Question 1

Ethanol, C2H5OH, is being promoted as a clean fuel and is used as an additive in many gasoline mixtures. Calculate the ΔH°rxn for the combustion of ethanol. (ΔH°f [C2H5OH(l) ] = -277.7 kJ/mol; ΔH°f [CO2(g) ] = -393.5 kJ/mol; ΔH°f [H2O(g) ] = -241.8 kJ/mol)

Accepted Answer

A)   -1234.7 kJ
B)   -751.1 kJ
C)   -357.6 kJ
D)   357.6 kJ
E)   1234.7 kJF) A) and E)
G) A) and C)

Question 2

A system that does no work but that transfers heat to the surroundings has

Accepted Answer

A)   q  0.
B)   q 
C)   q > 0, ΔE > 0.
D)   q > 0, ΔE 
E)   q < 0, ΔE = 0.F) A) and E)
G) B) and E)

Question 3

In which one of the following processes is ΔH = ΔE?

Accepted Answer

A)   2HI(g)  → H2(g)  + I2(g)  at atmospheric pressure.
B)   Two moles of ammonia gas are cooled from 325 °C to 300 °C at 1.2 atm.
C)   H2O(l)  → H2O(g)  at 100 °C at atmospheric pressure.
D)   CaCO3(s)  → CaO(s)  + CO2(g)  at 800 °C at atmospheric pressure.
E)   CO2(s)  → CO2(g)  at atmospheric pressure.F) B) and E)
G) C) and D)

Question 4

The Starship Enterprise is caught in a time warp and Spock is forced to use the primitive techniques of the 20th century to determine the specific heat capacity of an unknown mineral. The 307-g sample was heated to 98.7°C and placed into a calorimeter containing 72.4 g of water at 23.6°C. The heat capacity of the calorimeter was 15.7 J/K. The final temperature in the calorimeter was 32.4°C. What is the specific heat capacity of the mineral?

Accepted Answer

A)   0.124 J/(g·K) 
B)   0.131 J/(g·K) 
C)   0.138 J/(g·K) 
D)   0.145 J/(g·K) 
E)   None of these choices are correct.F) A) and E)
G) A) and D)

Question 5

In which one of the following reactions would you expect ΔH to be substantially greater than ΔE (i.e., ΔH > ΔE) ?

Accepted Answer

A)   H2(g)  + Br2(g)  → 2HBr(g) 
B)   CO2(s)  → CO2(g) 
C)   C2H2(g)  + H2(g)  → C2H4(g) 
D)   H2O(s)  → H2O(l) 
E)   HCl(aq)  + NaOH(aq)  → NaCl(aq)  + H2O(l) F) A) and B)
G) A) and E)

Question 6

Which one of the following relationships is always correct?

Accepted Answer

A)   potential energy + kinetic energy = constant
B)   E = q + w
C)   ΔE = ΔH - PΔV
D)   H = E + PV
E)   ΔH = qvF) All of the above
G) A) and E)

Question 7

When Karl Kaveman adds chilled grog to his new granite mug, he removes 10.9 kJ of energy from the mug. If it has a mass of 625 g and was at 25°C, what is its new temperature? Specific heat capacity of granite = 0.79 J/(g·K)

Accepted Answer

A)   3°C
B)   14°C
C)   22°C
D)   47°C
E)   None of these choices are correct.F) B) and C)
G) A) and E)

Question 8

For which one of the following reactions will ΔH be approximately (or exactly)  equal to ΔE?

Accepted Answer

A)   H2(g)  + Br2(g)  → 2HBr(g) 
B)   H2O(l)  → H2O(g) 
C)   CaCO3(s)  → CaO(s)  + CO2(g) 
D)   2H(g)  + O(g)  → H2O(l) 
E)   CH4(g)  + 2O2(g)  → CO2(g)  + 2H2O(l) F) A) and E)
G) B) and E)

Question 9

For all processes, both q and ΔE will have the same sign.

Accepted Answer

A) True 
 B)False

Question 10

Use Hess's Law to calculate the enthalpy change for the reaction WO3(s)  + 3H2(g)  → W(s)  + 3H2O(g) 
From the following data:
2W(s)  + 3O2(g)  → 2WO3(s)  ΔH = -1685.4 kJ
2H2(g)  + O2(g)  → 2H2O(g)  ΔH = -477.84 kJ

Accepted Answer

A)   125.9 kJ
B)   252.9 kJ
C)   364.9 kJ
D)   1207.6 kJ
E)   None of these choices are correct.F) A) and D)
G) A) and C)

Question 11

In a reaction with high energy reactants and low energy products, q is negative.

Accepted Answer

A) True 
 B)False

Question 12

Natural gas, or methane, is an important fuel. Combustion of one mole of methane releases 802.3 kilojoules of energy. How much energy does that represent in kilocalories?

