Question 1

What is the equation for the formation reaction for gaseous hydrazine, N2H4, at 25ºC and 1 atm pressure?

Accepted Answer

A)   2N2H4(g)  → 2NH3(g)  + H2(g) 
B)   2NH3(g)  + H2(g)  → N2H4(g) 
C)   N2(g)  + 2H2O(g)  → N2H4 (g)  + O2(g) 
D)   N2(g)  +2H2(g)  → N2H4(g) 
E)   2NO2(g)  + 6H2(g)  → N2H4(g)  + 4H2O(g) F) All of the above
G) C) and E)

Question 2

Using Hess' law, what is ΔH°rxn at 25°C for the following reaction? ClF(g)  + F2(g)  → ClF3(g)  rxn at 25°C for the following reaction? ClF(g)  + F2(g)  → ClF3(g)    A)  -217.5 kJ/mol B)  -130.2 kJ/mol C)  217.5 kJ/mol D)  -108.7 kJ/mol E)  465.4 kJ/mol" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   -217.5 kJ/mol
B)   -130.2 kJ/mol
C)   217.5 kJ/mol
D)   -108.7 kJ/mol
E)   465.4 kJ/molF) A) and C)
G) B) and E)

Question 3

In which reaction would you expect ΔH to be substantially greater than ΔU (i.e., ΔH > ΔU) ?

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) None of the above

Question 4

A system receives 575 J of heat and delivers 424 J of work. What is the change in the internal energy, ΔU, of the system?

Accepted Answer

A)   -150. J
B)   150. J
C)   -1000. J
D)   1000. J
E)   575 JF) B) and E)
G) B) and D)

Question 5

Using Hess's law, what is ΔH°rxn for the following reaction? WO3(s)  + 3H2(g)  → W(s)  + 3H2O(g)  rxn for the following reaction? WO3(s)  + 3H2(g)  → W(s)  + 3H2O(g)    A)  117.5 kJ/mol B)  235.0 kJ/mol C)  359.3 kJ/mol D)  1202.2 kJ/mol E)  2169.4 kJ/mol" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   117.5 kJ/mol
B)   235.0 kJ/mol
C)   359.3 kJ/mol
D)   1202.2 kJ/mol
E)   2169.4 kJ/molF) A) and C)
G) D) and E)

Question 6

In an endothermic reaction, in going from the reactants to the products at the same temperature, the value of q is negative.

Accepted Answer

A) True 
 B)False

Question 7

The heat absorbed by a system at constant pressure is equal to ΔU + PΔV.

Accepted Answer

A) True 
 B)False

Question 8

What is ΔH°rxn for the following reaction? H3AsO4(aq)  + 4H2(g)  → AsH3(g)  + 4H2O(l)  rxn for the following reaction? H3AsO4(aq)  + 4H2(g)  → AsH3(g)  + 4H2O(l)    A)  -1876.3 kJ/mol B)  -1018.9 kJ/mol C)  -790.3 kJ/mol D)  -410.1 kJ/mol E)  -67.1 kJ/mol" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   -1876.3 kJ/mol
B)   -1018.9 kJ/mol
C)   -790.3 kJ/mol
D)   -410.1 kJ/mol
E)   -67.1 kJ/molF) A) and B)
G) B) and D)

Question 9

What is ΔH°rxn for the reaction 2Al2O3(s)  → 4Al(s)  + 3O2(g) ? ΔH°f(Al2O3(s) )  = -1670 kJ/mol

Accepted Answer

A)   3340 kJ/mol
B)   1670 kJ/mol
C)   -3340 kJ/mol
D)   -1670 kJ/mol
E)   -835 kJ/molF) B) and E)
G) A) and D)

Question 10

Pentaborane B5H9(s)  burns vigorously in O2 to give B2O3(s)  and H2O(l) . What is ΔH° for the combustion of 1 mol of B5H9(s) ? Substance ΔH°f (kJ/mol) 
B2O3(s)  -1273.5
B5H9(s)  +73.2
H2O(l)  -285.8

Accepted Answer

A)   -1486.1 kJ
B)   -1632.5 kJ
C)   -4396.7 kJ
D)   -4652.85 kJ
E)   -9086.1 kJF) C) and D)
G) B) and E)

Question 11

How much heat is evolved if 0.600 kg of SO2 is burned in excess oxygen? 2SO2(g)  + O2(g)  → 2SO3(g)  ΔH°rxn= -198 kJ/mol

Accepted Answer

A)   5.46 × 10-2 kJ
B)   927 kJ
C)   1.85 × 103 kJ
D)   59,400 kJ
E)   3.71 × 103 kJF) A) and B)
G) A) and C)

Question 12

How much heat is required to raise the temperature of 1500 g of water from 25°C to 52°C? The specific heat of water is 4.184 J/g·°C.

