Question 1

Thermodynamics is the study of systems on the microscopic scale. It explains the interrelation of energy and chemistry and relies on information about individual molecular properties to do this.

Accepted Answer

A) True 
 B)False

Question 2

The standard enthalpy change of fusion and vaporization for water are +6.01 kJ mol-1 and +40.7 kJ mol-1 respectively. Why is the value for vaporization so much larger than fusion?

Accepted Answer

A)   Because it is measured at a higher temperature.
B)   Because the pressure has increased.
C)   Because gas is released into the surroundings.
D)   Because overcoming all intermolecular forces that hold a liquid together needs a lot of energy.E) All of the above
F) None of the above

Question 3

For a reaction conducted at constant pressure and at 298 K the change in number of moles of gas (Δngas)  is - 1. Calculate the difference (in kJ mol-1)  between ΔH (enthalpy change)  and ΔU (internal energy) .

Accepted Answer

A)   + 2.48.
B)   - 2.48.
C)   + 1.
D)   - 1.E) A) and B)
F) C) and D)

Question 4

The enthalpy change for the complete combustion of 1 mol of methane at 1 bar and 298 K is - 890.3 kJ mol-1.
Calculate  ΔcH∘\Delta_{\mathrm{c}} H^{\circ}Δc​H∘  at 335 K.
Mean Cp / J K-1 mol-1: CH4 (g)  35.7; O2 (g)  29.4; CO2 (g)  37.1; H2O (l)  75.3.

Accepted Answer

A)   - 890.3 kJ mol-1.
B)   - 859.1 kJ mol-1.
C)   - 888.8 kJ mol-1.
D)   - 886.9 kJ mol-1. E) All of the above
F) B) and D)

Question 5

Match the system name to its short description.
-Neither energy or matter can be exchanged with its surroundings

Accepted Answer

A)   Open
B)   Closed
C)   IsolatedD) A) and B)
E) None of the above

Question 6

The term heat capacity, C, is used to quantify heat changes; it can be defined in different ways. Match the short definition with the correct heat capacity symbol.
-Molar heat capacity is the heat needed to raise the temperature of 1 mol of substance by 1 K

Accepted Answer

A)   Cs
B)   Cm
C)   Cp
D)   CvE) None of the above
F) All of the above

Question 7

Calculate the enthalpy change at 298.15 K and 1 bar pressure for the following reaction, using  ΔfH208∘\Delta_{\mathrm{f}} H_{208}^{\circ}Δf​H208∘​  data in Appendix 7:
2 Cl (g)  → Cl2 (g)

Accepted Answer

A)   - 121.7 kJ mol-1.
B)   0 kJ mol-1.
C)   - 243.4 kJ mol-1.
D)   + 243.4 kJ mol-1. E) A) and D)
F) None of the above

Question 8

Calculate the enthalpy change at 298.15 K and 1 bar pressure for the following reaction, using  ΔfH208∘\Delta_{\mathrm{f}} H_{208}^{\circ}Δf​H208∘​  data in Appendix 7:
SiCl4 (l)  + 2H2O (l)  → SiO2 (s)  + 4 HCl (g)

Accepted Answer

A)   + 30.4 kJ mol-1.
B)   - 30.4 kJ mol-1.
C)   + 21.5 kJ mol-1.
D)   - 21.5 kJ mol-1. E) A) and D)
F) A) and C)

Question 9

When 1 mole of gas expands from a volume of 2.5 dm3 to 5 dm3 against a constant pressure of 1 atm, which of the following are true? Select all that apply.

Accepted Answer

A)   Work is done by the system.
B)   Work is done on the system.
C)   Energy is gained by the system.
D)   Energy is lost by the system.E) All of the above
F) C) and D)

Question 10

The combustion of ethanol (C2H5OH)  at 1 bar and 298 K releases 1367 kJ mol-1 of heat.
C2H5OH (l)  + 3 O2 (g)   2 CO2 (g)  + 3 H2O (l)  Calculate the standard enthalpy change of formation of ethanol (in kJ mol-1) . Use  ΔfH208∘\Delta_{\mathrm{f}} H_{208}^{\circ}Δf​H208∘​  data in Appendix 7.

