CHEM 1413.001 - Exam 3 – November 2, 2016 - Version A
KClO3 - 122.6 SO2 - 64.1
Cl2 - 71.
CO2 - 44.
C2H6 - 30.
NH3 - 17.
H2O - 18.
C6H14 - 86.
Na - 23.
AgNO3 - 169.9 C10H8 - 128.
Molar Masses: Mn - 54.9
Conversions:
1 atm = 760 torr
1 L = 1.06 Qt
1 L•atm = 101 J
Constants:
NA = 6.02x1023 mol-1
R = 0.082 L•atm/mol•K
R = 8.31 J/mol•K
CHEM 1413.001 - Exam 3 – November 2, 2016 - Version A
Name______________________________
(76)
MULTIPLE CHOICE (Circle the ONE correct answer)
1. How many molecules are there in a sample of a gas at 1000 torr and 250 oC in a
20 L container?
(A) 2.8x1022
(B) 3.7x1023
(C) 7.7x1023
(D) 2.8x1023
2. The temperature of a gas at a pressure of 400 torr and volume of 40 L is 200 oC.
What is the temperature of the gas, in oC, at a pressure of 500 torr and volume of
30 L?
(A) 170 oC
(B) 188 oC
(C) 124 oC
(D) 82 oC
3. An unknown gas has a density of 2.80 g/L at a temperature of 25 oC and
pressure of 0.80 atm. What is the approximate Molar Mass of the gas?
(A) 39 g/mol
(B) 114 g/mol
(C) 62 g/mol
(D) 86 g/mol
4. The fraction of Xe(g) in air is 450 ppb (parts per billion). What is the partial
pressure of Xe(g), in torr, when the total air pressure of 0.90 atm.?
(A) 4.1x10-7 torr
(B) 3.1x10-4 torr
(C) 2.7x10-1 torr
(D) 3.1x10-1 torr
5. A mixture contains 0.40 moles of N2(g) and 1.20 moles of O2(g). The partial
pressure of N2 is 150 torr. Therefore, the partial pressure of O2 is ____torr and
the total pressure is ____torr.
(A) 450, 600
(B) 600, 750
(C) 600, 450
(D) 300, 450
6. Dimanganese decacarbonyl, Mn2(CO)10(s), can be made by the reaction of Mn(s)
with CO(g). Approximately how many grams of Mn(s) are required to react
completely 1200 L of CO(g) at 100 oC and a pressure of 500 torr to produce
Mn2(CO)10(s)?
(A) 140 g
(B) 280 g
(C) 1420 g
(D) None of the above
7. Consider the reaction, __N2(g) + __O2(g) → __N2O5(g). Approximately how
many moles of N2O5 can be produced by the reaction of 60 L of N2(g) at 400 K
and 1. atm. with 130 L of O2(g) at 400 K and 1. atm?
(A) 1.83 mol
(B) 3.96 mol
(C) 1.32 mol
(D) 1.58 mol
Version A
8. When heat is applied to potassium chlorate, KClO3(s), it decomposes to
potassium chloride, KCl(s), and oxygen, O2(g). When a sample of KClO3 is
heated to 250 oC, it decomposes to produce 460 L of O2(g) at 250 oC and
0.90 atm. Approximately how many grams of KClO3(s) decomposed?
(A) 790 g
(B) 1180 g
(C) 1650 g
(D) 1780 g
9. The RMS average speed of SO2(g) molecules at 25 oC is 340 m/s. What is the
RMS average speed of SO2(g) molecules at 800 oC?
(A) 1920 m/s
(B) 180 m/s
(C) 1220 m/s
(D) 645 m/s
10. Consider the following 3 gases: (i) Cl2(g) at 150 oC, (ii) CO2(g) at 180 oC,
(iii) C2H6(g) at 150 oC. _____ has the lowest rate of effusion and ____ has the
highest Kinetic Energy.
