include sign)
w = J
q = J
(
include sign)
w = J
6
8
6
2
CHEM_230_W16_PREP_E1
p 28
67) (
30 pts
) Two identical, rigid containers (A and B) are connected by
a valve. The valve is currently closed. Container A on the left
contains 1 mole of CO gas at 250K and container B on the right
contains 1 mole of N
2
gas at 300K. Assume that the gases act ideally
unless otherwise stated.
(
In each box below circle the one best answer.
)
A
1 mol CO
(MW = 28)
B
1 mol N
2
(MW = 28)
a) Which container contains more atoms?
Container A Container B Neither
b) Which container has the greatest gas density?
Container A Container B Neither
c) Which container has the molecules with the higher v
rms
?
Container A Container B Neither
i) The nitrogen gas in container B was cooled to 250K before the valve was opened. After the valve
was opened the total pressure in Container A
is (
Circle one
)
higher lower the same as
the
pressure in Container A before the valve was opened.
d) Which gas will require more energy to raise its temperature by 10 K?
CO N
2
Neither
f) In reality, which gas acts most ideally at a high pressure of 1000 atm?
CO N
2
they act similarly
e) Which gas has the highest compression factor "Z" at a moderate pressure of 200 atm when
compared at the same temperature?
Briefly explain your answer addresing one or both van der Waals factors:
g) What is the sign of the entropy change of the system when the valve is opened?
S > 0 S = 0 S < 0
h) What is the sign of q for the N
2
gas when the valve is opened?
q > 0 q = 0 q < 0
250K
300K
CO N
2
not enough information
3
3
3
3
3
3
3
3
6
CHEM_230_W16_PREP_E1
p 29
71) For the following questions (a-i), consider the two Scenarios X and Y.
0.5 mol of helium is sealed in a container
with a fixed volume of 6L at an initial
pressure of 2 atm. The container of helium
is initially at 20
o
C and is heated to 250
o
C.
Scenario X
Scenario Y
0.5 mol of helium is sealed in a flexible
container with an initial volume of 6 L and a
pressure of 2atm. The container of helium
is initially at 20
o
C and is heated to 250
o
C.
a) What is the sign of work for Scenario X?
(Circle one) + - 0 cannot be determined
b) What is the sign of work for Scenario Y?
(Circle one) + - 0 cannot be determined
c) Fill in the box with
< , > , = , or X
(for cannot be determined)
q for Scenario X
q for Scenario Y
d) Fill in the box with
< , > , = , or X
(for cannot be determined)
U for Scenario X
U for Scenario Y
e) Fill in the box with
< , > , = , or X
(for cannot be determined)
S for Scenario X
S for Scenario Y
f) Fill in the box with
< , > , = , or X
(for cannot be determined)
The density in container X
when it reaches 250
o
C
The density in container Y
when it reaches 250
o
C
h) Fill in the box with
< , > , = , or X
(for cannot be determined)
The v
rms
in container X when it
reaches 250
o
C
The v
rms
in container Y when it
reaches 250
o
C
g) Fill in the box with
< , > , = , or X
(for cannot be determined)
The collision frequency in
container X when it reaches 250
o
C
The collision frequency in
container Y when it reaches
250
o
C
i) Consider Container Y at 250
o
C as the initial state. The contents of Container X at 250
o
C are
added to Container Y. As as result of the addition of all of the molecules from container X, which of