Accepted Answer

A)   1.92 × 10-1 kcal
B)   1.92 × 102 kcal
C)   3.36 × 103 kcal
D)   1.92 × 105 kcal
E)   3.36 × 106 kcalF) C) and D)
G) B) and D)

Exam 6: Thermochemistry Energy Flow and Chemical Change

For which one of the following reactions will ΔH be approximately (or exactly) equal to ΔE?

Correct Answer
verified

In a reaction with high energy reactants and low energy products, q is negative.

Correct Answer
verified

In which one of the following processes is ΔH = ΔE?

Correct Answer
verified

Ethanol, C₂H₅OH, is being promoted as a clean fuel and is used as an additive in many gasoline mixtures. Calculate the ΔH°_rxn for the combustion of ethanol. (ΔH°_f [C₂H₅OH(l) ] = -277.7 kJ/mol; ΔH°_f [CO₂(g) ] = -393.5 kJ/mol; ΔH°_f [H2O(g) ] = -241.8 kJ/mol)

Correct Answer
verified

A system that does no work but that transfers heat to the surroundings has

Correct Answer
verified

Which one of the following relationships is always correct?

Correct Answer
verified

Natural gas, or methane, is an important fuel. Combustion of one mole of methane releases 802.3 kilojoules of energy. How much energy does that represent in kilocalories?

Correct Answer
verified

In which one of the following reactions would you expect ΔH to be substantially greater than ΔE (i.e., ΔH > ΔE) ?

Correct Answer
verified

Correct Answer
verified

When Karl Kaveman adds chilled grog to his new granite mug, he removes 10.9 kJ of energy from the mug. If it has a mass of 625 g and was at 25°C, what is its new temperature? Specific heat capacity of granite = 0.79 J/(g·K)

Correct Answer
verified

Use Hess's Law to calculate the enthalpy change for the reaction WO₃(s) + 3H₂(g) → W(s) + 3H₂O(g) From the following data: 2W(s) + 3O₂(g) → 2WO₃(s) ΔH = -1685.4 kJ 2H₂(g) + O₂(g) → 2H₂O(g) ΔH = -477.84 kJ

Correct Answer
verified

For all processes, both q and ΔE will have the same sign.

Correct Answer
verified

Exam 6: Thermochemistry Energy Flow and Chemical Change

For which one of the following reactions will ΔH be approximately (or exactly) equal to ΔE?

Correct AnswerverifiedShow Answer

In a reaction with high energy reactants and low energy products, q is negative.

Correct AnswerverifiedShow Answer

In which one of the following processes is ΔH = ΔE?

Correct AnswerverifiedShow Answer

Ethanol, C2H5OH, is being promoted as a clean fuel and is used as an additive in many gasoline mixtures. Calculate the ΔH°rxn for the combustion of ethanol. (ΔH°f [C2H5OH(l) ] = -277.7 kJ/mol; ΔH°f [CO2(g) ] = -393.5 kJ/mol; ΔH°f [H2O(g) ] = -241.8 kJ/mol)

Correct AnswerverifiedShow Answer

A system that does no work but that transfers heat to the surroundings has

Correct AnswerverifiedShow Answer

Which one of the following relationships is always correct?

Correct AnswerverifiedShow Answer

Natural gas, or methane, is an important fuel. Combustion of one mole of methane releases 802.3 kilojoules of energy. How much energy does that represent in kilocalories?

Correct AnswerverifiedShow Answer

In which one of the following reactions would you expect ΔH to be substantially greater than ΔE (i.e., ΔH > ΔE) ?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

When Karl Kaveman adds chilled grog to his new granite mug, he removes 10.9 kJ of energy from the mug. If it has a mass of 625 g and was at 25°C, what is its new temperature? Specific heat capacity of granite = 0.79 J/(g·K)

Correct AnswerverifiedShow Answer

Use Hess's Law to calculate the enthalpy change for the reaction WO3(s) + 3H2(g) → W(s) + 3H2O(g) From the following data: 2W(s) + 3O2(g) → 2WO3(s) ΔH = -1685.4 kJ 2H2(g) + O2(g) → 2H2O(g) ΔH = -477.84 kJ

Correct AnswerverifiedShow Answer

For all processes, both q and ΔE will have the same sign.

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Ethanol, C₂H₅OH, is being promoted as a clean fuel and is used as an additive in many gasoline mixtures. Calculate the ΔH°_rxn for the combustion of ethanol. (ΔH°_f [C₂H₅OH(l) ] = -277.7 kJ/mol; ΔH°_f [CO₂(g) ] = -393.5 kJ/mol; ΔH°_f [H2O(g) ] = -241.8 kJ/mol)

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Use Hess's Law to calculate the enthalpy change for the reaction WO₃(s) + 3H₂(g) → W(s) + 3H₂O(g) From the following data: 2W(s) + 3O₂(g) → 2WO₃(s) ΔH = -1685.4 kJ 2H₂(g) + O₂(g) → 2H₂O(g) ΔH = -477.84 kJ

Correct Answer
verified

Correct Answer
verified