Accepted Answer

A)   - 277.4
B)   + 277.4
C)   - 3011.4
D)   + 3011.4 E) A) and D)
F) A) and C)

Question 11

Match the system name to its short description.
-Both matter and energy can be exchanged with its surroundings

Accepted Answer

A)   Open
B)   Closed
C)   IsolatedD) None of the above
E) A) and C)

Question 12

Calculate the enthalpy change (in kJ mol-1)  when 1 mol of solid ethanol is melted at 155.8 K and heated to 298 K. (Take the molar heat capacity of liquid ethanol to be 112 J K-1 mol-1) ,  ΔfusH\Delta_{fus} HΔfus​H  (ethanol)  = + 4.60 kJ mol-1 and  ΔvapH\Delta_{vap} HΔvap​H  (ethanol)  = + 43.5 kJ mol-1.

Accepted Answer

A)   + 64.0
B)   + 20.5
C)   + 15.9
D)   + 38 E) None of the above
F) C) and D)

Question 13

Match the system name to its short description.
-Only energy can be exchanged with its surroundings

Accepted Answer

A)   Open
B)   Closed
C)   IsolatedD) A) and B)
E) None of the above

Question 14

The specific heat capacity of iron (Fe(s) )  is 0.45 J K-1 g-1, how much energy ( in J)  must be added to raise the temperature of a 250 g iron bar by 30 ° C?

Accepted Answer

A)   34.104.
B)   34104.
C)   3375.
D)   6 × 10-5.E) C) and D)
F) A) and C)

Question 15

Calculate the enthalpy change at 298.15 K and 1 bar pressure for the following reaction, using  ΔfH208∘\Delta_{\mathrm{f}} H_{208}^{\circ}Δf​H208∘​  data in Appendix 7:
CH4 (g)  + Cl2 (g)  → CH3Cl (g)  + HCl (g)

Accepted Answer

A)   - 101.2 kJ mol-1.
B)   + 101.2 kJ mol-1.
C)   - 250.8 kJ mol-1.
D)   250.8 kJ mol-1. E) B) and D)
F) None of the above

Question 16

The calibration factor of a bomb calorimeter was calculated to be 10.27 kJ K-1. Calculate the internal energy change of combustion  ΔcU\Delta_{c} UΔc​U  for glucose (Mr = 180.16)  if the combustion at 298 K of 1.228 g caused a temperature rise of 1.847 K.

Accepted Answer

A)   - 2783.
B)   + 19.
C)   - 19.
D)   + 2783. E) B) and C)
F) A) and B)

Question 17

The specific heat capacity of Cu (s)  is 0.38 J K-1 g-1 and that of Au (s)  is 0.129 J K-1 g-1. When 100 J of heat is added to 100 g of sample of each of these substances, will one experience a larger increase in temperature?

Accepted Answer

A)   Yes, gold.
B)   No.
C)   Yes, copper.
D)   Not enough energy to increase the temperature of either substance.E) None of the above
F) C) and D)

Question 18

The molar heat capacity, Cm of gold (Au(s) )  is 25.4 J K-1 mol-1. Calculate the energy (in J)  required to heat a 100 g bar of gold from 25 °C to 75 °C?

Accepted Answer

A)   Not possible to calculate.
B)   645.
C)   127000.
D)   1.E) B) and C)
F) None of the above

Question 19

The symbol  ΔcH∘\Delta_{\mathrm{c}} H^{\circ}Δc​H∘  conveys which of the following information? Select all that apply.

Accepted Answer

A)   Standard enthalpy change of combustion.
B)   Standard enthalpy change measured at 273.15 K.
C)   Enthalpy change measured at 1 bar pressure.
D)   Enthalpy change measured for 1 gram of substance. E) A) and B)
F) C) and D)

Question 20

Calculate the standard enthalpy change (in kJ mol-1)  for the hydrogenation of propene to propane at 298 K. The standard enthalpy change at 298 K for reactions of graphite and hydrogen gas to form 1 mol of each of these compounds is + 20.4 kJ mol-1 and - 103.9 kJ mol-1 respectively.

Accepted Answer

A)   + 83.5
B)   + 124.3
C)   - 83.5
D)   - 124.3E) None of the above
F) All of the above

Exam 13: Energy and Thermochemistry

The term heat capacity, C, is used to quantify heat changes; it can be defined in different ways. Match the short definition with the correct heat capacity symbol. -Molar heat capacity is the heat needed to raise the temperature of 1 mol of substance by 1 K

Correct AnswerverifiedShow Answer

The standard enthalpy change of fusion and vaporization for water are +6.01 kJ mol-1 and +40.7 kJ mol-1 respectively. Why is the value for vaporization so much larger than fusion?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

When 1 mole of gas expands from a volume of 2.5 dm3 to 5 dm3 against a constant pressure of 1 atm, which of the following are true? Select all that apply.