(A) CO2 , Cl2
(B) Cl2 , CO2
(C) C2H6 , CO2
(D) Cl2 , C2H6
11. It takes 45 seconds for a sample of SO2(g) to effuse through a pinhole. Under
the same conditions it takes 60 seconds for an equivalent sample of an unknown
gas to effuse through the pinhole. Therefore, the Molar Mass of the unknown
gas is:
(A) 85 g/mol
(B) 74 g/mol
(C) 114 g/mol
(D) 36 g/mol
12. The compressibility of a gas, PV/RT, represents the deviation from Ideal Gas
behavior. If the compressibility is greater than 1, i.e. PV/RT > 1, then:
(i)
(ii)
(iii)
(iv)
Attractive Forces predominate
Repulsive Forces predominate
The gas is less compressibile than an Ideal Gas
The gas is more compressibile than an Ideal Gas
(A) i & iv
(B) ii & iii
(C) i & iii
(D) ii & iv
13. For which of the following processes is the work positive (w>0)?
(i)
(ii)
(iii)
(iv)
A gas is cooled at constant pressure
C6H6(l) → C6H6(g)
A gas is cooled at constant volume
N2(g) + 3 H2(g) → 2 NH3(g)
(A) i & iv
(B) i & ii
(C) i & iii & iv
(D) iv only
14. The constant pressure molar heat capacity of NH3(g) is 37. J/mol-oC. When 8. kJ
of heat is added (at constant pressure) to a sample of 40 g of NH3(g) originally at
30 oC, what is the final temperature of the sample?
(A) 104 oC
(B) 92 oC
(C) 163 oC
(D) 122 oC
Version A
15. When a sample of a gas is cooled from 300 oC to 100 oC at a constant pressure
of 2,000 torr, the volume changes from 120 Qt. to 75 Qt.. What is the
approximate value of the work (w) for this process (in kJ)?
(A) -12.7 kJ
(B) +11.3 kJ
(C) +12.7 kJ
(D) +0.11 kJ
For #16 - #17: Consider the following reaction:
2 C6H14(l) + 19 O2(g) → 12 CO2(g) + 14 H2O(l)
∆H = -8320 kJ
16. If C6H14 reacts with O2, and 12,000. kJ of heat is released, approximately how
many grams of H2O(l) have been produced?
(A) 360 g
(B) 175 g
(C) 470 g
(D) 26 g
17. What is the approximate heat involved in the production of 40 g of C6H14(l) from
CO2(g) and H2O(l)?
(A) +1930 kJ
(B) +3870 kJ
(C) -1930 kJ
(D) -3870 kJ
18. Consider the reaction of sodium with water:
2 Na(s) + 2 H2O(l) → 2 NaOH(aq) + H2(g)
∆Ho = -240 kJ
The Enthalpy of Fusion of water is 6.0 kJ/mol. When 40 grams of Na(s) is
dropped in a container containing ice and liquid water at 0 oC, approximately how
many grams of ice will melt?
(A) 830 g
(B) 630 g
(C) 1250 g
(D) 470 g
19. In an experiment to determine the Enthalpy of Solution of AgNO3, 20. grams of
AgNO3(s) was dissolved in 100 grams of water at 28.0 oC. It was found that the
temperature in the solution cooled to 21.7 oC. The Heat Capacity of the solution
was Csoln = 420 J/oC.
Therefore, the Heat of Solution of AgNO3 is approximately:
(A) -13.2 kJ
(B) +13.2 kJ
(C) +22.5 kJ
(D) None of the above
-----------------------------------------------------------------------------------------------------------------Two (2) Problems Follow (You MUST show your work to receive credit)
Version A
(12) 1.
A hypothetical element, X(s) , reacts with O2(g) to form X3O4(s). It is found
that 20. grams of X require 8.10 L of O2 at 30 oC and 700. torr to react completely.
Calculate the Molar Mass of the element, X?
(12) 2.
Use the data below on a 320 gram sample of Napthalene, C10H8, to calculate the
heat involved, in kiloJoules (kJ) for the process below:
C10H8(gas, 218 oC) → C10H8(solid, 80 oC) at a constant pressure of 1 atm.
C5H8 Data
M = 128. g/mol
Tm = 80 oC
Tb = 218 oC
∆Hfus= 19. kJ/mol
∆Hvap = 55. kJ/mol
Cp,m(liq) = 196 J/mol-oC
CHEM 1413.001 - Exam 3 – November 2, 2016 - Version B
KClO3 - 122.6 SO2 - 64.1
Cl2 - 71.
