Question 1

Sand is converted to pure silicon in a three step process. The third step is SiCl4(g)  + 2Mg(s)   →\rightarrow→ 2MgCl2(s)  + Si(s) ,  Δ\DeltaΔ H = -625.6 kJ
What is the enthalpy change when 25.0 mol of silicon tetrachloride is converted to elemental silicon?

Accepted Answer

A)   -25.0 kJ
B)   -7820 kJ
C)   -1.56 * 104 kJ
D)   -3.13 * 104 kJ
E)   None of these choices is correct. F) B) and C)
G) D) and E)

Question 2

Benzene is a starting material in the synthesis of nylon fibers and polystyrene (styrofoam) . Its specific heat capacity is 1.74 J/(g ? K) . If 16.7 kJ of energy is absorbed by a 225-g sample of benzene at 20.0 °\degree° C, what is its final temperature?

Accepted Answer

A)   -22.7 °\degree° C
B)   36.7 °\degree° C
C)   42.7 °\degree° C
D)   62.7 °\degree° C
E)   None of these choices is correct. F) A) and B)
G) B) and E)

Question 3

A system receives 575 J of heat and delivers 425 J of work. Calculate the change in the internal energy,  Δ\DeltaΔ E, of the system.

Accepted Answer

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

Question 4

A system delivers 1275 J of heat while the surroundings perform 855 J of work on it. Calculate  Δ\DeltaΔ E in J.

Accepted Answer

A)   -2130 J
B)   -420 J
C)   420 J
D)   2130 J
E)   -1275 J F) A) and D)
G) B) and E)

Question 5

Calculate, in J, the work done by 10.0 g of CO2 when it sublimes against a pressure of 1.00 atm to form gaseous CO2 at 0.0$\degree$C. The volume of CO2(s) can be neglected; CO2(g) can be assumed to behave ideally. The process occurring is CO2(s) $\rightarrow$CO2(g)

Accepted Answer

Question 6

A) State Hess's Law.
B) Use the $\Delta$H$\degree$
 data given below to calculate $\Delta$H$\degree$
or the reaction:
C2H4(g) + H2(g) $\rightarrow$ C2H6(g)

Accepted Answer

a. The enthalpy change for an ...

Question 7

Cold packs, whose temperatures are lowered when ammonium nitrate dissolves in water, are carried by athletic trainers when transporting ice is not possible. Which of the following is true of this reaction?

Accepted Answer

A)   ( Δ\DeltaΔ H 
B)   ( Δ\DeltaΔ H > 0, process is exothermic) 
C)   ( Δ\DeltaΔ H 
D)   ( Δ\DeltaΔ H > 0, process is endothermic) 
E)   ( Δ\DeltaΔ H = 0, since cold packs are sealed)  F) B) and C)
G) A) and D)

Question 8

The standard heat (enthalpy) of formation of graphite is zero.

Accepted Answer

A) True 
 B)False

Question 9

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 °\degree° C and placed into a calorimeter containing 72.4 g of water at 23.6 °\degree° C. The heat capacity of the calorimeter was 15.7 J/K. The final temperature in the calorimeter was 32.4 °\degree° 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 is correct. F) A) and E)
G) A) and B)

Question 10

Starting from equations relating pressure to force and force to work, derive the relationship w = -P$\Delta$V, explaining the steps in your argument.

Accepted Answer

Consider the system being contained in a...

Question 11

and does work on the surroundings has:

Accepted Answer

A)   w Δ\DeltaΔ E = 0
B)   w > 0,  Δ\DeltaΔ E > 0
C)   w > 0,  Δ\DeltaΔ E 
D)   w Δ\DeltaΔ E > 0
E)   w Δ\DeltaΔ E < 0 F) None of the above
G) C) and E)

Question 12

A system expands from a volume of 1.00 L to 2.00 L against a constant external pressure of 1.00 atm. The work (w)  done by the system, in J, is:

Accepted Answer

A)   1.00 J
B)   2.00 J
C)   1.01 * 102 J
D)   1.01 * 105 J
E)   None of these choices is correct.F) B) and C)
G) A) and D)