Correct AnswerverifiedShow Answer

The symbol ΔcH∘\Delta_{\mathrm{c}} H^{\circ}Δc​H∘ conveys which of the following information? Select all that apply.

Correct AnswerverifiedShow Answer

Match the system name to its short description. -Only energy can be exchanged with its surroundings

Correct AnswerverifiedShow Answer

Calculate the standard enthalpy change (in kJ mol-1) for the hydrogenation of propene to propane at 298 K. The standard enthalpy change at 298 K for reactions of graphite and hydrogen gas to form 1 mol of each of these compounds is + 20.4 kJ mol-1 and - 103.9 kJ mol-1 respectively.

Correct AnswerverifiedShow Answer

The molar heat capacity, Cm of gold (Au(s) ) is 25.4 J K-1 mol-1. Calculate the energy (in J) required to heat a 100 g bar of gold from 25 °C to 75 °C?

Correct AnswerverifiedShow Answer

Calculate the enthalpy change at 298.15 K and 1 bar pressure for the following reaction, using ΔfH208∘\Delta_{\mathrm{f}} H_{208}^{\circ}Δf​H208∘​ data in Appendix 7: SiCl4 (l) + 2H2O (l) → SiO2 (s) + 4 HCl (g)

Correct AnswerverifiedShow Answer

The specific heat capacity of Cu (s) is 0.38 J K-1 g-1 and that of Au (s) is 0.129 J K-1 g-1. When 100 J of heat is added to 100 g of sample of each of these substances, will one experience a larger increase in temperature?

Correct AnswerverifiedShow Answer

The enthalpy change for the complete combustion of 1 mol of methane at 1 bar and 298 K is - 890.3 kJ mol-1. Calculate ΔcH∘\Delta_{\mathrm{c}} H^{\circ}Δc​H∘ at 335 K. Mean Cp / J K-1 mol-1: CH4 (g) 35.7; O2 (g) 29.4; CO2 (g) 37.1; H2O (l) 75.3.

Correct AnswerverifiedShow Answer

For a reaction conducted at constant pressure and at 298 K the change in number of moles of gas (Δngas) is - 1. Calculate the difference (in kJ mol-1) between ΔH (enthalpy change) and ΔU (internal energy) .

Correct AnswerverifiedShow Answer

Calculate the enthalpy change at 298.15 K and 1 bar pressure for the following reaction, using ΔfH208∘\Delta_{\mathrm{f}} H_{208}^{\circ}Δf​H208∘​ data in Appendix 7: 2 Cl (g) → Cl2 (g)

Correct AnswerverifiedShow Answer

Match the system name to its short description. -Both matter and energy can be exchanged with its surroundings

Correct AnswerverifiedShow Answer

The combustion of ethanol (C2H5OH) at 1 bar and 298 K releases 1367 kJ mol-1 of heat. C2H5OH (l) + 3 O2 (g)  2 CO2 (g) + 3 H2O (l) Calculate the standard enthalpy change of formation of ethanol (in kJ mol-1) . Use ΔfH208∘\Delta_{\mathrm{f}} H_{208}^{\circ}Δf​H208∘​ data in Appendix 7.

Correct AnswerverifiedShow Answer

The calibration factor of a bomb calorimeter was calculated to be 10.27 kJ K-1. Calculate the internal energy change of combustion ΔcU\Delta_{c} UΔc​U for glucose (Mr = 180.16) if the combustion at 298 K of 1.228 g caused a temperature rise of 1.847 K.

Correct AnswerverifiedShow Answer

Match the system name to its short description. -Neither energy or matter can be exchanged with its surroundings

Correct AnswerverifiedShow Answer

Calculate the enthalpy change at 298.15 K and 1 bar pressure for the following reaction, using ΔfH208∘\Delta_{\mathrm{f}} H_{208}^{\circ}Δf​H208∘​ data in Appendix 7: CH4 (g) + Cl2 (g) → CH3Cl (g) + HCl (g)

Correct AnswerverifiedShow Answer

The specific heat capacity of iron (Fe(s) ) is 0.45 J K-1 g-1, how much energy ( in J) must be added to raise the temperature of a 250 g iron bar by 30 ° C?

