Create assignment, 54705, Quiz 6, Nov 27 at 9:12 am 1
This print-out should have 8 questions.
Multiple-choice questions may continue on
the next column or page – find all choices
before answering. The due time is Central
time.
Msci 15 0108
19:03, general, multiple choice, >1 min, .
001
If a system absorbs heat and also does work
on its surroundings, its energy
1. must increase.
2. must decrease.
3. must not change.
4. may either increase or decrease, depend-
ing on the relative amounts of heat absorbed
and work done. correct
Explanation:
∆E=q+w
q > 0 because heat is absorbed and w < 0 be-
cause the system does work on its surround-
ings. Therefore ∆E= (+) + (−). ∆Ecan
be positive only if q > w, and negative only if
w > q.
ChemPrin3e T06 14
19:03, general, multiple choice, <1 min, .
002
A system had 150 kJ of work done on it and
its internal energy increased by 60 kJ. How
much energy did the system gain or lose as
heat?
1. The system lost 90 kJ of energy as heat.
correct
2. The system lost 210 kJ of energy as heat.
3. The system gained 60 kJ of energy as
heat.
4. The system gained 90 kJ of energy as
heat.
5. The system gained 210 kJ of energy as
heat.
Explanation:
DAL Thermo Instability
20:06, general, multiple choice, >1 min, .
003
Consider the following compounds and
their thermodynamic data:
Compound ∆H◦
fS◦∆G◦
f
¡kJ
mol ¢ ¡ J
mol·K¢ ¡ kJ
mol ¢
CH4−75 186 −50
CH2O−108 218 −102
C6H5NH287 166 319
C2H452 68 219
Using this data, which of the following an-
swers includes the compounds that are ther-
modynamically unstable?
1. CH4, CH2O, C2H4
2. CH2O, C6H5NH2
3. CH4, C2H4
4. C6H5NH2, C2H4correct
5. Cannot be determined from the data pro-
vided.
6. All of the compounds are thermodynami-
cally stable.
Explanation:
ChemPrin3e T07 15
20:04, general, multiple choice, <1 min, .
004
The enthalpy of fusion of H2O(s) at its normal
melting point is 6.01 kJ ·mol−1. What is the
entropy change for freezing 1 mole of water at
this temperature?
1. +20.2 J ·K−1·mol−1
2. 0 J ·K−1·mol−1
3. −20.2 J ·K−1·mol−1
