Deck 12: Thermodynamic Processes and Thermochemistry

Question 1

In chemistry applications, the change in internal energy is equal to

A) q + w
B) q - w
C) the molar constant pressure heat capacity.
D) 0
E) None of the above

Answer 1

A

Question 2

By definition DU_univ equals

A) DU_sys + DU_surr
B) -DU_sys
C) 0
D) a and c
E) none of the above

Answer 2

D

Question 3

The change in enthalpy for a reaction is

A) Equal to the constant volume heat capacity
B) DU / (nRT)
C) DU + PDV
D) a and b
E) none of the above

Answer 3

E

Question 4

A coffee cup calorimeter is best used to determine

A) q_p
B) q_v
C) DU
D) DH
E) a and d

Question 5

A bomb calorimeter is best used to determine

A) q_p
B) q_v
C) DU
D) DH
E) a and d
F) b and c

Question 6

Which of the following are acceptable units for heat capacity?

A) J·°K·mol^-1
B) J·°F^-1·mol^-1
C) J·°C^-1·g^-1
D) a and c
E) b and c

Question 7

When one combines a concentrated solution of a strong base with a concentrated solution of a strong acid, the beaker in which they are combined gets noticeably warmer. This reaction is therefore

A) endothermic
B) adiabatic
C) exothermic
D) isochoric
E) None of the above

Question 8

For an exothermic reaction which of the following must be true

A) DH_surr is positive
B) DH_surr is negative
C) DH_sys is positive
D) q is positive
E) b and c

Question 9

For an endothermic reaction which of the following must be true

A) DH_surr is positive
B) DH_surr is negative
C) DH_sys is positive
D) w_surr is positive
E) b and c

Question 10

Isochoric processes take place

A) at constant molar concentration
B) at constant pressure
C) at constant volume
D) in adiabatic system where PV work is being done.
E) None of the above

Question 11

For an isothermal process involving ideal gases

A) q = -w
B) DU > 0
C) q = 0
D) w = 0
E) a and b

Question 12

For a reversible isothermal process involving ideal gases

A) w = nRT ln

B) w =

C) w = -nRT

DV
D) b and c
E) all of the above

Question 13

For an adiabatic process involving ideal gases

A) q = w
B) w = 0
C) DU = 0
D) DU = w
E) a and d

Question 14

The molar heat capacity of a substance

A) will always be greater than the specific heat capacity.
B) will always be less than the specific heat capacity.
C) will equal the specific heat capacity if one mole of substance is used.
D) equals zero if the substance is an ideal gas.
E) a and d

Question 15

Which of the following is not a state function

A) U
B) P
C) V
D) H
E) PV
F) All of the above
G) None of the above

Question 16

At 298 K, elements in their standard state have

A) Zero enthalpy
B) Zero internal energy
C) A constant volume molar heat capacity equal to the internal energy
D) A constant pressure molar heat capacity equal to the enthalpy
E) None of the above

Question 17

Copper has a specific heat capacity of 0.0920 cal·K^-1·g^-1 at 298 K. What is the molar heat capacity of copper in J·K^-1·mol^-1?

A) 22.6 J·K^-1·mol^-1
B) 24.5 J·K^-1·mol^-1
C) 1.40 J·K^-1·mol^-1
D) 3.46×10^-4 J·K^-1·mol^-1
E) None of the above

Question 18

Titanium has a specific heat capacity of 0.515 J·K^-1·g^-1 at 298 K. How much energy is required to raise the temperature of 2.00 moles of Titanium by 50°C?

A) 2.47 kJ
B) 10.5 kJ
C) 1.23 kJ
D) 9.43 kJ
E) None of the above

Question 19

A 125.0 g piece of iron is heated to 400°C and placed in 300.0 g of water at 25°C. If the specific heat capacities of iron and water are 0.449 J·K^-1·g^-1 and 4.184 J·K^-1·g^-1 respectively, what will be the final temperature of the water?

A) 32°C
B) 41°C
C) 101°C
D) 383°C
E) None of the above

Question 20

When combusted, which of the following will produce the hottest flame?

A) H₃C-CH₃
B) H₂C=CH₂
C) HCºCH
D) The flame temperature will be the same for all of these

Question 21

The decomposition of NO and NO₂ to the elements proceeds via the following two reactions.
2NO(g) → N₂(g) + O₂(g) DH°rxn = -180 kJ
2NO₂(g) → N₂(g) + 2O₂(g) DH°rxn = -66.4 kJ
Calculate the enthalpy change for the reaction
2NO(g) + O₂(g) → 2NO₂(g)

A) 244 kJ
B) -244 kJ
C) -114 kJ
D) -293 kJ
E) none of the above

Question 22

Calculate the amount of energy necessary to raise the temperature of 1 cup of water at 23°C to steam at 105°C. The specific heat capacity of water is 4.184 J·K^-1·g^-1 and the specific heat capacity of steam is 4.215 J·K^-1·g^-1. The density of water can be assumed to be 1.00 g·ml^-1. For water, DH_vap=40.66 kJ·mol^-1. 1 cup=0.2366 L

A) 81.2 kJ
B) 122 kJ
C) 534 kJ
D) 616 kJ
E) None of the above

Question 23

Many residential microwave ovens operate at 900 watts. How long will it take a 900 watt microwave oven to raise the temperature of 1 cup of water at 23°C to steam at 105°C? The specific heat capacity of water is 4.184 J·K^-1·g^-1 and the specific heat capacity of steam is 4.215 J·K^-1·g^-1. The density of water can be assumed to be 1.00 g·ml^-1. For water, DH_vap=40.66 kJ·mol^-1. 1 cup=0.2366, 1 W=1 J·s^-1

A) 11.4 min
B) 38 seconds
C) 9.9 min
D) 1.5 min
E) None of the above

Question 24

Sublimation is the process of changing phases directly from a solid to a gas. Calculate DH°_sub for elemental iodine.

A) 62.44 kJ·mol^-1
B) -62.44 kJ·mol^-1
C) 39.98 kJ·mol^-1
D) 19.36 kJ·mol^-1

Question 25

Exhibit 12-1
The following question(s) pertain to the combustion of liquid ethanol (C₂H₅OH) to form carbon dioxide gas and water vapor.
Refer to Exhibit 12-1. For each mole of ethanol combusted, how many moles of carbon dioxide are formed?

A) 1
B) 2
C) 3
D) 4

Question 26

Exhibit 12-1
The following question(s) pertain to the combustion of liquid ethanol (C₂H₅OH) to form carbon dioxide gas and water vapor.
Refer to Exhibit 12-1. What is DH°_rxn for the combustion of ethanol?

A) -1367 kJ
B) -1235 kJ
C) -278 kJ
D) -913 kJ

Question 27

Exhibit 12-1
The following question(s) pertain to the combustion of liquid ethanol (C₂H₅OH) to form carbon dioxide gas and water vapor.
Refer to Exhibit 12-1. How much heat is liberated when 800.0 g of ethanol is combusted at 25°C?

A) 5370 kJ
B) 21500 kJ
C) 23800 kJ
D) 1370 kJ

Question 28

Exhibit 12-2
The following question(s) pertain to the reaction between aluminum metal and iron (III) oxide to produce iron metal and aluminum oxide.
Refer to Exhibit 12-2. In the balanced stoichiometric equation, how many moles of aluminum metal have to react with each mole of iron (III) oxide?

A) 1
B) 2
C) 3
D) 4

Question 29

Exhibit 12-2
The following question(s) pertain to the reaction between aluminum metal and iron (III) oxide to produce iron metal and aluminum oxide.
Refer to Exhibit 12-2. What is DH°_rxn for this reaction?

A) -1680 kJ
B) 851 kJ
C) -851 kJ
D) -2530 kJ

Question 30

Exhibit 12-2
The following question(s) pertain to the reaction between aluminum metal and iron (III) oxide to produce iron metal and aluminum oxide.
Refer to Exhibit 12-2. Calculate the enthalpy change when 200.0 grams of aluminum reacts with 300.0 grams of iron (III) oxide at 298 K.

A) -1600 kJ
B) -1520 kJ
C) -3141 kJ
D) 1520 kJ

Question 31

Which molecule has the highest total number of internal degrees of freedom?

A) C₆H₆
B) C₂H₅OH
C) C₂H₅OCH₃
D) A and C
E) Impossible to determine without structural information

Question 32

The constant pressure heat capacity (c_p) generally increases with

A) the mass of the molecule
B) the internal degrees of freedom in the molecule
C) the number of atoms in the molecule
D) A and C
E) B and C

Question 33

The standard state of carbon as a free element is graphite. C₆₀ is an allotropic form of carbon belonging to a class of structures known as fullerenes. for C₆₀ should be

A) zero
B) positive
C) negative
D) equal to
for the other allotropic forms of carbon
E) A and D