Accepted Answer

A)   1500 kJ
B)   170 kJ
C)   6.3 kJ
D)   41 J
E)   41 kJF) A) and C)
G) A) and D)

Question 13

What is ΔH°rxn for the following reaction? SiO2(s)  + 4HCl(g)  → SiCl4(g)  + 2H2O(g)  rxn for the following reaction? SiO2(s)  + 4HCl(g)  → SiCl4(g)  + 2H2O(g)    A)  -1856.2 kJ/mol B)  -1372.6 kJ/mol C)  -47.0 kJ/mol D)  82.1 kJ/mol E)  530.6 kJ/mol" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   -1856.2 kJ/mol
B)   -1372.6 kJ/mol
C)   -47.0 kJ/mol
D)   82.1 kJ/mol
E)   530.6 kJ/molF) None of the above
G) B) and E)

Question 14

An ideal gas (the system)  is contained in a flexible balloon at a pressure of 1 atm and is initially at a temperature of 20.°C. The surrounding air is at the same pressure, but its temperature is 25°C. When the system has equilibrated with its surroundings, both system and surroundings are at 25°C and 1 atm. In changing from the initial to the final state, which one of the following relationships regarding the system is correct?

Accepted Answer

A)   ΔU 
B)   ΔU = 0
C)   ΔH = 0
D)   w > 0
E)   q > 0F) None of the above
G) B) and C)

Question 15

Solid sodium peroxide (Na2O2)  reacts with liquid water yielding aqueous sodium hydroxide and oxygen gas. How much heat is released if 327.2 g of oxygen gas is produced from the reaction of sodium peroxide and water under standard-state conditions? 2O2)  reacts with liquid water yielding aqueous sodium hydroxide and oxygen gas. How much heat is released if 327.2 g of oxygen gas is produced from the reaction of sodium peroxide and water under standard-state conditions?   A)  46,630 kJ B)  1457 kJ C)  6689 kJ D)  3345 kJ E)  2914 kJ" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   46,630 kJ
B)   1457 kJ
C)   6689 kJ
D)   3345 kJ
E)   2914 kJF) A) and D)
G) A) and E)

Question 16

A system which does work on the surroundings with no heat change has

Accepted Answer

A)   w = ΔU.
B)   w = -ΔU.
C)   w > 0, ΔU 
D)   w  0.
E)   w > ΔU.F) A) and D)
G) B) and C)

Question 17

A 100.-g sample of Cu is heated to 400.oC and then plunged into 1000. g of water at 22.6oC. What is the final temperature? Specific heat capacity: Cu: 0.385 J/g·°C;water: 4.184 J/g·°C

Accepted Answer

Question 18

For the reaction: 2A + B2 → 2AB ΔH = +50.0 kJ.

Accepted Answer

A)   The reaction is endothermic.
B)   Heat is released to the surroundings.
C)   The standard enthalpy of formation for AB is 50.0 kJ.
D)   The bond energy for each A-B bond is 50.0 kJ.
E)   The molecule AB contains less energy than A or B2.F) B) and E)
G) C) and D)

Question 19

Given the following ΔH° values
H2(g) + ½O2(g) → H2O(l) ΔH°f = -285.8 kJ
H2O2(l) → H2(g) + O2(g) ΔH°rxn = 187.6 kJ
calculate ΔH°rxn for the reaction H2O2(l) → H2O(l) + ½O2(g),

Accepted Answer

Question 20

Which equation has a ΔHrxn that is not equal to ΔHof of the product?

Accepted Answer

A)   O2(g)  + H2(g)  → H2O2(g) 
B)   ½O2(g)  + H2(g)  → H2O(g) 
C)   H2(g)  + ½O2(g)  + → H2O(l) 
D)   NO(g)  + ½O2(g)  → NO2(l) 
E)   ½H2(g)  + ½Cl2(g)  → HCl(g) F) All of the above
G) None of the above

Exam 5: Thermochemistry

In an endothermic reaction, in going from the reactants to the products at the same temperature, the value of q is negative.

Correct Answer
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Correct Answer
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A system which does work on the surroundings with no heat change has

Correct Answer
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Using Hess's law, what is ΔH°_rxn for the following reaction? WO₃(s) + 3H₂(g) → W(s) + 3H₂O(g)

Correct Answer
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What is the equation for the formation reaction for gaseous hydrazine, N₂H₄, at 25ºC and 1 atm pressure?

