Sample Quiz

OC CHEM 120                  Quiz#3             Fall 2007                ZHOU

 

Student Name __________________________                    Date ________________

1. For the following process, calculate the change in DE of the system and determine whether the process if exothermic or endothermic:

A system absorbs 85 kJ of heat from its surroundings while doing 29 kJ of work on the surroundings;

 

2. The complete combustion of acetic acid, HC2H3O2 (l), to form water (l) and carbon dioxide (g) at constant pressure releases 871.7 kJ of heat per mole of HC2H3O2. (a) Write the balanced thermochemical equation for this reaction. (b) Draw the enthalpy diagram for the reaction.

 

 

 

3. Consider the following reaction: is the reaction endothermic or exothermic?

2 Mg (s) + O2 (g) --> 2 MgO (s)    DH = -1204 kJ

How many grams of MgO are produced during an enthalpy change of –96.0 kJ?

 

 

 

4. From the enthalpy of reactions: H2 (g) + F2 (g) --> 2 HF (g)    DH = -537 kJ
C (s) + 2 F2 (g) --> CF4 (g)    DH = -680 kJ
2 C (s) + 2 H2 (g) --> C2H4 (g)    DH = +52.3 kJ

calculate DH for the following reaction:
C2H4 (g) + 6 F2 (g) --> 2 CF4 (g) + 4 HF (g)