Deck 10: Overview of Combustion Chemistry

Question 1

Given the following data, calculate the heat of reaction (combustion) for one mole of butane, C₄H₁₀. Report your result in kJ/mol.
Standard heats of formation (kJ/mol):
H₂O(g): -241.82
CO₂(g): -393.5
Butane: -147.6
Formula weight of butane: 58.12 g/mol
L/mole of a gas at STP: 22.4L

A) -5272
B) 1831
C) -2636
D) -1831
E) none of the above

Answer 1

C

Question 2

Given the following data, calculate the heat of reaction (combustion) for one gram of butane, C₄H₁₀. Report your result in kJ/g.
Standard heats of formation (kJ/mole):
H₂O(g): -241.82
CO₂(g): -393.5
Butane: -147.6
Formula weight of butane: 58.12 g/mole
L/mole of a gas at STP: 22.4L

A) -45
B) 18
C) -91
D) -73
E) none of the above

Answer 2

A

Question 3

Given the following data, calculate how many moles of gas are produced in the combustion of one mole of butane, C₄H₁₀.
Standard heats of formation (kJ/mole):
H₂O(g): -241.82
CO₂(g): -393.5
Butane: -147.6
Formula weight of butane: 58.12 g/mole
L/mole of a gas at STP: 22.4L

A) 2
B) 5
C) 8
D) 9
E) none of the above

Answer 3

D

Question 4

Given the following data, calculate how many liters of gas are produced in the combustion of one mole of butane, C₄H₁₀. Report your result in L/mole and assume STP.
Standard heats of formation (kJ/mole):
H₂O(g): -241.82
CO₂(g): -393.5
Butane: -147.6
Formula weight of butane: 58.12 g/mole
L/mole of a gas at STP: 22.4L

A) 405
B) 202
C) 100
D) 9
E) none of the above

Question 5

Given the following data, calculate how many liters of gas are produced in the combustion of one gram of butane, C₄H₁₀. Report your result in L/g and assume STP.
Standard heats of formation (kJ/mole):
H₂O(g): -241.82
CO₂(g): -393.5
Butane: -147.6
Formula weight of butane: 58.12 g/mole
L/mole of a gas at STP: 22.4L

A) 7.2
B) 3.5
C) 12.8
D) 17.1
E) none of the above

Question 6

What are the components of the fire triangle?

A) fuel, heat, free radicals
B) light, heat, free radicals
C) oxygen, reducing agent, light
D) fuel, oxygen, heat
E) none of the above

Question 7

Combustion is a _______ reaction.

A) acid-base (gas phase)
B) phase change reaction
C) solution
D) free radical
E) none of the above

Question 8

Given the following reactions:
A. $\cdot \mathrm { HO } _ { 2 } + \mathrm { H } _ { 2 } \rightarrow \cdot \mathrm { H } + \mathrm { H } _ { 2 } \mathrm { O } _ { 2 }$
B. $\mathrm { HCO } + \cdot \mathrm { H } \rightarrow \mathrm { CH } _ { 2 } \mathrm { O }$
C. $\mathrm { C } _ { 2 } \mathrm { H } _ { 4 } \rightarrow \cdot \mathrm { CH } _ { 3 } \mathrm { CH }$
D. $\mathrm { CH } _ { 4 } + \mathrm { O } _ { 2 } \rightarrow \cdot \mathrm { CH } _ { 3 } + \cdot \mathrm { HO } _ { 2 }$ Which of these are termination steps?

A) A
B) B
C) C and D
D) A and C
E) none of the above

Question 9

Given the following reactions:
A. $\cdot \mathrm { HO } _ { 2 } + \mathrm { H } _ { 2 } \rightarrow \cdot \mathrm { H } + \mathrm { H } _ { 2 } \mathrm { O } _ { 2 }$
B. $\mathrm { HCO } + \cdot \mathrm { H } \rightarrow \mathrm { CH } _ { 2 } \mathrm { O }$
C. $\mathrm { C } _ { 2 } \mathrm { H } _ { 4 } \rightarrow \cdot \mathrm { CH } _ { 3 } \mathrm { CH }$
D. $\mathrm { CH } _ { 4 } + \mathrm { O } _ { 2 } \rightarrow \cdot \mathrm { CH } _ { 3 } + \cdot \mathrm { HO } _ { 2 }$ Which of these are propagation steps?

A) A
B) B
C) C and D
D) A and B
E) none of the above

Question 10

Given the following reactions:
A. $\cdot \mathrm { HO } _ { 2 } + \mathrm { H } _ { 2 } \rightarrow \cdot \mathrm { H } + \mathrm { H } _ { 2 } \mathrm { O } _ { 2 }$
B. $\mathrm { HCO } + \cdot \mathrm { H } \rightarrow \mathrm { CH } _ { 2 } \mathrm { O }$
C. $\mathrm { C } _ { 2 } \mathrm { H } _ { 4 } \rightarrow \cdot \mathrm { CH } _ { 3 } \mathrm { CH }$
D. $\mathrm { CH } _ { 4 } + \mathrm { O } _ { 2 } \rightarrow \cdot \mathrm { CH } _ { 3 } + \cdot \mathrm { HO } _ { 2 }$ Which of these are initiation steps?