Correct Answer
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How much heat is required to raise the temperature of 1500 g of water from 25°C to 52°C? The specific heat of water is 4.184 J/g·°C.

Correct Answer
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Using Hess' law, what is ΔH°_rxnat 25°C for the following reaction? ClF(g) + F₂(g) → ClF₃(g)

Correct Answer
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Solid sodium peroxide (Na₂O₂) reacts with liquid water yielding aqueous sodium hydroxide and oxygen gas. How much heat is released if 327.2 g of oxygen gas is produced from the reaction of sodium peroxide and water under standard-state conditions?

Correct Answer
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Pentaborane B₅H₉(s) burns vigorously in O₂ to give B₂O₃(s) and H₂O(l) . What is ΔH° for the combustion of 1 mol of B₅H₉(s) ? Substance ΔH°_f (kJ/mol) B₂O₃(s) -1273.5 B₅H₉(s) +73.2 H₂O(l) -285.8

Correct Answer
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What is ΔH°_rxn for the following reaction? SiO₂(s) + 4HCl(g) → SiCl₄(g) + 2H₂O(g)

Correct Answer
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What is ΔH°_rxn for the following reaction? H₃AsO₄(aq) + 4H₂(g) → AsH₃(g) + 4H₂O(l)

Correct Answer
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The heat absorbed by a system at constant pressure is equal to ΔU + PΔV.

Correct Answer
verified

Which equation has a ΔH_rxn that is not equal to ΔH^o_f of the product?

Correct Answer
verified

Given the following ΔH° values H₂(g) + ½O₂(g) → H₂O(l) ΔH°_f = -285.8 kJ H₂O₂(l) → H₂(g) + O₂(g) ΔH°_rxn = 187.6 kJ calculate ΔH°_rxn for the reaction H₂O₂(l) → H₂O(l) + ½O₂(g),

Correct Answer
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What is ΔH°_rxn for the reaction 2Al₂O₃(s) → 4Al(s) + 3O₂(g) ? ΔH°_f(Al₂O₃(s) ) = -1670 kJ/mol

Correct Answer
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In which reaction would you expect ΔH to be substantially greater than ΔU (i.e., ΔH > ΔU) ?

Correct Answer
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A 100.-g sample of Cu is heated to 400.^oC and then plunged into 1000. g of water at 22.6^oC. What is the final temperature? Specific heat capacity: Cu: 0.385 J/g·°C;water: 4.184 J/g·°C

Correct Answer
verified

For the reaction: 2A + B₂→ 2AB ΔH = +50.0 kJ.

Correct Answer
verified

A system receives 575 J of heat and delivers 424 J of work. What is the change in the internal energy, ΔU, of the system?

Correct Answer
verified

How much heat is evolved if 0.600 kg of SO₂ is burned in excess oxygen? 2SO₂(g) + O₂(g) → 2SO₃(g) ΔH°_rxn= -198 kJ/mol

Correct Answer
verified

Exam 5: Thermochemistry

In an endothermic reaction, in going from the reactants to the products at the same temperature, the value of q is negative.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A system which does work on the surroundings with no heat change has

Correct AnswerverifiedShow Answer

Using Hess's law, what is ΔH°rxn for the following reaction? WO3(s) + 3H2(g) → W(s) + 3H2O(g)

Correct AnswerverifiedShow Answer

What is the equation for the formation reaction for gaseous hydrazine, N2H4, at 25ºC and 1 atm pressure?

Correct AnswerverifiedShow Answer

How much heat is required to raise the temperature of 1500 g of water from 25°C to 52°C? The specific heat of water is 4.184 J/g·°C.

Correct AnswerverifiedShow Answer

Using Hess' law, what is ΔH°rxn at 25°C for the following reaction? ClF(g) + F2(g) → ClF3(g)

Correct AnswerverifiedShow Answer

Solid sodium peroxide (Na2O2) reacts with liquid water yielding aqueous sodium hydroxide and oxygen gas. How much heat is released if 327.2 g of oxygen gas is produced from the reaction of sodium peroxide and water under standard-state conditions?

Correct AnswerverifiedShow Answer

Pentaborane B5H9(s) burns vigorously in O2 to give B2O3(s) and H2O(l) . What is ΔH° for the combustion of 1 mol of B5H9(s) ? Substance ΔH°f (kJ/mol) B2O3(s) -1273.5 B5H9(s) +73.2 H2O(l) -285.8

Correct AnswerverifiedShow Answer

What is ΔH°rxn for the following reaction? SiO2(s) + 4HCl(g) → SiCl4(g) + 2H2O(g)

Correct AnswerverifiedShow Answer

What is ΔH°rxn for the following reaction? H3AsO4(aq) + 4H2(g) → AsH3(g) + 4H2O(l)

Correct AnswerverifiedShow Answer

The heat absorbed by a system at constant pressure is equal to ΔU + PΔV.

