassium intercellular concentrations, answers that stated that potassium depolarized the membrane while sodium repolarized are accepted if they invoke the incorrect conch gradients given in a.

Question 1iv.c) The correct answer is 92.7 ms.