12.1.3 Final Exam: Semester 2 Exam Test
Chemistry Name:
Points Possible:100
Date:
In this test, you will apply what you have learned in the semester. Answer the questions below.
Submit this to your teacher when you are done.
Show all your work on this test.
Question 1: Energy in Matter (20 points)
A. A cook decided to add salt to a pot of soup that was boiling on the stove. As soon as the
salt was added, the soup stopped boiling. Explain why this happened. (8 points)
● When adding the salt into the soup, it raised the boiling point of the water in the
soup. This phenomenon is well-acknowledged in Thermodynamics, and the
understanding that when you add a solute, one with a noticeably higher boiling
point than the solvent, to a solvent, being water in our explanation, the
temperature will increase to a point which the resulting solution will boil.
B. A pilot and a flight attendant get married and leave for their honeymoon on an airplane.
Well-meaning friends pack the plane with balloons. As the plane gains altitude, the balloons
begin to pop. (12 points)
i. Using the ideal gas law, explain why the balloons popped. (6 points)
● Using Boyle’s Gas law… In high altitudes, the air pressure is lower than the
pressure inside the balloon, so it will cause the balloon to expand beyond its own
capability to maintain it and inevitably pop.
ii. One balloon was only partly filled when put on the plane. During the flight, the balloon
volume increased from 7 L at 1.0 atm to 9 L. What was the cabin pressure on the airplane
during the flight? (Assume the balloon stretched very easily and the temperature was
constant.) (6 points)
● P = 0.7777(or 0.8 in 1 significant figure)
● Because the balloon is sealed, it would have a fixed number of moles and so the
volume must increase, as the pressure decreases.
Question 2: Equilibrium and Kinetics (20 points)
A. In certain conditions, the equilibrium concentrations for components in the reaction
2NOCl(g) 2NO(g) + Cl2(g) are [NO] = 0.02 M, [Cl2] = 0.01 M, and [NOCl] = 0.5 M. What is
the value of Keq, given Keq = ? (4 points)
● Keq = (products)/ (reactants)
● Keq = 9[NO]2 x [CI2]) / ([NOCI]2)
This study source was downloaded by 100000850872992 from CourseHero.com on 02-18-2023 20:51:19 GMT -06:00
https://www.coursehero.com/file/99067236/1213-Final-Exam-Semester-2-Exam-1pdf/
, ● Keq = ((0.02)2 x (0.01))/ (0.5)2
● Keq = 1.6 x 10-5
B. What is the pH of a weak acid solution that has an [H+] of 2.1 × 10–6 M? (4 points)
● pH = -log[H+]
● pH = -log(2.1E-6)
● pH = 5.6777
● pH = 5.68
C. Hydrogen sulfide, H2S, is a contaminant in natural gas. It can be removed by the reaction
CH4(g) + 2H2S(g) CS2(g) + 4H2(g). Heat is required to make the reaction occur. Use this
reaction to answer the following questions. (12 points)
i. What would happen to the equilibrium position if more CS2(g) were added? Would this
increase or decrease the amount of H2S? (4 points)
● If more CS2 is included to the equilibrium position, there would be an increase in
the amount of H2S.
ii. What would happen to the equilibrium position if the temperature were increased?
Explain your answer. (4 points)
● The equilibrium position would shift from left to right because an increase in
temperature favors an endothermic reaction. With that understanding, if the
temperature were to increase, more CS2 would be produced.
iii. What would happen to the equilibrium position if the pressure were increased? Explain
your answer. (4 points)
● The equilibrium would be unaffected because an increase in pressure would only
affect the equilibrium if the concentration is increased as well.
Question 3: Transferring Energy (20 points)
A. A student was given an unknown sample of a pure metal to identify. Its mass was 116 g.
He determined that 511 J of energy raised the temperature of the sample from 21.6°C to
40.5°C. Based on his measurements, what kind of metal was the sample? (4 points)
● Q = m c(Ts-T1) 511
● J - (116 g)(c)(40.5-21.6 C)
● c = 0.2333 J/gC
B. For the following questions, use the reaction NO2(g) N2(g) + O2(g), with ΔH = –33.1
kJ/mol and ΔS = 0.06302 kJ/(mol·K). (8 points)
i. Draw a possible potential energy diagram of the reaction. Label the enthalpy of the
reaction. (2 points)
This study source was downloaded by 100000850872992 from CourseHero.com on 02-18-2023 20:51:19 GMT -06:00
https://www.coursehero.com/file/99067236/1213-Final-Exam-Semester-2-Exam-1pdf/
Chemistry Name:
Points Possible:100
Date:
In this test, you will apply what you have learned in the semester. Answer the questions below.
