Question 1

When 1.50 mol of CH4(g)  reacts with excess Cl2(g)  at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written. 
2CH4(g)  + 3Cl2(g)  → 2CHCl3(l)  + 3H2(g)  4(g)  reacts with excess Cl2(g)  at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written.  2CH4(g)  + 3Cl2(g)  → 2CHCl3(l)  + 3H2(g)    H° = ? A)  -1420 kJ   B)  -708 kJ   C)  +708 kJ   D)  +1420 kJ  " class="answers-bank-image d-inline" rel="preload" > H° = ?

Accepted Answer

A)   -1420 kJ 4(g)  reacts with excess Cl2(g)  at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written.  2CH4(g)  + 3Cl2(g)  → 2CHCl3(l)  + 3H2(g)    H° = ? 
A)   -1420 kJ   
B)   -708 kJ   
C)   +708 kJ   
D)   +1420 kJ  " class="answers-bank-image d-inline" rel="preload" >
B)   -708 kJ 4(g)  reacts with excess Cl2(g)  at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written.  2CH4(g)  + 3Cl2(g)  → 2CHCl3(l)  + 3H2(g)    H° = ? 
A)   -1420 kJ   
B)   -708 kJ   
C)   +708 kJ   
D)   +1420 kJ  " class="answers-bank-image d-inline" rel="preload" >
C)   +708 kJ 4(g)  reacts with excess Cl2(g)  at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written.  2CH4(g)  + 3Cl2(g)  → 2CHCl3(l)  + 3H2(g)    H° = ? 
A)   -1420 kJ   
B)   -708 kJ   
C)   +708 kJ   
D)   +1420 kJ  " class="answers-bank-image d-inline" rel="preload" >
D)   +1420 kJ 4(g)  reacts with excess Cl2(g)  at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written.  2CH4(g)  + 3Cl2(g)  → 2CHCl3(l)  + 3H2(g)    H° = ? 
A)   -1420 kJ   
B)   -708 kJ   
C)   +708 kJ   
D)   +1420 kJ  " class="answers-bank-image d-inline" rel="preload" >

Question 2

The water at the top of a waterfall contains ________ energy.

Accepted Answer

A)   kinetic
B)   thermal
C)   potential
D)   gravitational
E)   magnetic

Question 3

Explain the difference between ΔH and ΔU.

Accepted Answer

Change in enthalpy (ΔH) only tracks the ...

Question 4

Define chemical energy.

Accepted Answer

Chemical energy is the energy ...

Question 5

Which of the following is not a major contributor to energy consumption?

Accepted Answer

A)   residential
B)   commercial
C)   transportation
D)   industrial
E)   atmospheric

Question 6

An unknown metal alloy, specific heat capacity = 0.613 J g-1 °C-1, has a temperature change of 31.02 to 24.77 °C after a heat transfer of -106.4 J. Calculate the mass of the alloy in question.

Accepted Answer

A)   16.8 g
B)   12.7 g
C)   38.3 g
D)   27.8 g
E)   9.17 g

Question 7

Which of the following processes is exothermic?

Accepted Answer

A)   the formation of dew in the morning
B)   the melting of ice
C)   the chemical reaction in a "cold pack" often used to treat injuries
D)   the vaporization of water
E)   None of the above is exothermic.

Question 8

Calculate the final temperature of 68.4 g of molecular hydrogen (specific heat capacity = 14.304 J g-1 °C-1)  initially at 8.24 °C that releases 25.3 kJ of energy into the surroundings.

Accepted Answer

A)   34.1 °C
B)   17.6 °C
C)   -34.1 °C
D)   -17.6 °C
E)   -8.70 °C

Question 9

A piece of iron (C = 0.449 J g-1 °C-1 and a piece of gold (C = 0.128 J g-1 °C-1)  have identical masses. If the iron has an initial temperature of 498 K and the gold has an initial temperature of 298 K, which of the following statements is TRUE of the outcome when the two metals are placed in contact with one another? Assume no heat is lost to the surroundings.

Accepted Answer

A)   Since the two metals have the same mass, the final temperature of the two metals will be 398 K, exactly halfway between the two initial temperatures.
B)   Since the two metals have the same mass, but the specific heat capacity of gold is much smaller than that of iron, the final temperature of the two metals will be closer to 298 K than to 498 K.
C)   Since the two metals have the same mass, the thermal energy contained in the iron and gold after reaching thermal equilibrium will be the same.
D)   Since the two metals have the same mass, the thermal energy contained in each metal after equilibrium will be the same.
E)   None of the above is true.

Question 10

Describe the energy changes that occur when a book is held 1 m off the floor and then dropped.

Accepted Answer

The book starts out with a cer...