CO2 - 44.
C2H6 - 30.
NH3 - 17.
H2O - 18.
C6H14 - 86.
Na - 23.
AgNO3 - 169.9 C10H8 - 128.
Molar Masses: Mn - 54.9
Conversions:
1 atm = 760 torr
1 L = 1.06 Qt
1 L•atm = 101 J
Constants:
NA = 6.02x1023 mol-1
R = 0.082 L•atm/mol•K
R = 8.31 J/mol•K
CHEM 1413.001 - Exam 3 – November 2, 2016 - Version B
Name______________________________
(76)
MULTIPLE CHOICE (Circle the ONE correct answer)
1. The temperature of a gas at a pressure of 400 torr and volume of 40 L is 200 oC.
What is the temperature of the gas, in oC, at a pressure of 500 torr and volume of
30 L?
(A) 124 oC
(B) 188 oC
(C) 170 oC
(D) 82 oC
2. How many molecules are there in a sample of a gas at 1000 torr and 250 oC in a
20 L container?
(A) 2.8x1022
(B) 7.7x1023
(C) 2.8x1023
(D) 3.7x1023
3. The fraction of Xe(g) in air is 450 ppb (parts per billion). What is the partial
pressure of Xe(g), in torr, when the total air pressure of 0.90 atm.?
(A) 3.1x10-4 torr
(B) 4.1x10-7 torr
(C) 2.7x10-1 torr
(D) 3.1x10-1 torr
4. A mixture contains 0.40 moles of N2(g) and 1.20 moles of O2(g). The partial
pressure of N2 is 150 torr. Therefore, the partial pressure of O2 is ____torr and
the total pressure is ____torr.
(A) 600, 450
(B) 600, 750
(C) 450, 600
(D) 300, 450
5. An unknown gas has a density of 2.80 g/L at a temperature of 25 oC and
pressure of 0.80 atm. What is the approximate Molar Mass of the gas?
(A) 39 g/mol
(B) 86 g/mol
(C) 62 g/mol
(D) 114 g/mol
6. Consider the reaction, __N2(g) + __O2(g) → __N2O5(g). Approximately how
many moles of N2O5 can be produced by the reaction of 60 L of N2(g) at 400 K
and 1. atm. with 130 L of O2(g) at 400 K and 1. atm?
(A) 1.83 mol
(B) 3.96 mol
(C) 1.58 mol
(D) 1.32 mol
7. Dimanganese decacarbonyl, Mn2(CO)10(s), can be made by the reaction of Mn(s)
with CO(g). Approximately how many grams of Mn(s) are required to react
completely 1200 L of CO(g) at 100 oC and a pressure of 500 torr to produce
Mn2(CO)10(s)?
(A) 280 g
(D) None of the above
(B) 140 g
(C) 1420 g
Version B
8. The RMS average speed of SO2(g) molecules at 25 oC is 340 m/s. What is the
RMS average speed of SO2(g) molecules at 800 oC?
(A) 1920 m/s
(B) 645 m/s
(C) 1220 m/s
(D) 180 m/s
9. When heat is applied to potassium chlorate, KClO3(s), it decomposes to
potassium chloride, KCl(s), and oxygen, O2(g). When a sample of KClO3 is
heated to 250 oC, it decomposes to produce 460 L of O2(g) at 250 oC and
0.90 atm. Approximately how many grams of KClO3(s) decomposed?
(A) 1780 g
(B) 1180 g
(C) 1650 g
(D) 790 g
10. It takes 45 seconds for a sample of SO2(g) to effuse through a pinhole. Under
the same conditions it takes 60 seconds for an equivalent sample of an unknown
gas to effuse through the pinhole. Therefore, the Molar Mass of the unknown
gas is:
(A) 85 g/mol
(B) 114 g/mol
(C) 74 g/mol
(D) 36 g/mol
11. Consider the following 3 gases: (i) Cl2(g) at 150 oC, (ii) CO2(g) at 180 oC,
(iii) C2H6(g) at 150 oC. _____ has the lowest rate of effusion and ____ has the
highest Kinetic Energy.