Submit this to your teacher when you are done.
Show all your work on this test.
Question 1: Energy in Matter (20 points)
A. A cook decided to add salt to a pot of soup that was boiling on the stove. As soon as the
salt was added, the soup stopped boiling. Explain why this happened. (8 points)
● When adding the salt into the soup, it raised the boiling point of the water in the
soup. This phenomenon is well-acknowledged in Thermodynamics, and the
understanding that when you add a solute, one with a noticeably higher boiling
point than the solvent, to a solvent, being water in our explanation, the
temperature will increase to a point which the resulting solution will boil.
B. A pilot and a flight attendant get married and leave for their honeymoon on an airplane.
Well-meaning friends pack the plane with balloons. As the plane gains altitude, the balloons
begin to pop. (12 points)
i. Using the ideal gas law, explain why the balloons popped. (6 points)
● Using Boyle’s Gas law… In high altitudes, the air pressure is lower than the
pressure inside the balloon, so it will cause the balloon to expand beyond its own
capability to maintain it and inevitably pop.
ii. One balloon was only partly filled when put on the plane. During the flight, the balloon
volume increased from 7 L at 1.0 atm to 9 L. What was the cabin pressure on the airplane
during the flight? (Assume the balloon stretched very easily and the temperature was
constant.) (6 points)
● P = 0.7777(or 0.8 in 1 significant figure)
● Because the balloon is sealed, it would have a fixed number of moles and so the
volume must increase, as the pressure decreases.
Question 2: Equilibrium and Kinetics (20 points)
A. In certain conditions, the equilibrium concentrations for components in the reaction
2NOCl(g) 2NO(g) + Cl2(g) are [NO] = 0.02 M, [Cl2] = 0.01 M, and [NOCl] = 0.5 M. What is
the value of Keq, given Keq = ? (4 points)
● Keq = (products)/ (reactants)
● Keq = 9[NO]2 x [CI2]) / ([NOCI]2)
This study source was downloaded by 100000850872992 from CourseHero.com on 02-18-2023 20:51:19 GMT -06:00
https://www.coursehero.com/file/99067236/1213-Final-Exam-Semester-2-Exam-1pdf/
, ● Keq = ((0.02)2 x (0.01))/ (0.5)2
● Keq = 1.6 x 10-5
B. What is the pH of a weak acid solution that has an [H+] of 2.1 × 10–6 M? (4 points)
● pH = -log[H+]
● pH = -log(2.1E-6)
● pH = 5.6777
● pH = 5.68
C. Hydrogen sulfide, H2S, is a contaminant in natural gas. It can be removed by the reaction
CH4(g) + 2H2S(g) CS2(g) + 4H2(g). Heat is required to make the reaction occur. Use this
reaction to answer the following questions. (12 points)
i. What would happen to the equilibrium position if more CS2(g) were added? Would this
increase or decrease the amount of H2S? (4 points)
● If more CS2 is included to the equilibrium position, there would be an increase in
the amount of H2S.
ii. What would happen to the equilibrium position if the temperature were increased?
Explain your answer. (4 points)
● The equilibrium position would shift from left to right because an increase in
temperature favors an endothermic reaction. With that understanding, if the
temperature were to increase, more CS2 would be produced.
iii. What would happen to the equilibrium position if the pressure were increased? Explain
your answer. (4 points)
● The equilibrium would be unaffected because an increase in pressure would only
affect the equilibrium if the concentration is increased as well.
Question 3: Transferring Energy (20 points)
A. A student was given an unknown sample of a pure metal to identify. Its mass was 116 g.
He determined that 511 J of energy raised the temperature of the sample from 21.6°C to
40.5°C. Based on his measurements, what kind of metal was the sample? (4 points)
● Q = m c(Ts-T1) 511
● J - (116 g)(c)(40.5-21.6 C)
● c = 0.2333 J/gC
B. For the following questions, use the reaction NO2(g) N2(g) + O2(g), with ΔH = –33.1
kJ/mol and ΔS = 0.06302 kJ/(mol·K). (8 points)
i. Draw a possible potential energy diagram of the reaction. Label the enthalpy of the
reaction. (2 points)
This study source was downloaded by 100000850872992 from CourseHero.com on 02-18-2023 20:51:19 GMT -06:00
https://www.coursehero.com/file/99067236/1213-Final-Exam-Semester-2-Exam-1pdf/