Question 11

A 35.6 g sample of ethanol (C2H5OH)  is burned in a bomb calorimeter according to the following reaction. If the temperature rose from 35.0 °C to 76.0°C and the heat capacity of the calorimeter is 23.3 kJ 2H5OH)  is burned in a bomb calorimeter according to the following reaction. If the temperature rose from 35.0 °C to 76.0°C and the heat capacity of the calorimeter is 23.3 kJ   , what is the value of ΔU°? The molar mass of ethanol is 46.07 g   . C2H5OH(l)  + 3O2(g)  → 2CO2(g)  + 3H2O(g)  ΔU° = ? A)  -1.24 × 103 kJ mol-1 B)  +1.24 × 103 kJ mol-1 C)  -8.09 × 103 kJ mol-1 D)  -9.55 × 103 kJ mol-1 E)  +9.55 × 103 kJ mol-1" class="answers-bank-image d-inline" rel="preload" > , what is the value of ΔU°? The molar mass of ethanol is 46.07 g 2H5OH)  is burned in a bomb calorimeter according to the following reaction. If the temperature rose from 35.0 °C to 76.0°C and the heat capacity of the calorimeter is 23.3 kJ   , what is the value of ΔU°? The molar mass of ethanol is 46.07 g   . C2H5OH(l)  + 3O2(g)  → 2CO2(g)  + 3H2O(g)  ΔU° = ? A)  -1.24 × 103 kJ mol-1 B)  +1.24 × 103 kJ mol-1 C)  -8.09 × 103 kJ mol-1 D)  -9.55 × 103 kJ mol-1 E)  +9.55 × 103 kJ mol-1" class="answers-bank-image d-inline" rel="preload" > . C2H5OH(l)  + 3O2(g)  → 2CO2(g)  + 3H2O(g)  ΔU° = ?

Accepted Answer

A)   -1.24 × 103 kJ mol-1
B)   +1.24 × 103 kJ mol-1
C)   -8.09 × 103 kJ mol-1
D)   -9.55 × 103 kJ mol-1
E)   +9.55 × 103 kJ mol-1

Question 12

Which of the following processes is endothermic?

Accepted Answer

A)   an atom emits a photon
B)   the condensation of water
C)   an atom absorbs a photon
D)   the electron affinity of a fluorine atom
E)   None of the above processes is endothermic.

Question 13

Define specific heat capacity.

Accepted Answer

A)   the quantity of heat required to raise the temperature of 1 mol of a substance by 1 °C
B)   the quantity of heat required to change a system's temperature by 1 °C
C)   the quantity of heat required to raise the temperature of 1 g of a substance by 1 °C
D)   the quantity of heat required to raise the temperature of 1 g of a substance by 1 °F
E)   the quantity of heat required to raise the temperature of 1 L of a substance by 1 °C

Question 14

Identify a substance that is in a non-standard state.

Accepted Answer

A)   O2
B)   Ca
C)   H
D)   Zn
E)   Ne

Question 15

Calculate the amount (mass)  of acetic acid (C2H4O2, molar mass = 60.052 g mol-1)  that causes a bomb calorimeter with a heat capacity of 8.43 kJ °C-1 to have a temperature increase from 24.5 °C to 36.8 °C. The ΔrU for the combustion of acetic acid is -874.2 kJ mol-1.

Accepted Answer

A)   6.18 g
B)   7.12 g
C)   2.18 g
D)   9.66 g
E)   8.68 g

Question 16

Calculate the internal energy change, ΔrU, for the combustion of 6.9261 g of diethylene glycol (C4H10O3, molar mass = 106.120 g mol-1)  if the combustion inside a bomb calorimeter, Ccal = 13.84 kJ °C-1, causes a temperature change from 22.8 °C to 34.0 °C.

Accepted Answer

A)   -4.39 × 103 kJ mol-1
B)   -9.16 × 102 kJ mol-1
C)   -2.37 × 103 kJ mol-1
D)   4.39 × 103 kJ mol-1
E)   1.18 × 103 kJ mol-1

Question 17

The specific heat of copper is 0.385 J   . If 34.2 g of copper, initially at 21.0 °C, absorbs 4.689 kJ, what will be the final temperature of the copper?

Accepted Answer

A)   21.4 °C
B)   23.8 °C
C)   356 °C
D)   377 °C

Question 18

The temperature rises from 25.00 °C to 29.00 °C when 3.50 g of sucrose undergoes combustion in a bomb calorimeter. Calculate 3 kJ mol-1 B)  1.92 × 103 kJ mol-1 C)  -1.23 × 103 kJ mol-1 D)  2.35 × 104 kJ mol-1" class="answers-bank-image d-inline" rel="preload" > U for the combustion of sucrose in kJ 3 kJ mol-1 B)  1.92 × 103 kJ mol-1 C)  -1.23 × 103 kJ mol-1 D)  2.35 × 104 kJ mol-1" class="answers-bank-image d-inline" rel="preload" > sucrose. The heat capacity of the calorimeter is 4.90 kJ 3 kJ mol-1 B)  1.92 × 103 kJ mol-1 C)  -1.23 × 103 kJ mol-1 D)  2.35 × 104 kJ mol-1" class="answers-bank-image d-inline" rel="preload" > . The molar mass of sugar is 342.3 g 3 kJ mol-1 B)  1.92 × 103 kJ mol-1 C)  -1.23 × 103 kJ mol-1 D)  2.35 × 104 kJ mol-1" class="answers-bank-image d-inline" rel="preload" > .