Question 13

A 275-g sample of nickel at 100.0 °\degree° C is placed in 100.0 mL of water at 22.0 °\degree° C. What is the final temperature of the water? Assume that no heat is lost to or gained from the surroundings. Specific heat capacity of nickel = 0.444 J/(g ? K)

Accepted Answer

A)   39.6 °\degree° C
B)   40.8 °\degree° C
C)   61.0 °\degree° C
D)   79.2 °\degree° C
E)   82.4 °\degree° C F) B) and E)
G) B) and D)

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. °\degree° C. The surrounding air is at the same pressure, but its temperature is 25 °\degree° C. When the system has equilibrated with its surroundings, both systems and surroundings are at 25 °\degree° 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)   ( Δ\DeltaΔ E 
B)   ( Δ\DeltaΔ E = 0) 
C)   ( Δ\DeltaΔ H = 0) 
D)   w > 0
E)   q > 0 F) A) and C)
G) B) and D)

Question 15

A system absorbs 21.6 kJ of heat while performing 6.9 kJ of work on the surroundings. If the initial internal energy, E, is 61.2 kJ, what is the final value of E?

Accepted Answer

A)   32.7 kJ
B)   46.5 kJ
C)   75.9 kJ
D)   82.8 kJ
E)   89.7 kJF) A) and C)
G) B) and D)

Question 16

A common laboratory reaction is the neutralization of an acid with a base. When 50.0 mL of 0.500 M HCl at 25.0 °\degree° C is added to 50.0 mL of 0.500 M NaOH at 25.0 °\degree° C in a coffee cup calorimeter, the temperature of the mixture rises to 28.2 °\degree° C. What is the heat of reaction per mole of acid? Assume the mixture has a specific heat capacity of 4.18 J/(g ? K)  and that the densities of the reactant solutions are both 1.00 g/mL.

Accepted Answer

A)   670 J
B)   1300 J
C)   27 kJ
D)   54 kJ
E)   > 100 kJ F) A) and E)
G) B) and D)

Question 17

Calculate the enthalpy change for the reaction  from the following data:

Accepted Answer

A)   -551.6 kJ
B)   -304.1 kJ
C)   190.9 kJ
D)   153.8 kJ
E)   438.4 kJF) A) and E)
G) B) and D)

Question 18

Although internal energy (E) is more fundamental and conceptually easier than enthalpy (H), in most chemical applications $\Delta$H is more relevant and useful than$\Delta$E. Why?

Accepted Answer

Most chemical processes of interest occu...

Question 19

$\Delta$E values obtained by bomb calorimetry can be converted to give accurate $\Delta$H values.

Accepted Answer

A) True 
 B)False

Question 20

Calculate the  Δ\DeltaΔ Hf °\degree° rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide. 
 Δ\DeltaΔ Hf  °\degree° [CaCO3(s) ] = -1206.9 kJ/mol;  Δ\DeltaΔ Hf °\degree° [CaO(s) ] = -635.1 kJ/mol;  Δ\DeltaΔ HfB0 [CO2(g) ] = -393.5 kJ/mol. CaCO3(s)  →\rightarrow→ CaO(s)  + CO2(g)

Accepted Answer

A)   -2235.5 kJ
B)   -1448.5 kJ
C)   -178.3 kJ
D)   178.3 kJ
E)   2235.5 kJ F) C) and E)
G) A) and B)

Exam 6: Thermochemistry: Energy Flow and Chemical Change

A system absorbs 21.6 kJ of heat while performing 6.9 kJ of work on the surroundings. If the initial internal energy, E, is 61.2 kJ, what is the final value of E?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Sand is converted to pure silicon in a three step process. The third step is SiCl₄(g) + 2Mg(s) $\rightarrow$ 2MgCl₂(s) + Si(s) , $\Delta$ H = -625.6 kJ What is the enthalpy change when 25.0 mol of silicon tetrachloride is converted to elemental silicon?

Correct Answer
verified

Cold packs, whose temperatures are lowered when ammonium nitrate dissolves in water, are carried by athletic trainers when transporting ice is not possible. Which of the following is true of this reaction?

