leazenby (jl35875) – Homework 1 – Sutcliffe – (52440)
1
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print-out
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have
18
questions.
Multiple-choice questions may continue on
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before answering.
001
10.0 points
If the reaction quotient
Q
for some hypothet-
ical reaction is 100, how does Δ
G
compare to
Δ
G
0
?
1.
Δ
G >
Δ
G
0
correct
2.
Δ
G <
Δ
G
0
3.
Δ
G
= Δ
G
0
4.
There is insufficient information given to
determine the answer.
Explanation:
Δ
G
= Δ
G
0
+
RT
ln
Q
If Q = 100, then the natural log term will be
positive.
This means that the non standard
value of Δ
G
will be bigger (more positive)
than the value of Δ
G
0
.
002
10.0 points
If Δ
G
◦
= 27
.
1 kJ at 25
◦
C for the reaction
CH
3
COOH(aq) + H
2
O(
ℓ
)
→
CH
3
COO
−
(aq) + H
3
O
+
(aq)
,
calculate
K
a
for this reaction at 298 K.
1.
1
.
78
×
10
−
5
correct
2.
1.01
3.
5
.
63
×
10
4
4.
9
.
89
×
10
−
1
5.
1
.
15
×
10
−
11
Explanation:
003
10.0 points
WITHDRAWN
004
10.0 points
The standard state for phosphorus is white
phosphorus.
(There’s a red form too, but
thats not the standard).
What is the numerical value of the equi-
librium constant
K
p
at 25
◦
C for the de-
composition of phosgine (PH
3
) gas into the
elements white phosphorus and hydrogen?
Δ
G
0
f
= 13
.
4 kJ
/
mol for PH
3
(g).
1.
None of these
2.
4
.
48
×
10
−
3
3.
1
.
00
×
10
1
4.
2
.
23
×
10
2
correct
5.
9
.
95
×
10
−
1
Explanation:
Δ
G
=
-
13
.
4 kJ
/
mol =
-
13400 J
/
mol
T
= 25
◦
C = 298 K
R
= 8
.
314
J
mol
·
K
K
p
=
e
−
Δ
G/
(
RT
)
= exp
bracketleftBigg
13400 J
/
mol
(8
.
314
J
mol
·
K
) (298 K)
bracketrightBigg
= 223
.
301
005
10.0 points
A group who investigated the formation of
ammonia from its elements determined that
K
c
is 90 at 773 K and 3 at 873 K. Is this
reaction endothermic or exothermic?
1.
exothermic
correct
2.
Cannot tell; insufficient information is
given.
3.
Neither; the reaction is at equilibrium.
4.
endothermic
Explanation:
The
K
is observed to decrease with increas-
ing temperature of reaction, which is charac-
teristic of exothermic reactions.
006
10.0 points
Which of the following reactions’ equilibrium
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leazenby (jl35875) – Homework 1 – Sutcliffe – (52440)
2
constants (K) would exhibit the greatest tem-
perature dependence?

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- Spring '08
- wandelt
- Chemistry, Reaction, Vapor pressure, Torr
-
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