Correct AnswerverifiedShow Answer

Thermodynamics is the study of systems on the microscopic scale. It explains the interrelation of energy and chemistry and relies on information about individual molecular properties to do this.

Correct AnswerverifiedShow Answer

Correct Answer
verified

The standard enthalpy change of fusion and vaporization for water are +6.01 kJ mol^-1 and +40.7 kJ mol^-1 respectively. Why is the value for vaporization so much larger than fusion?

Correct Answer
verified

Correct Answer
verified

When 1 mole of gas expands from a volume of 2.5 dm³ to 5 dm³ against a constant pressure of 1 atm, which of the following are true? Select all that apply.

Correct Answer
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The symbol $\Delta_{\mathrm{c}} H^{\circ}$ conveys which of the following information? Select all that apply.

Correct Answer
verified

Correct Answer
verified

Calculate the standard enthalpy change (in kJ mol^-1) for the hydrogenation of propene to propane at 298 K. The standard enthalpy change at 298 K for reactions of graphite and hydrogen gas to form 1 mol of each of these compounds is + 20.4 kJ mol^-1 and - 103.9 kJ mol^-1 respectively.

Correct Answer
verified

The molar heat capacity, C_m of gold (Au(s) ) is 25.4 J K^-1 mol^-1. Calculate the energy (in J) required to heat a 100 g bar of gold from 25 °C to 75 °C?

Correct Answer
verified

Calculate the enthalpy change at 298.15 K and 1 bar pressure for the following reaction, using $\Delta_{\mathrm{f}} H_{208}^{\circ}$ data in Appendix 7: SiCl₄ (l) + 2H₂O (l) → SiO₂ (s) + 4 HCl (g)

Correct Answer
verified

The specific heat capacity of Cu (s) is 0.38 J K^-1 g^-1 and that of Au (s) is 0.129 J K^-1 g^-1. When 100 J of heat is added to 100 g of sample of each of these substances, will one experience a larger increase in temperature?

Correct Answer
verified

The enthalpy change for the complete combustion of 1 mol of methane at 1 bar and 298 K is - 890.3 kJ mol^-1. Calculate $\Delta_{\mathrm{c}} H^{\circ}$ at 335 K. Mean C_p / J K^-1 mol^-1: CH₄ (g) 35.7; O₂ (g) 29.4; CO₂ (g) 37.1; H₂O (l) 75.3.

Correct Answer
verified

For a reaction conducted at constant pressure and at 298 K the change in number of moles of gas (Δn_gas) is - 1. Calculate the difference (in kJ mol^-1) between ΔH (enthalpy change) and ΔU (internal energy) .

Correct Answer
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Calculate the enthalpy change at 298.15 K and 1 bar pressure for the following reaction, using $\Delta_{\mathrm{f}} H_{208}^{\circ}$ data in Appendix 7: 2 Cl (g) → Cl₂ (g)

Correct Answer
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Correct Answer
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The combustion of ethanol (C₂H₅OH) at 1 bar and 298 K releases 1367 kJ mol^-1 of heat. C₂H₅OH (l) + 3 O₂ (g)  2 CO₂ (g) + 3 H₂O (l) Calculate the standard enthalpy change of formation of ethanol (in kJ mol^-1) . Use $\Delta_{\mathrm{f}} H_{208}^{\circ}$ data in Appendix 7.

Correct Answer
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The calibration factor of a bomb calorimeter was calculated to be 10.27 kJ K^-1. Calculate the internal energy change of combustion $\Delta_{c} U$ for glucose (M_r = 180.16) if the combustion at 298 K of 1.228 g caused a temperature rise of 1.847 K.

Correct Answer
verified

Correct Answer
verified

Calculate the enthalpy change at 298.15 K and 1 bar pressure for the following reaction, using $\Delta_{\mathrm{f}} H_{208}^{\circ}$ data in Appendix 7: CH₄ (g) + Cl₂ (g) → CH₃Cl (g) + HCl (g)

Correct Answer
verified

The specific heat capacity of iron (Fe(s) ) is 0.45 J K^-1 g^-1, how much energy ( in J) must be added to raise the temperature of a 250 g iron bar by 30 ° C?

Correct Answer
verified

Correct Answer
verified