Practice Exam 3 - Fall 2024 (PDF)

DISCLAIMER! This “Practice Exam” is not intended to be comprehensive of every single topic or every single type of question you could see. (To see a complete list of all learning objectives covered on this Exam, see the “Learning Objectives for Each Exam” document on Moodle.) This “Practice Exam” is...

DISCLAIMER! This “Practice Exam” is not intended to be comprehensive of every single topic or every single type of question you could see. (To see a complete list of all learning objectives covered on this Exam, see the “Learning Objectives for Each Exam” document on Moodle.) This “Practice Exam” is simply intended to give you additional examples in a multiple-choice style format. To use this “Practice Exam” most effectively, I would recommend completing it by yourself without notes with a 50-minute timer (although you will have 75 minutes for our graded exams, the number of questions here is more relevant for a 50 minute time block). Directions – Multiple Choice. Unless otherwise stated, each multiple-choice question will have only one correct answer. 1. Choose which answer correctly sets up the math to solve for ΔH for the below reaction: CO2 + 2Cl2 → CCl4 + O2 a. ΔH = [(2 x 358) + (2 x 243)] - [(4 x 328) + (146)] b. ΔH = [(2 x 358) + (2 x 243)] - [(4 x 328) + (2 x 146)] c. ΔH = [(799) + (243)] - [(4 x 328) + (495)] d. ΔH = [(2 x 799) + (4 x 243)] - [(4 x 328) + (2 x 146)] e. ΔH = [(2 x 799) + (2 x 243)] - [(4 x 328) + (495)] 2. Which of the following reactions would you predict to be spontaneous at all temperatures? a. 2NO2 (g) → N2O4 (g) ΔH = -58 kJ b. OF2 (g) + H2O (g) → O2 (g) + 2HF (g) ΔH = -79 kJ c. CH3OH (g) → H2CO (g) + H2 (g) ΔH = +86 kJ d. 8H2O (g) + 6CO2 (g) → 2C3H8 (g) + 10 O2 (g) ΔH = +521 kJ 3. Choose which of the following statements correctly describes the below reaction: CO2 (g) + 2H2O (l) → CH4 (g) + 2O2 (g) ΔH = +891 kJ a. The reaction is both enthalpically favorable and entropically favorable b. The reaction is enthalpically favorable, but entropically unfavorable c. The reaction is enthalpically unfavorable, but entropically favorable d. The reaction is both enthalpically unfavorable and entropically unfavorable 4. You observe a spontaneous reaction taking place in a flask. When you touch the flask, it feels warm and gets warmer as the reaction progresses. You also notice the formation of gas bubbles, which intensifies as the reaction progresses. Choose the statement that most accurately describes the process. a. The reaction is endothermic and increasing in entropy b. The reaction is endothermic and decreasing in entropy c. The reaction is exothermic and increasing in entropy d. The reaction is exothermic and decreasing in entropy 5. In which of the following reaction coordinate diagrams does the reverse reaction take place at the fastest rate? 6. The below reaction is exothermic in the forward direction. Consider Le Chatelier’s principle to determine which actions would ultimately cause equilibrium to shift to the left as much as possible, thereby increasing the concentration of reactants and decreasing the concentration of products? CH4 (g) + 2O2 (g) ⇌ CO2 (g) + H2O (g) a. decrease the temperature and add O2 b. decrease the temperature and remove O2 c. increase the temperature and remove O2 d. increase the temperature and add O2 Use the reaction coordinate diagram shown below for the next 3 questions 7. Choose the answer which accurately describes the forward reaction depicted by the above reaction coordinate diagram. a. The reactants are favored because they are lower in energy b. The reactants are favored because they are higher in energy c. The products are favored because they are lower in energy d. The products are favored because they are higher in energy 8. Choose the answer which accurately describes the forward reaction depicted by the above reaction coordinate diagram. a. ΔG = -20 kJ b. ΔG = -30 kJ c. ΔG = +20 kJ d. ΔG = +30 kJ e. ΔG = +60 kJ 9. Choose the descriptions which accurately portray the forward reaction depicted by the above reaction coordinate diagram. a. Extensive; Keq >> 1 b. Not extensive; Keq >> 1 c. Extensive; Keq