CHM 2045C Module Seven Sample Exam
Part M Multiple Choice

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1. The quantity of heat needed to raise the temperature of 46.1 g of ethanol, C2H5OH, 1?C is called its

a.

specific heat.

b.

molar enthalpy.

c.

molar entropy.

d.

molar heat capacity.

e.

specific heat per mole.


2. Given the following specific heats of metals:

If the same amount of heat is added to 75.0-g samples of each of the metals, which are all at the same temperature, which metal will have the lowest temperature?

a.

Copper

b.

Magnesium

c.

Mercury

d.

Silver

e.

Lead


3. What is the specific heat of ethanol in J/g?C if 560.0 J of heat is required to raise the temperature from 22.0?C to 37.0?C for a 64.0-g sample?

a.

0.194

b.

0.292

c.

0.583

d.

1.72

e.

8.75



4. A 150.0-g sample of metal at 80.0?C is added to 150.0 g of H2O at 20.0?C. The temperature rises to 23.3?C. Assuming that the calorimeter is a perfect insulator, what is the specific heat of the metal? (Specific heat of H2O is 4.18 J/g?C.)

a.

-0.48 J/g?C

b.

0.24 J/g?C

c.

0.48 J/g?C

d.

0.72 J/g?C

e.

0.96 J/g?C



5. The reaction of zinc with silver nitrate is represented by the equation

Zn(s) + 2AgNO3(aq) --> 2Ag(s) + Zn(NO3)2(aq)

The reaction is exothermic. In which of the following experiments would the temperature rise be the greatest?

a.

0.65 g of Zn added to 1.0 L of 0.010 M AgNO3

b.

1.3 g of Zn added to 1.0 L of 0.020 M AgNO3

c.

1.3 g of Zn added to 1.0 L of 0.040 M AgNO3

d.

2.6 g of Zn added to 1.0 L of 0.020 M AgNO3

e.

5.4 g of Zn added to 1.0 L of 0.020 M AgNO3

 

 

6. Calculate the amount of heat evolved in the complete oxidation of 8.17 g of Al at 25?C and 1 atm pressure. DHf? for Al2O3(s) is -1676 kJ/mol.

 

4Al(s) + 3O2(g) --> 2Al2O3(s)

a.

101 kJ

b.

127 kJ

c.

203 kJ

d.

237 kJ

e.

254 kJ



 

 

 

7. This question is concerned with heat change when ammonia is formed from its elements.

N2(g) + 3H2(g) --> 2NH3(g) DH = -92 kJ

Therefore, 92 kJ is the quantity of heat that is

a.

lost to the surroundings when 1 mole of hydrogen is consumed.

b.

lost to the surroundings when 1 mole of ammonia is formed.

c.

lost to the surroundings when 2 moles of ammonia are formed.

d.

gained from the surroundings when 1 mole of ammonia is formed.

e.

gained from the surroundings when 2 moles of ammonia are formed.



8. When two solutions are mixed, the container "feels hot." Thus

a.

heat is absorbed from the surroundings.

b.

the reaction is exothermic.

c.

the surroundings become colder.

d.

the heat of formation of the products is positive.

e.

the heat of formation of the reactants is positive.



9. What is the molar heat of combustion of ethanol, C2H5OH, if combustion of 2.00 g of ethanol causes a temperature rise of 3.29?C in a bomb calorimeter that has a heat capacity of 17.9 kJ/?C? The molecular weight of C2H5OH = 46.1.

a.

-2.56 kJ/mol

b.

-29.4 kJ/mol

c.

-58.9 kJ/mol

d.

-1360 kJ/mol

e.

-2720 kJ/mol



 

 

 

 

 

10. Given that
O(g) + e --> O-(g)      
DH = -142 kJ mol-1
O(g) + 2e --> O2-(g)      
D H = 702 kJ mol-1

the enthalpy change for the reaction represented by the equation
O-(g) + e --> O2-(g) is

a.

-844 kJ.

b.

-560 kJ.

c.

0 kJ.

d.

560 kJ.

e.

844 kJ.

 

 

11. Given the following data:

the heat for the reaction oxygen --> ozone at 298 K and 1 atm pressure in kJ is
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a.

-1405.

b.

-1263.

c.

-2668.

d.

-142.

e.

+142.


12. Given the following at 25C and 1.00 atm

 

Evaluate DH for the reaction below at 25?C:
Pb(s) + PbO2(s) + 2SO3(g) --> 2PbSO4(s)

a.

-3.77 x 103 kJ

b.

+3.77 x 103 kJ

c.

-639 kJ

d.

-521 kJ

e.

-769 kJ

13. Of the species listed below, the only one that has a standard enthalpy of formation value of zero is

a.

Na(l).

b.

Hg(l).

c.

Cl2(l).

d.

H2O(l).

e.

Ne(l).


14. Of the species listed below, the only one that has a standard enthalpy of formation value of zero is

 

a.

O(g).

b.

O2(l).

c.

O3(g).

d.

NH3(g).

e.

Na(s).



15. The standard heat of formation of sodium bromide, NaBr(s), corresponds to the reaction

a.

Na(g) + Br(l) --> NaBr(s).

b.

Na(g) + Br(g) --> NaBr(g).

c.

2Na(s) + Br2(l) --> 2NaBr(s).

d.

Na(s) + Br(l) --> NaBr(s).

e.

Na(s) + 1/2 Br2(l) --> NaBr(s)

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16. Which of the following is the correct thermochemical equation that represents the standard enthalpy of formation of CO(g)?

a.

C(g) + 1/2 O2(g) --> CO(g)

b.

C(s) + 1/2 O2(g) --> CO(g)

c.

C(g) + O(g) --> CO(g)

d.

CO(g) --> C(s) + 1/2 O2(g)

e.

1/2 C(s) + 1/2 CO2(g) --> CO(g)

 

 

17. For which of the following equations is the enthalpy change at 25?C and 1 atm equal to DHf (HCOOH(l))?

a.

CO2(g) + H2(g) --> HCOOH(l)

b.

CO(g) + H2O(l) --> HCOOH(l)

c.

C(s) + 2H(g) + 2 O(g) --> HCOOH(l)

d.

C(g) + 2H(g) + 2 O(g) --> HCOOH(l)

e.

C(s) + H2(g) + O2(g) --> HCOOH(l)



 

18. At 25?C when 1.00 g of calcium is burned at constant pressure in an atmosphere of oxygen to give CaO, 15.8 kJ of heat energy is liberated. The standard enthalpy of formation of CaO is ____________ kJ/mole.

a.

-15.8 x 1

b.

15.8 x 1

c.

-15.8 x 40.1

d.

15.8 x 40.1

e.

-15.8 x 56.1

 

 

 

19. 2Al(s) + 3O2(g) --> Al2O3(s)

 

At 25?C when 102 g of aluminum is burned at constant pressure in an atmosphere of oxygen to give Al2O3, 3150 kJ of heat energy is liberated. The standard enthalpy of formation of Al2O3 is

a.

b.

c.

-3150 x 102/27

d.

e.

-3150 x 27



20. The sign of DH for the process Br2(g) --> Br2(l) is

 

a.

positive and the process is endothermic.

b.

negative and the process is exothermic.

c.

negative and the process is endothermic.

d.

positive and the process is exothermic.

e.

may be positive or negative as it depends upon DHf Br2(l) and DHf for Br2(g).

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21. In a bomb calorimeter, reactions are carried out at

a.

1 atm pressure and 273 K.

b.

1 atm pressure and 298 K.

c.

constant pressure and 298 K.

d.

constant pressure only and the temperature will change.

e.

constant volume.



22. Which answer lists all the processes that are exothermic and none that are endothermic?

1. Sublimation of ice
2. Melting of ice
3.
Condensation of steam
4.
Freezing of water

a.

1 and 2 only

b.

2 and 3 only

c.

2 and 4 only

d.

3 and 4 only

e.

1 and 4 only

 

23. Which statement concerning the following is correct?
N2(g) + O2(g) + 181 kJ --> 2NO(g)

a.

The reaction is exothermic.

b.

The products have an enthalpy loss.

c.

The sign of DH for the reaction is positive.

d.

The products have less enthalpy than the reactants.

e.

The enthalpy of the reactants exceeds that of the products.


24. What is the change in enthalpy for the consumption of 1.00 mol of iron(II) oxide?

6 FeO(s) + O2(g) --> 2 Fe3O4(s) + 635 kJ

 

a.

-635 kJ

b.

-212 kJ

c.

-106 kJ

d.

106 kJ

e.

635 kJ



 

25. From the DHf data calculate the DH of reaction for

Fe2O3(s) + 3CO(g) --> 3CO2(g) + 2Fe(s)

 

a.

-1671 kJ

b.

-539 kJ

c.

+539 kJ

d.

+27.5 kJ

e.

-27.5 kJ

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