(A) Cl2 , CO2
(B) CO2 , Cl2
(C) C2H6 , CO2
(D) Cl2 , C2H6
12. The compressibility of a gas, PV/RT, represents the deviation from Ideal Gas
behavior. If the compressibility is greater than 1, i.e. PV/RT > 1, then:
(i)
(ii)
(iii)
(iv)
Attractive Forces predominate
Repulsive Forces predominate
The gas is less compressibile than an Ideal Gas
The gas is more compressibile than an Ideal Gas
(A) i & iv
(B) ii & iv
(C) i & iii
(D) ii & iii
13. The constant pressure molar heat capacity of NH3(g) is 37. J/mol-oC. When 8. kJ
of heat is added (at constant pressure) to a sample of 40 g of NH3(g) originally at
30 oC, what is the final temperature of the sample?
(A) 104 oC
(B) 92 oC
(C) 122 oC
(D) 163 oC
14. For which of the following processes is the work positive (w>0)?
(i)
(ii)
(iii)
(iv)
A gas is cooled at constant pressure
C6H6(l) → C6H6(g)
A gas is cooled at constant volume
N2(g) + 3 H2(g) → 2 NH3(g)
(A) i & ii
(B) i & iv
(C) i & iii & iv
(D) iv only
Version B
For #15 - #16: Consider the following reaction:
2 C6H14(l) + 19 O2(g) → 12 CO2(g) + 14 H2O(l)
∆H = -8320 kJ
15. If C6H14 reacts with O2, and 12,000. kJ of heat is released, approximately how
many grams of H2O(l) have been produced?
(A) 360 g
(B) 26 g
(C) 470 g
(D) 175 g
16. What is the approximate heat involved in the production of 40 g of C6H14(l) from
CO2(g) and H2O(l)?
(A) -1930 kJ
(B) +3870 kJ
(C) +1930 kJ
(D) -3870 kJ
17. When a sample of a gas is cooled from 300 oC to 100 oC at a constant pressure
of 2,000 torr, the volume changes from 120 Qt. to 75 Qt.. What is the
approximate value of the work (w) for this process (in kJ)?
(A) -12.7 kJ
(B) +12.7 kJ
(C) +11.3 kJ
(D) +0.11 kJ
18. In an experiment to determine the Enthalpy of Solution of AgNO3, 20. grams of
AgNO3(s) was dissolved in 100 grams of water at 28.0 oC. It was found that the
temperature in the solution cooled to 21.7 oC. The Heat Capacity of the solution
was Csoln = 420 J/oC.
Therefore, the Heat of Solution of AgNO3 is approximately:
(A) -13.2 kJ
(B) +22.5 kJ
(C) +13.2 kJ
(D) None of the above
19. Consider the reaction of sodium with water:
2 Na(s) + 2 H2O(l) → 2 NaOH(aq) + H2(g)
∆Ho = -240 kJ
The Enthalpy of Fusion of water is 6.0 kJ/mol. When 40 grams of Na(s) is
dropped in a container containing ice and liquid water at 0 oC, approximately how
many grams of ice will melt?
(A) 830 g
(B) 470 g
(C) 1250 g
(D) 630 g
-----------------------------------------------------------------------------------------------------------------Two (2) Problems Follow (You MUST show your work to receive credit)
Version B
(12) 1.
A hypothetical element, X(s) , reacts with O2(g) to form X3O4(s). It is found
that 20. grams of X require 7.60 L of O2 at 30 oC and 700. torr to react completely.
Calculate the Molar Mass of the element, X?
(12) 2.
Use the data below on a 384. gram sample of Napthalene, C10H8, to calculate the
heat involved, in kiloJoules (kJ) for the process below:
C10H8(gas, 218 oC) → C10H8(solid, 80 oC) at a constant pressure of 1 atm.
C5H8 Data
M = 128. g/mol
Tm = 80 oC
Tb = 218 oC
∆Hfus= 19. kJ/mol
∆Hvap = 55. kJ/mol
Cp,m(liq) = 196 J/mol-oC