Accepted Answer

A)   -1.92 × 103 kJ mol-1
B)   1.92 × 103 kJ mol-1
C)   -1.23 × 103 kJ mol-1
D)   2.35 × 104 kJ mol-1

Question 19

If a reaction is carried out at constant volume, then the change in internal energy of the chemical reaction is equal to the ________.

Accepted Answer

A)   heat evolved
B)   work done by the system on the surroundings
C)   work done by the surroundings on the system
D)   heat evolved plus the work done by the surroundings
E)   heat capacity of the system

Question 20

An unknown metal alloy, mass = 36.1 g, has a temperature change of 31.6 to 24.8 °C after a heat transfer of -103.0 J. Calculate the specific heat capacity of the alloy.

Accepted Answer

A)   0.500 J g-1 °C-1
B)   0.384 J g-1 °C-1
C)   0.579 J g-1 °C-1
D)   0.420 J g-1 °C-1
E)   1.85 J g-1 °C-1

Exam 6: Thermochemistry

Correct Answer
verified

Calculate the internal energy change, Δ_rU, for the combustion of 6.9261 g of diethylene glycol (C₄H₁₀O₃, molar mass = 106.120 g mol^-1) if the combustion inside a bomb calorimeter, C_cal = 13.84 kJ °C^-1, causes a temperature change from 22.8 °C to 34.0 °C.

Correct Answer
verified

Which of the following processes is endothermic?

Correct Answer
verified

Correct Answer
verified

Define chemical energy.

Correct Answer
verified
Chemical energy is the energy ...
View Answer

The water at the top of a waterfall contains ________ energy.

Correct Answer
verified

Explain the difference between ΔH and ΔU.

Correct Answer
verified
Change in enthalpy (ΔH) only tracks the ...
View Answer

When 1.50 mol of CH₄(g) reacts with excess Cl₂(g) at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written. 2CH₄(g) + 3Cl₂(g) → 2CHCl₃(l) + 3H₂(g) H° = ?

Correct Answer
verified

Define specific heat capacity.

Correct Answer
verified

If a reaction is carried out at constant volume, then the change in internal energy of the chemical reaction is equal to the ________.

Correct Answer
verified

Which of the following is not a major contributor to energy consumption?

Correct Answer
verified

An unknown metal alloy, specific heat capacity = 0.613 J g^-1 °C^-1, has a temperature change of 31.02 to 24.77 °C after a heat transfer of -106.4 J. Calculate the mass of the alloy in question.

Correct Answer
verified

Calculate the amount (mass) of acetic acid (C₂H₄O₂, molar mass = 60.052 g mol^-1) that causes a bomb calorimeter with a heat capacity of 8.43 kJ °C^-1 to have a temperature increase from 24.5 °C to 36.8 °C. The Δ_rU for the combustion of acetic acid is -874.2 kJ mol^-1.

Correct Answer
verified

An unknown metal alloy, mass = 36.1 g, has a temperature change of 31.6 to 24.8 °C after a heat transfer of -103.0 J. Calculate the specific heat capacity of the alloy.

Correct Answer
verified

The specific heat of copper is 0.385 J . If 34.2 g of copper, initially at 21.0 °C, absorbs 4.689 kJ, what will be the final temperature of the copper?

Correct Answer
verified

Calculate the final temperature of 68.4 g of molecular hydrogen (specific heat capacity = 14.304 J g^-1 °C^-1) initially at 8.24 °C that releases 25.3 kJ of energy into the surroundings.

Correct Answer
verified

Describe the energy changes that occur when a book is held 1 m off the floor and then dropped.

Correct Answer
verified
The book starts out with a cer...
View Answer

Which of the following processes is exothermic?

Correct Answer
verified

The temperature rises from 25.00 °C to 29.00 °C when 3.50 g of sucrose undergoes combustion in a bomb calorimeter. Calculate U for the combustion of sucrose in kJ sucrose. The heat capacity of the calorimeter is 4.90 kJ . The molar mass of sugar is 342.3 g .

Correct Answer
verified

Identify a substance that is in a non-standard state.

