Chapter 5: Thermochemistry
Supplemental Instruction
Iowa State University / Leader: / Danielle
Course: / Chem 177
Instructor: / Dutton
Date: / 02.20.19

Check-In Assessment

1.  Which substance contains Mn in a +7 oxidation state?

1.  MnO 2. KMnO4 3. MnO2 4. Mn2O7

a.  (1)

b.  (2)

c.  (3) and (4)

d.  (2) and (4)

2.  Which atom undergoes reduction in the following reaction?

2 Fe2O3 (s) + 3 CO (g) à 2 Fe (s) + 3 CO2 (g)

a.  Fe

b.  O

c.  C

d.  It is not redox reaction

3.  Give the appropriate term for each description of thermochemistry

joule (J) / calorie / system
closed system / open system / isolated system
surroundings / internal energy / heat
work / state function / path function

a.)  The portion we single out for study is called the ______.

b.)  The value of a ______depends only on the initial and final states of the system, not on the path the system took to reach that state.

c.)  The value of a ______depends on the path the system took to reach that state.

d.)  In thermodynamics, ______performed by a system is the energy transferred by the system to its ______.

e.)  The energy used to cause the temperature of an object to increase is ______.

f.)  The SI unit for energy is the ______.

g.)  A hot cup of coffee in a mug is an example of an ______.

h.)  A hot sandwich wrapped in plastic is an example of a ______.

i.)  Ice cold water in a hydro flask is an example of an ______.

j.)  ______is the amount of energy, usually in J, required for one gram mass of a substance to increase by 1 °C or K.

k.)  Change in ______of a system is defined by the equation ΔE=q+w.

4.  When a system loses heat to the surroundings, what do we call that process? What about when the system gains heat from the surroundings?

5.  A system releases 66.1 kJ of heat to its surroundings while the surroundings do 88.0 kJ of work on the system. Find its change in internal energy. Is this process exothermic or endothermic?

6.  The ΔE of a system that releases 14.4 J of heat and does 4.8 J of work on the surroundings is ______J.

a.  19.2 J

b.  14.4 J

c.  4.8 J

d.  - 19.2 J

7.  The value of ΔH for the reaction below is -72 kJ. How many kJ of heat will be released when 1.0 mol of HBr is formed in this reaction?

(recall the first law of thermodynamics which states: ΔEsys+ ΔEsurr=0)

H2 (g) + Br2 (g) à 2HBr (g)

a.  +144 kJ

b.  +72 kJ

c.  +36 kJ

d.  -36 kJ