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coralmonkeyMechanics

Oct 27, 2013 (3 years and 9 months ago)

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Chemistry B1B







Name:__________________

Exam IA



Date:_____________



Section:_________________


Circle the correct answer


1. Thermodynamics is applied to learn a reaction’s


[A] feasibility.


[B] mechanism.

[C] rate.

[D] stoichiometry.

[E] pathway.


2. Which of the following is (are) spontaneous process(es)?

1. Ice melting at 25°C

2. Heat flowing from a hot object to a cold object

3. An iron tool rusting


[A] 1 only

[B] 2 only

[C] 3 only

[D] 1 and 3 only

[E] 1, 2, and 3


3. A reaction must be sponta
neous at all temperatures when


[A]
is negative and
is positive.

[B]
is positive and
is positive.

[C]
is negative and
is negative.

[D]
is positive and
is negative.

[E]
is negative.


4. Which of the following would be expected to have the LARGEST entro
py value per mole?


[A] SO
3
(
g
)

[B] S
2
(
g
)

[C] SO
2
(
g
)

[D] S
8
(
g
)

[E] S(
g
)


5. Which symbol is used to represent the change of heat at constant pressure?


[A]

[B]

[C]

[D]

[E]


6. Which of the following reactions has the largest positive value of
per
mole of O
2
?


[A] 2C(
s
) + O
2
(
g
)

2CO(
g
)


[B] 2H
2
(
g
) + O
2
(
g
)

2H
2
O(
g
)

[C] C(
s
) + O
2
(
g
)

CO
2
(
g
)


[D] 2NO(
g
) + O
2
(
g
)

2NO
2
(
g
)

[E] 2Mg(
s
) + O
2
(
g
)

2MgO(
s
)


7. What is the thermodynamic quantity that provides the criterion for the spontaneity of a

chemical reaction?


[A]

[B]

[C]

[D]

[E]






8. If an ideal gas is expanded from 1.00 L to 5.00 L at constant temperature, then the following
must be true:


[A]
= 0 and
> 0.

[B]
> 0 and
< 0.

[C]
= 0 and
< 0.

[D]
> 0 and
> 0.

[E]
< 0 and
< 0.


9. All the following have free energy of formation values of zero EXCEPT


[A] U(
s
).

[B] H(
g
).

[C] Ni(
s
).

[D] He(
g
).

[E] Ca(
s
).


10.
and
are nearly the same in all the following processes EXCEPT


[A] C
6
H
6
(
s
)

C
6
H
6
(
l
).




[B] 3O
2
(
g
)

2O
3
(
g
).

[C] CH
4
(
g
) + Cl
2
(
g
)

CH
3
Cl(
g
) + HCl(
g
).

[D] CuO(
s
) + H
2
(
g
)

Cu(
s
) + H
2
O(
g
).

[E] F
2
(
g
) + H
2
(
g
)

2HF(
g
).


11. The total entropy of a system and its surroundings always increases for a spontaneous
process. This is a statement of


[A] the law of conservation

of matter.

[B] the first law of thermodynamics.

[C] the third law of thermodynamics.


[D] the second law of thermodynamics.

[E] the law of constant composition.


12. Which of the following must have a positive value for an endothermic reaction?


[A] Equil
ibrium constant

[B] Entropy change


[C] Electrode cell potential

[D] Free energy change

[E] Enthalpy change


13. The best criterion for the spontaneity of a chemical reaction is the sign of


[A]

[B]

[C]

[D]

[E]


14. For a reaction if
then


[A]

[B]

[C]

[D]

[E]


15. An ideal fuel for the control jet of a space vehicle should decompose with


[A]

[B]

[C]

[D]

[E]





16. In which of the following processes would one expect
to have the value closest to zero?


[A] CH
3
C(O)H(
g
) +
O
2
(
g
)


2CO
2
(
g
) + 2H
2
O(
g
)

[B] C
2
H
4
(
g
) + Br
2
(
l
)

C
2
H
4
Br
2
(
l
)


[C] 2NO(
g
) + O
2
(
g
)

2NO
2
(
g
)

[D] N
2
(
g
) + O
2
(
g
)

2NO(
g
)



[E] H
2
(
g
) + I
2
(
s
)

2HI(
g
)


17. Which of the following is true in the sublimation of one mole of dry ice?

1. The entropy decreases.

2
. The entropy increases.

