Chapter 10 - Gases
Homework
is worth 20 points
The
answers follow the questions (except for Celsius to Kelvin conversions)
Kelvin to Celsius
Conversions (and vice versa):
1. Convert the following
values. If in Kelvin, convert to
Celsius. If in Celsius, convert to K.
a 56K d 37oC g -50oC
b 800K e
100oC h 0oC
c 298K f
25oC I -250oC
Barometers: Remember, Barometers are just a “closed”
manometer
2. A closed manometer (in
other words, a barometer) is filled with Hg and is connected to a container of
N2 gas. The difference in
the height of the Hg in the two arms is 270 mm. What is the pressure of the N2 in kPa? 36.0 kPa
3. A closed manometer is
filled with Hg and connected to a container of O2 gas. The difference in the height of the Hg in
the two arms is 691 mm. What Is the
pressure of the Oxygen in kPa?
92.12 kPa
4. Convert the pressure
answer (from question #3) from kPa to atmospheres. 0.91 atm
5. A barometer is filled
with Hg and connected to a container of Helium gas. If the pressure of the gas is 2.00 atm, what would the difference
in the height of Hg in the two arms be?
1520 mm Hg
6. A barometer is filled
with Hg and is connected to a container of Chlorine gas. If the pressure of the gas is 88 torr, what
would the difference in the height of the Hg in the two arms be? 88mm
7. A barometer is filled
with Hg and is connected to a container of Oxygen gas. If the difference in the height of the Hg in
the two arms is 345 mm, what would the pressure be in psi? 6.67 psi
Manometers: Remember, a manometer is an open ended
barometer
8. An open manometer is
filled with Hg and is connected to a container of H2 gas. The level of Hg is 29 mm higher on the side connected
to the outside air. What is the
pressure of the H2 gas in kPa if the outside air pressure is 101.3
kPa? 105.2 kPa
9. An open manometer is
filled with Hg and is connected to a container of H2 gas. The level of Hg is 6 mm higher on the side connected
to the container of gas. What is
the pressure of the H2 gas
in kPa if the outside air pressure is 101.3 kPa? 100.5 kPa
10. An open manometer is
filled with Hg and is connected to a container of Oxygen gas. The level of Hg is 25 mm higher on the side connected
with the outside air. If the pressure
of the gas in the container is 15 psi, then what is the pressure of the outside
air? 14.52 psi
11. An open manometer is
filled with Hg and is connected to a container of Methane gas. The level of Hg is 55 mm higher on the side connected
with the container of Methane. If
the Methane’s pressure is 770 torr, what is the pressure of the outside
air? 825 torr
Dalton’s Law of
Partial Pressure: Assume I am asking
for kPa unless otherwise stated
See Table A-8 onp.
899 for Water Vapor Pressure based on Temperature
12. A gas is collected
over water at 20oC. The
total pressure of the water vapor and gas combined is 97.2 kPa. What is the partial pressure of the
gas? 94.9 kPa
13. A gas is collected
over water at 10oC. The
total pressure of the water vapor and gas combined is 1 atm. What is the partial pressure of the gas in
atms? 0.99 atm
14. A gas is collected over water at 25oC. The total pressure of the water vapor and gas combined is 2 atm. What is the partial pressure of the gas in atms? 1.97 atm
15. A gas is collected over water at an unknown temperature. The total pressure of the water vapor and the gas combined is 93.83 kPa. If the partial pressure of the gas itself is 93.22 kPa, then at what temperature was this gas collected? 0oC
Charles’ Law: You can assume that pressure is constant in
each of these probs.
16. A balloon filled with
hydrogen gas has a volume of 400 cm3 and is at room temperature (25oC). What is the volume of the balloon if it is
at standard temperature – remember that standard temp is 0oC.(assuming
that pressure remains constant) 366 mL
17. A balloon filled with
helium gas has a volume of 150 cm3 and is at room temperature (25oC). What temperature is required to make the
balloon increase in size to 715 cm3? (assuming the pressure remains constant) answer in Kelvins. 1420 K
18. A balloon filled with
Nitrogen gas has a volume of 450 mL and is at –25oC. If the temperature were increased to 25oC,
what would its new volume be? 540 mL
19. A balloon filled with
Methane gas has an unknown volume at 35oC. But when the temperature was dropped to 0oC, the
balloon shrunk to 600 mL. What was the
original volume of the balloon? 677 mL
20. A balloon filled with Methane
gas has an unknown initial temperature, but was originally 560 mL in
volume. The temperature is changed to
–50oC and the new volume is 100 mL.
What was the original temperature on this balloon? 1249 K
Boyle’s Law: You can assume that temperature is constant
in each of these probs.
21. A container at a constant temperature has a volume of 870 cm3 under a pressure of 125 kPa. What pressure is necessary to make the container become 240 cm3 in volume? 453 kPa
22. A container at a constant
temperature has a volume of 280 cm3 under a pressure of 95 kPa. What will be the volume of the container if
the pressure changes to 50 kPa? 532 cm3
23. A balloon has a volume
of 500 mL under a pressure of 101 kPa.
If the pressure is dropped to 5 kPa, what will its new volume be? 10100 mL
24. A balloon has an
unknown initial volume at a pressure of 80 kPa. If the pressure is increased to 150 kPa and the balloon shrinks
to 50 mL, how big was it in the first place? 94 mL
Dalton’s and Boyle’s
Laws combined: First find the partial
pressure of just the gas. Then, use the
partial pressure of just the gas (not the water vapor) to determine a
new volume according to the pressure change indicated in the problem.
25. 872 cm3 of
a gas was collected over water at 25oC. The total pressure of the water and the gas together is 98.5
kPa. What would the volume of the gas
(and just the gas – not the water vapor) be under standard pressure? (of course
you must assume that the temperature remains constant. And you must know that standard pressure is
1 atm) 820 mL
26. 20 cm3 of a
gas was collected over water at 25oC. The total pressure of the water and the gas together is 98.5
kPa. What would the volume of the gas
be if the pressure was reduced to 90.0 kPa?
(assuming that the temperature remains constant) 21.2 mL