Enthalpy Multiple Choice Test
Click in the appropriate box for each question, then click "Done" at the bottom.
10 marks for each correct answer. Hints cost 5 marks each.


1. An endothermic reaction:
Will not proceed     Releases heat to the surroundings   Absorbs heat from the surroundings     
Releases free energy     Has a negative value of DH

2. An exothermic reaction:
Absorbs heat     Will always be fast       Will always be slow     
Absorbs free energy     Has a negative value of DH

3. Compare the reaction CuO(s) + CO2(g) ® CuCO3(s) with the reaction system:
CuO(s) ® Cu(s) + 1/2 O2(g)
CO2(g) ® C(s) + O2(g)
Cu(s) + C(s) + 3/2 O2(g) ® CuCO3(s)
Which of the following is true?

Thermodynamically, the reaction is different from the reaction system
The reaction will occur faster than the reaction system
The reaction will have a much greater DH than the overall DH of the reaction system
The DH of the reaction is the same as the DH of the overall system
None of these

4. The internal energy of a system can change because:
Heat can flow into the system
Heat can flow out of the system
The system can do work on the suroundings
The surroundings can do work on the system
All of the above

5. When ammonium chloride, NH4Cl(s), is dissolved in water, the water temperature drops.
Which of the following statements is true?
The products contain more heat than the reactants
The reaction is exothermic
The value of q for the surroundings is positive
The internal energy of the system decreases
None of the above

6.  A certain reaction has a positive value of DH. Which of the following is true?
The reaction can not be spontaneous
The reaction will always be spontaneous
Heat will be released by the reaction
The reaction will proceed if the entropy decreases
The reaction might proceed if the entropy increases
7.  For the reaction 2 SO2(g) + O2(g) ® 2 SO3(g), which of the following is the correct 
     expression for evaluating the reaction enthalpy?
DH = DHof (SO2(g)) + DHof (O2(g)) + DHof (SO3(g)) 
DH = 2 DHof (SO2(g)) + DHof (O2(g)) + 2 DHof (SO3(g))      
DH = 2 DHof (SO3(g)) - DHof (O2(g)) + 2 DHof (SO2(g))      
DH = 2 DHof (SO3(g)) - DHof (O2(g)) - 2 DDHof (SO2(g))      
DH = - 2 DHof (SO3(g)) + DHof (O2(g)) + 2 DHof (SO2(g))      


8. The enthalpy of formation of Na(s) is: 
Negative    Positive     Zero     Unknown  

9. The superscript o in the term DHof  means:
The reaction is carried out at zero degress Celcius.
The reaction is carried out at zero pressure.
The enthalpy of reaction is zero.
The reaction is carried out at standard conditions. 
None of the above

10. The subscript f in the term DHof  means:
Formation of the compound from the elements.
Fluorine
Fairly big
Fairly small
Something impolite