Correct Answer
verified

Exam 6: Thermochemistry

Correct AnswerverifiedShow Answer

Calculate the internal energy change, ΔrU, for the combustion of 6.9261 g of diethylene glycol (C4H10O3, molar mass = 106.120 g mol-1) if the combustion inside a bomb calorimeter, Ccal = 13.84 kJ °C-1, causes a temperature change from 22.8 °C to 34.0 °C.

Correct AnswerverifiedShow Answer

Which of the following processes is endothermic?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Define chemical energy.

Correct AnswerverifiedChemical energy is the energy ...View AnswerShow Answer

The water at the top of a waterfall contains ________ energy.

Correct AnswerverifiedShow Answer

Explain the difference between ΔH and ΔU.

Correct AnswerverifiedChange in enthalpy (ΔH) only tracks the ...View AnswerShow Answer

When 1.50 mol of CH4(g) reacts with excess Cl2(g) at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written. 2CH4(g) + 3Cl2(g) → 2CHCl3(l) + 3H2(g) H° = ?

Correct AnswerverifiedShow Answer

Define specific heat capacity.

Correct AnswerverifiedShow Answer

If a reaction is carried out at constant volume, then the change in internal energy of the chemical reaction is equal to the ________.

Correct AnswerverifiedShow Answer

Which of the following is not a major contributor to energy consumption?

Correct AnswerverifiedShow Answer

An unknown metal alloy, specific heat capacity = 0.613 J g-1 °C-1, has a temperature change of 31.02 to 24.77 °C after a heat transfer of -106.4 J. Calculate the mass of the alloy in question.

Correct AnswerverifiedShow Answer

Calculate the amount (mass) of acetic acid (C2H4O2, molar mass = 60.052 g mol-1) that causes a bomb calorimeter with a heat capacity of 8.43 kJ °C-1 to have a temperature increase from 24.5 °C to 36.8 °C. The ΔrU for the combustion of acetic acid is -874.2 kJ mol-1.

Correct AnswerverifiedShow Answer

An unknown metal alloy, mass = 36.1 g, has a temperature change of 31.6 to 24.8 °C after a heat transfer of -103.0 J. Calculate the specific heat capacity of the alloy.

Correct AnswerverifiedShow Answer

The specific heat of copper is 0.385 J . If 34.2 g of copper, initially at 21.0 °C, absorbs 4.689 kJ, what will be the final temperature of the copper?

Correct AnswerverifiedShow Answer

Calculate the final temperature of 68.4 g of molecular hydrogen (specific heat capacity = 14.304 J g-1 °C-1) initially at 8.24 °C that releases 25.3 kJ of energy into the surroundings.

Correct AnswerverifiedShow Answer

Describe the energy changes that occur when a book is held 1 m off the floor and then dropped.

Correct AnswerverifiedThe book starts out with a cer...View AnswerShow Answer

Which of the following processes is exothermic?

Correct AnswerverifiedShow Answer

The temperature rises from 25.00 °C to 29.00 °C when 3.50 g of sucrose undergoes combustion in a bomb calorimeter. Calculate U for the combustion of sucrose in kJ sucrose. The heat capacity of the calorimeter is 4.90 kJ . The molar mass of sugar is 342.3 g .

Correct AnswerverifiedShow Answer

Identify a substance that is in a non-standard state.

Correct AnswerverifiedShow Answer

Correct Answer
verified

Calculate the internal energy change, Δ_rU, for the combustion of 6.9261 g of diethylene glycol (C₄H₁₀O₃, molar mass = 106.120 g mol^-1) if the combustion inside a bomb calorimeter, C_cal = 13.84 kJ °C^-1, causes a temperature change from 22.8 °C to 34.0 °C.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
Chemical energy is the energy ...
View Answer

Correct Answer
verified

Correct Answer
verified
Change in enthalpy (ΔH) only tracks the ...
View Answer

When 1.50 mol of CH₄(g) reacts with excess Cl₂(g) at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written. 2CH₄(g) + 3Cl₂(g) → 2CHCl₃(l) + 3H₂(g) H° = ?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

An unknown metal alloy, specific heat capacity = 0.613 J g^-1 °C^-1, has a temperature change of 31.02 to 24.77 °C after a heat transfer of -106.4 J. Calculate the mass of the alloy in question.

Correct Answer
verified

Calculate the amount (mass) of acetic acid (C₂H₄O₂, molar mass = 60.052 g mol^-1) that causes a bomb calorimeter with a heat capacity of 8.43 kJ °C^-1 to have a temperature increase from 24.5 °C to 36.8 °C. The Δ_rU for the combustion of acetic acid is -874.2 kJ mol^-1.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Calculate the final temperature of 68.4 g of molecular hydrogen (specific heat capacity = 14.304 J g^-1 °C^-1) initially at 8.24 °C that releases 25.3 kJ of energy into the surroundings.

Correct Answer
verified

Correct Answer
verified
The book starts out with a cer...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified