CHM 2045C Module Seven Sample Exam
Multiple Choice Answers
1. The
correct answer is:
specific heat.
Explanation:
This is the definition of specific heat.
Solution Reference:
Page 245, Specific Heat
2. The
correct answer is:
Lead
Explanation:
Which metal has the smallest specific heat?
Solution Reference:
Page 245, Specific Heat
3.
The correct answer is:
1.73 J/g·?C
Explanation:
Solution Reference:
Page 245, Specific
Heat
4. The
correct answer is:
27.6?C
Explanation:
Solution Reference:
Page 245, Specific Heat
5. The
correct answer is:
-57,300 J
Explanation:
Solution Reference:
Page 245, Thermal Energy Transfer
6. The
correct answer is:
254 kJ
Explanation:
Solution Reference:
Page 261, Enthalpy Changes for Chemical
Reactions
7. The
correct answer is:
lost to the surroundings when 2 moles
of ammonia are formed.
Explanation:
The reaction is exothermic and the heat lost
is for the thermochemical equation that is written.
Solution Reference:
Page 261, Enthalpy Changes for Chemical Reactions
8. The
correct answer is:
the reaction is exothermic.
Explanation:
Heat is evolved by the reaction, as the
products are of higher energy than the reactants. The heat evolved is absorbed
by the solution so that the reaction system has a higher temperature.
Solution Reference:
Page 261, Enthalpy Changes for Chemical
Reactions
9. The
correct answer is:
-1360 kJ/mol
Explanation:
Solution Reference:
Page 255, Enthalpy
10. The
correct answer is:
844 kJ.
Explanation:
Solution Reference:
Page 263, Hess's Law
11. The
correct answer is:
+142.
Explanation:
Solution Reference:
Page 263, Hess's Law
12. The
correct answer is:
-769 kJ
Explanation:
Solution Reference:
Page 263, Hess's Law
13. The
correct answer is:
Hg(l).
Explanation:
Which element is in its most stable form at
25?C?
Solution Reference:
Page 268, Standard Enthalpies of Formation
14. The
correct answer is:
Na(s).
Explanation:
Which element is in its most stable form at
25?C? Compounds do not have DHf° values of zero.
Solution Reference:
Page 268, Standard Enthalpies of Formation
15. The
correct answer is:
Na(s) + 1/2 Br2(l)
--> NaBr(s)
Explanation:
Na is a solid at 25?C and Br2 is a
diatomic molecule and a liquid at 25?C. The standard heat of formation is the
change in heat for producing one mole of product from the reactants in their
most stable form at 25?C.
Solution Reference:
Page 268, Standard Enthalpies of Formation
16. The
correct answer is:
C(s) + 1/2 O2(g) -->
CO(g)
Explanation:
The standard enthalpy of formation of a
product involves the reaction of the elements in their most stable states (DHf° = 0
for the elements) to form the product. Response (a) is not the answer because
carbon is a solid at room temperature not a gas.
Solution Reference:
Page 268, Standard Enthalpies of Formation
17. The
correct answer is:
C(s) + H2(g) + O2(g)
--> HCOOH(l)
Explanation:
Carbon is a solid; hydrogen and oxygen are
diatomic gases at 25?C.
Solution Reference:
Page 268, Standard Enthalpies of Formation
18. The
correct answer is:
-15.8 x 40.1
Explanation:
Ca(s) + 1/2 O2(g) --> CaO(s)
To form one mole of CaO, 40.1 g of Ca need to be
burned.
Solution Reference:
Page 268, Standard Enthalpies of Formation
19. The
correct answer is:
Explanation:
Solution Reference:
Page 273, Determining Enthalpies of Reaction
20. The
correct answer is:
negative and the process is exothermic.
Solution Reference:
Page 252, Energy and Changes of State
21. The
correct answer is:
constant volume.
Explanation:
The heat, qv,
is measured in a bomb calorimeter and no change in volume takes place.
Solution Reference:
Page 273, Determining Enthalpies of Reaction
22. The
correct answer is:
3 and 4 only
Explanation:
The production of steam is endothermic, so the
reverse process would be exothermic. Likewise the melting of ice is
endothermic, so the reverse process would be exothermic.
Solution Reference:
Page 252, Energy and Changes of State
23. The
correct answer is:
The sign of DH for
the reaction is positive.
Explanation:
This is an endothermic reaction.
Solution Reference:
Page 261, Enthalpy Changes for Chemical
Reactions
24. The
correct answer is:
-106 kJ
Explanation:
Solution Reference:
Page 261, Enthalpy Changes for Chemical
Reactions
25. The
correct answer is:
-27.5 kJ
Explanation:
Solution Reference:
Page 261, Enthalpy Changes for Chemical
Reactions