Correct Answer
verified

Calculate the enthalpy change for the reaction from the following data:

Correct Answer
verified

and does work on the surroundings has:

Correct Answer
verified

Calculate, in J, the work done by 10.0 g of CO₂ when it sublimes against a pressure of 1.00 atm to form gaseous CO₂ at 0.0 $\degree$ C. The volume of CO₂(s) can be neglected; CO₂(g) can be assumed to behave ideally. The process occurring is CO₂(s) $\rightarrow$ CO₂(g)

Correct Answer
verified

Correct Answer
verified
a. The enthalpy change for an ...
View Answer

Correct Answer
verified

Correct Answer
verified

The standard heat (enthalpy) of formation of graphite is zero.

Correct Answer
verified

A system receives 575 J of heat and delivers 425 J of work. Calculate the change in the internal energy, $\Delta$ E, of the system.

Correct Answer
verified

Benzene is a starting material in the synthesis of nylon fibers and polystyrene (styrofoam) . Its specific heat capacity is 1.74 J/(g ? K) . If 16.7 kJ of energy is absorbed by a 225-g sample of benzene at 20.0 $\degree$ C, what is its final temperature?

Correct Answer
verified

$\Delta$ E values obtained by bomb calorimetry can be converted to give accurate $\Delta$ H values.

Correct Answer
verified

A system delivers 1275 J of heat while the surroundings perform 855 J of work on it. Calculate $\Delta$ E in J.

Correct Answer
verified

Although internal energy (E) is more fundamental and conceptually easier than enthalpy (H), in most chemical applications $\Delta$ H is more relevant and useful than $\Delta$ E. Why?

Correct Answer
verified
Most chemical processes of interest occu...
View Answer

Starting from equations relating pressure to force and force to work, derive the relationship w = -P $\Delta$ V, explaining the steps in your argument.

Correct Answer
verified
Consider the system being contained in a...
View Answer

A system expands from a volume of 1.00 L to 2.00 L against a constant external pressure of 1.00 atm. The work (w) done by the system, in J, is:

Correct Answer
verified

A 275-g sample of nickel at 100.0 $\degree$ C is placed in 100.0 mL of water at 22.0 $\degree$ C. What is the final temperature of the water? Assume that no heat is lost to or gained from the surroundings. Specific heat capacity of nickel = 0.444 J/(g ? K)

Correct Answer
verified

Exam 6: Thermochemistry: Energy Flow and Chemical Change

A system absorbs 21.6 kJ of heat while performing 6.9 kJ of work on the surroundings. If the initial internal energy, E, is 61.2 kJ, what is the final value of E?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Sand is converted to pure silicon in a three step process. The third step is SiCl4(g) + 2Mg(s) →\rightarrow→ 2MgCl2(s) + Si(s) , Δ\DeltaΔ H = -625.6 kJ What is the enthalpy change when 25.0 mol of silicon tetrachloride is converted to elemental silicon?

Correct AnswerverifiedShow Answer

Cold packs, whose temperatures are lowered when ammonium nitrate dissolves in water, are carried by athletic trainers when transporting ice is not possible. Which of the following is true of this reaction?

Correct AnswerverifiedShow Answer

Calculate the enthalpy change for the reaction from the following data:

Correct AnswerverifiedShow Answer

and does work on the surroundings has:

Correct AnswerverifiedShow Answer

Calculate, in J, the work done by 10.0 g of CO2 when it sublimes against a pressure of 1.00 atm to form gaseous CO2 at 0.0 °\degree° C. The volume of CO2(s) can be neglected; CO2(g) can be assumed to behave ideally. The process occurring is CO2(s) →\rightarrow→ CO2(g)

Correct AnswerverifiedShow Answer

A) State Hess's Law. B) Use the Δ\DeltaΔ H °\degree° data given below to calculate Δ\DeltaΔ H °\degree° or the reaction: C2H4(g) + H2(g) →\rightarrow→ C2H6(g)

Correct Answerverifieda. The enthalpy change for an ...View AnswerShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

The standard heat (enthalpy) of formation of graphite is zero.

Correct AnswerverifiedShow Answer

A system receives 575 J of heat and delivers 425 J of work. Calculate the change in the internal energy, Δ\DeltaΔ E, of the system.

Correct AnswerverifiedShow Answer

Benzene is a starting material in the synthesis of nylon fibers and polystyrene (styrofoam) . Its specific heat capacity is 1.74 J/(g ? K) . If 16.7 kJ of energy is absorbed by a 225-g sample of benzene at 20.0 °\degree° C, what is its final temperature?

Correct AnswerverifiedShow Answer

Δ\DeltaΔ E values obtained by bomb calorimetry can be converted to give accurate Δ\DeltaΔ H values.

Correct AnswerverifiedShow Answer

A system delivers 1275 J of heat while the surroundings perform 855 J of work on it. Calculate Δ\DeltaΔ E in J.

Correct AnswerverifiedShow Answer

Although internal energy (E) is more fundamental and conceptually easier than enthalpy (H), in most chemical applications Δ\DeltaΔ H is more relevant and useful than Δ\DeltaΔ E. Why?

Correct AnswerverifiedMost chemical processes of interest occu...View AnswerShow Answer

Starting from equations relating pressure to force and force to work, derive the relationship w = -P Δ\DeltaΔ V, explaining the steps in your argument.

Correct AnswerverifiedConsider the system being contained in a...View AnswerShow Answer

A system expands from a volume of 1.00 L to 2.00 L against a constant external pressure of 1.00 atm. The work (w) done by the system, in J, is:

Correct AnswerverifiedShow Answer

A 275-g sample of nickel at 100.0 °\degree° C is placed in 100.0 mL of water at 22.0 °\degree° C. What is the final temperature of the water? Assume that no heat is lost to or gained from the surroundings. Specific heat capacity of nickel = 0.444 J/(g ? K)

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Sand is converted to pure silicon in a three step process. The third step is SiCl₄(g) + 2Mg(s) $\rightarrow$ 2MgCl₂(s) + Si(s) , $\Delta$ H = -625.6 kJ What is the enthalpy change when 25.0 mol of silicon tetrachloride is converted to elemental silicon?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Calculate, in J, the work done by 10.0 g of CO₂ when it sublimes against a pressure of 1.00 atm to form gaseous CO₂ at 0.0 $\degree$ C. The volume of CO₂(s) can be neglected; CO₂(g) can be assumed to behave ideally. The process occurring is CO₂(s) $\rightarrow$ CO₂(g)

Correct Answer
verified

Correct Answer
verified
a. The enthalpy change for an ...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

A system receives 575 J of heat and delivers 425 J of work. Calculate the change in the internal energy, $\Delta$ E, of the system.

Correct Answer
verified

Benzene is a starting material in the synthesis of nylon fibers and polystyrene (styrofoam) . Its specific heat capacity is 1.74 J/(g ? K) . If 16.7 kJ of energy is absorbed by a 225-g sample of benzene at 20.0 $\degree$ C, what is its final temperature?

Correct Answer
verified

$\Delta$ E values obtained by bomb calorimetry can be converted to give accurate $\Delta$ H values.

Correct Answer
verified

A system delivers 1275 J of heat while the surroundings perform 855 J of work on it. Calculate $\Delta$ E in J.

Correct Answer
verified

Although internal energy (E) is more fundamental and conceptually easier than enthalpy (H), in most chemical applications $\Delta$ H is more relevant and useful than $\Delta$ E. Why?

Correct Answer
verified
Most chemical processes of interest occu...
View Answer

Starting from equations relating pressure to force and force to work, derive the relationship w = -P $\Delta$ V, explaining the steps in your argument.

Correct Answer
verified
Consider the system being contained in a...
View Answer

Correct Answer
verified

A 275-g sample of nickel at 100.0 $\degree$ C is placed in 100.0 mL of water at 22.0 $\degree$ C. What is the final temperature of the water? Assume that no heat is lost to or gained from the surroundings. Specific heat capacity of nickel = 0.444 J/(g ? K)

Correct Answer
verified