3. The enthalpy increases.

4. The enthalpy decreases.


[A] 1 only

[B] 2 only

[C] 1 and 3 only

[D] 2 and 3 only

[E] 1 and 4 only


18. Which of the following processes involve an increase in entropy?

1. Br
2
(
l
)

Br
2
(
g
)

2. (NH
4
)
2
Cr
2
O
7
(
s
)

N
2
(
g
) + 4H
2
O(
l
) + Cr
2
O
3
(
s
)

3. 2KClO
3
(
s
)

2KCl(
s
) + 3O
2
(
g
)

4. 2HgO(
s
)

2Hg(
l
) + O
2
(
g
)


[A] 1 only

[B] 2 only

[C] 3 and 4 only

[D] 1, 3, and 4 only

[E] 1, 2, 3, and 4


19. What is equal to
at equilibrium?


[A]

[B]

[C]

[D]

[E]


20. T
he temperature of water decreases on the dissolution of NH
4
NO
3
. From this observation we
can conclude that the solution process would be best described as


[A] exothermic with a negative free energy change.

[B] exothermic with a negative entropy change.

[C
] endothermic with a positive entropy change.

[D] endothermic with a negative entropy change.

[E] exothermic with a positive entropy change.




Reference: [19.1.7]

[1] [A]



Reference: [19.1.15]

[2] [E]



Reference: [19.1.64]

[3] [A]



Reference: [19.1.20]

[4] [D]



Reference: [19.1.1]

[5] [B]



Reference: [19.1.34]

[6] [A]



Reference: [19.1.2]

[7] [C]



Reference: [19.1.19]

[8] [A]



Reference: [19.1.56]

[9] [B]



Reference: [19.1.11]

[10] [B]



Reference: [19.1.14]

[11] [D]



Reference: [19.1.6]

[12] [E]



Reference: [19.1.44]

[13] [C]



Reference: [19.1.79]

[14] [D]




Reference: [19.2.87]

[15] [E]



Reference: [19.1.25]

[16] [D]



Reference: [19.1.13]

[17] [D]



Reference: [19.1.29]

[18] [E]



Reference: [19.1.4]

[19] [A]



Reference: [19.1.54]

[20] [C]





























Solve the following problems. Show all your work. (All problems worth 5 points)


1.

Given that:


S(s) + O
2
(g)


SO
2

(g)



H =
-
295.8 kJ/mol





2SO
3

(g)


2 SO
2

(g) + O
2

(g)



H = +197.8 kJ/mol



Determine the enthalpy

change and the change in internal energy for the reaction:





2 S(s) + 3 O
2
(g)


2 SO
3
(g)

H = ???
















2.

Given the following information for the reaction that is carried out at 25
o
C, calculate

G
o

for the reaction at 25
o
C. Interpret

what the value of

G
o

is telling you.





2 A (g) + B (g)


C (g)


Substance


H
f
o

(kJ/mol)

S
o

(J/mol



A(g)

ㄹ1

㈴

B(g)

㜰⸸

㌰3

C(g)

-
ㄹ1

ㄶ1

















3.

A sample of an ideal gas is allowed to escape reversibly and isothermally into a va
cuum.
Which of the following statements is correct? Explain.



1.

w

= 0,

E = q = a positive number



2.

w

= P

V + V

P



3.

w

= P

V,

E = 0, q =
-
P

V and is a negative number



4.


E = 0, q =
-
w

= a positive number



5.

w

= 0, q = 0,

E = 0










4.

Wh
at is the free energy change,

G, when 1.0 mole of water is converted, at 100
o
C and 1
atm, to steam at 100
o
C and 1 atm in a reversible manner?



H
vap
(H
2
O) = 40.6 kJ/mole.
























5.

Calculate the solubility product (K
sp
) for Mg(OH)
2

at 25oC.

The

G
f
o

values are given in
the table.

Species

Mg
2+
(aq)

OH
-
(aq)

Mg(OH)
2
(s)


G
f
o

-
454.8

-
157.3

-
833.7





















6.

Is the reaction of magnesium carbonate decomposing to magnesium oxide and carbon
dioxide spontaneous at 1000
o
C? Values of

H
f
o
and S
o

are given in the table. (Extra
credit
-

At what temperature does this reaction become spontaneous?)






Species


g


(s)


2
(g)

Mg(OH)
2
(s)


H
f
o

(kJ/mol)

-
601.2

-
110.5

-
1111.7

S
o
(J/K)

26.9

213.7

65.9