Correct AnswerverifiedShow Answer

Which equation has a ΔHrxn that is not equal to ΔHof of the product?

Correct AnswerverifiedShow Answer

Given the following ΔH° values H2(g) + ½O2(g) → H2O(l) ΔH°f = -285.8 kJ H2O2(l) → H2(g) + O2(g) ΔH°rxn = 187.6 kJ calculate ΔH°rxn for the reaction H2O2(l) → H2O(l) + ½O2(g),

Correct AnswerverifiedShow Answer

What is ΔH°rxn for the reaction 2Al2O3(s) → 4Al(s) + 3O2(g) ? ΔH°f(Al2O3(s) ) = -1670 kJ/mol

Correct AnswerverifiedShow Answer

In which reaction would you expect ΔH to be substantially greater than ΔU (i.e., ΔH > ΔU) ?

Correct AnswerverifiedShow Answer

A 100.-g sample of Cu is heated to 400.oC and then plunged into 1000. g of water at 22.6oC. What is the final temperature? Specific heat capacity: Cu: 0.385 J/g·°C;water: 4.184 J/g·°C

Correct AnswerverifiedShow Answer

For the reaction: 2A + B2 → 2AB ΔH = +50.0 kJ.

Correct AnswerverifiedShow Answer

A system receives 575 J of heat and delivers 424 J of work. What is the change in the internal energy, ΔU, of the system?

Correct AnswerverifiedShow Answer

How much heat is evolved if 0.600 kg of SO2 is burned in excess oxygen? 2SO2(g) + O2(g) → 2SO3(g) ΔH°rxn= -198 kJ/mol

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Correct Answer
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Using Hess's law, what is ΔH°_rxn for the following reaction? WO₃(s) + 3H₂(g) → W(s) + 3H₂O(g)

Correct Answer
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What is the equation for the formation reaction for gaseous hydrazine, N₂H₄, at 25ºC and 1 atm pressure?

Correct Answer
verified

Correct Answer
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Using Hess' law, what is ΔH°_rxnat 25°C for the following reaction? ClF(g) + F₂(g) → ClF₃(g)

Correct Answer
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Solid sodium peroxide (Na₂O₂) reacts with liquid water yielding aqueous sodium hydroxide and oxygen gas. How much heat is released if 327.2 g of oxygen gas is produced from the reaction of sodium peroxide and water under standard-state conditions?

Correct Answer
verified

Pentaborane B₅H₉(s) burns vigorously in O₂ to give B₂O₃(s) and H₂O(l) . What is ΔH° for the combustion of 1 mol of B₅H₉(s) ? Substance ΔH°_f (kJ/mol) B₂O₃(s) -1273.5 B₅H₉(s) +73.2 H₂O(l) -285.8

Correct Answer
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What is ΔH°_rxn for the following reaction? SiO₂(s) + 4HCl(g) → SiCl₄(g) + 2H₂O(g)

Correct Answer
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What is ΔH°_rxn for the following reaction? H₃AsO₄(aq) + 4H₂(g) → AsH₃(g) + 4H₂O(l)

Correct Answer
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Correct Answer
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Which equation has a ΔH_rxn that is not equal to ΔH^o_f of the product?

Correct Answer
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Given the following ΔH° values H₂(g) + ½O₂(g) → H₂O(l) ΔH°_f = -285.8 kJ H₂O₂(l) → H₂(g) + O₂(g) ΔH°_rxn = 187.6 kJ calculate ΔH°_rxn for the reaction H₂O₂(l) → H₂O(l) + ½O₂(g),

Correct Answer
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What is ΔH°_rxn for the reaction 2Al₂O₃(s) → 4Al(s) + 3O₂(g) ? ΔH°_f(Al₂O₃(s) ) = -1670 kJ/mol

Correct Answer
verified

Correct Answer
verified

A 100.-g sample of Cu is heated to 400.^oC and then plunged into 1000. g of water at 22.6^oC. What is the final temperature? Specific heat capacity: Cu: 0.385 J/g·°C;water: 4.184 J/g·°C

Correct Answer
verified

For the reaction: 2A + B₂→ 2AB ΔH = +50.0 kJ.

Correct Answer
verified

Correct Answer
verified

How much heat is evolved if 0.600 kg of SO₂ is burned in excess oxygen? 2SO₂(g) + O₂(g) → 2SO₃(g) ΔH°_rxn= -198 kJ/mol

Correct Answer
verified