A) C
B) B
C) C and D
D) A and C
E) none of the above

Question 11

What is the lowest temperature form of combustion?

A) flame
B) smoldering
C) deflagration
D) detonation
E) none of the above

Question 12

What is the process that starts a self-sustaining free radical combustion?

A) ignition
B) initiation
C) propagation
D) deflagration
E) none of the above

Question 13

The temperature at which a flammable mixture can ignite spontaneously is the

A) flashpoint
B) lower flammability limit
C) autoignition temperature
D) deflagration point
E) none of the above

Question 14

The lowest temperature at which a flammable liquid will sufficiently vaporize to produce a potentially flammable mixture is the

A) flashpoint
B) autoignition temperature
C) initiation temperature
D) deflagration temperature
E) none of the above

Question 15

When a hot expanding gas in an internal combustion engine causes a piston to move, this is an example of

A) TΔS work
B) PΔV work
C) Heat work
D) Kinetic work
E) none of the above

Question 16

When a gun is fired, what is the sequence of energy conversions?

A) heat to work energy
B) mechanical to electrical energy
C) kinetic energy to muzzle velocity
D) chemical energy kinetic energy
E) none of the above

Question 17

The relative power of combustibles to do PV work can be estimated by comparing what values?

A) TΔS
B) QV
C) Heats of formation
D) Heat capacities
E) none of the above

Question 18

When a simple combustion equation is balanced, the resulting amounts of the products are reactants are at

A) Equilibrium
B) Lean conditions
C) Stoichiometric equivalence
D) Rich conditions
E) none of the above

Question 19

When the equivalence ratio of fuel and air in a simple combustion is less than 1.0, this means that

A) the mixture is rich; more fuel than air
B) the mixture is lean; less fuel than air
C) the mixture is lean; more fuel than air
D) the mixture is rich; more air than fuel
E) none of the above

Question 20

At what value of the equivalence ratio is the maximum heat produced by a combustion?

A) < 1
B) 1.0
C) >1
D) depends on the fuel
E) none of the above

Question 21

The lower flammability (explosive limit) is

A) the minimum amount of fuel that can be combusted with 1 mole of oxygen
B) the smallest equivalence ratio that will support combustion
C) the minimum amount of fuel that can be combusted with 1 mole of air
D) the coolest temperature at which one mole of vapor will ignite
E) none of the above

Question 22

A warehouse has an enclosed volume of 500,000L. It is used to store propane cylinders. The LFL/LEL of propane by volume is 2.1%. How many liters of propane would have to leak from cylinders to generate a potentially flammable mixture?

A) 238,000
B) 10,500
C) 1,050
D) 23,800
E) none of the above

Question 23

Fundamentally, what drives mass transfer of oxygen and fuel in simple combustion?

A) concentration gradients
B) potential energy
C) heating of the products
D) heating of the reactants
E) none of the above

Question 24

Which of the following is not a means of heat transfer?

A) convection
B) particulate
C) radiant
D) conduction
E) none of the above

Question 25

Given the following data regarding octane:
Heat capacity: 255.6 J/(g °C)
Boiling point: 127°C
Heat of vaporization: 41.4 kJ/mole
AIT: 220°C
Density: 0.70 g/mL
Calculate the heat (Q) required to heat 15.0 mL of octane from room temperature (25°C) to the boiling point. Report the value in kJ

A) 274
B) 391
C) 87
D) 133
E) none of the above

Question 26

Given the following data regarding octane:
Heat capacity: 255.6 J/(g °C) for the liquid
Heat capacity
Boiling point: 127°C
Heat of vaporization: 41.4 kJ/mole
AIT: 220°C
Density: 0.70 g/mL
Calculate the heat (Q) required to convert 15.0 mL of octane at the boiling point temperature from liquid to gas. Report the value in kJ

A) 2.56
B) 1.3
C) 18.2
D) 3.8
E) none of the above

Question 27

Given the following data regarding octane:
Heat capacity: 255.6 J/(g °C)
Boiling point: 127°C
Heat of vaporization: 41.4 kJ/mole
AIT: 220°C
Density: 0.70 g/mL
Calculate the total heat (Q) required to heat 15.0 mL of octane from room temperature (25°C) to the AIT temperature. Report the value in kJ

A) 548
B) 523
C) 493
D) 681
E) none of the above

Question 28

Burning/deflagration transitions to detonation when

A) pressure reaches 10x atmospheric pressure
B) pressure reaches 100x atmospheric pressure
C) the reaction front propagation speed exceeds the speed of sound
D) the standard container is ruptured and explodes
E) none of the above

Question 29

A pressure wave moves forward from a combustion reaction. Because of the buildup of heat, a successive wave moves faster and eventually overtakes the first. This results in formation of a

A) pressure inversion
B) shockwave
C) deflagration
D) explosion
E) none of the above