Final Exam Review
Gas Laws
CHEMISTRY
2015
1. In order for Boyles Law to be applied, which of the following conditions of a gas must be held
constant? (the amount of gas is also held constant)
a) Pressure b) Temperature c) Volume d) all of these
2. Which of the following statements explains why the pressure inside a tire increases on a hot
day?
a)
b)
c)
d)
On hot days, air leaks into a tire instead of out.
The volume of the tire decreases, causing an increase in pressure
The heat causes the molecules of gas inside the tire to have higher energy collisions
Tire pressure will not increase on a hot day
3. Which theory did you use in answering question 14?
a) Big Bang Theory b) Kinetic Molecular Theory c) Evolutionary Theory d) Relativity Theory
4. The volume of 1 mole of any gas at STP is:
23
a) variable b) 6.02 x 10 liters c) 22.4 liters
d) 100 liters
5. As temperature of a liquid is increased, the liquid’s vapor pressure
a) decreases b) increases c) remains constant d) could do any of the above
6. If you collect 80.0 liters of nitrogen gas at STP, how many moles of gas will you have?
N=pv/rt 1*80/.0821*273 = 3.57 moles
7. A 6 liter sample of gas is at a pressure of 100 kPa. What will the pressure be if the volume is
decreased to 2 liters? ( the amount of gas and temperature do not change)
Pv=pv 6*100=2*P P= 300 kPa
8. The behavior of a real gas best approximates the behavior of an ideal gas under what
conditions?
a) low pressure and temperature
b) high pressure and temperature
c) high pressure and low temperature d) low pressure and reasonably high temperature
9. A 5 liter sample of gas is initially at a temperature of 20 °C (293K). What would its volume be if it
is heated to 300 °C (573K) at a constant pressure?
Charles V/T=V/T
5*573/293= V
9.78L
10. The instrument used to measure atmospheric pressure is called a
a) thermometer b) spectrometer c) barometer d) calorimeter
11. Liquid (or fluid) barometers usually contain which liquid?
a) water b) alcohol c) mercury d) sulfuric acid
ver 1 6/10/15
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Final Exam Review
Gas Laws
CHEMISTRY
2015
12. Which property of the liquid you picked in question 10 makes it the fluid of choice for
barometers?
a) its high density b) its low density c) its low toxicity d) its minimal effect on the environment
13. What Kelvin temperature is equal to –48° Celsius? K = C+ 273
225
14. Which of the following is the theoretical point at which all molecular motion ceases?
a) 273° C
b) 0 K
c) 100 K
d) –32° C
15. Which of the following is the correct expression for pressure:
a) force x acceleration b) distance/time c) mass/volume d) force/ area
16. Which of the following is a valid unit of pressure measurement?
a) PSI b) kilopascals c) atmospheres d) all of these
17. According to Avogadro’s Hypothesis, under the same conditions, equal volumes of gases have
the same
a) density b) number of molecules MOLES c) mass d)molecular mass
18. At a high elevation, a pot of water will boil at:
a) a lower temperature than at sea level
b) a higher temperature that at sea level
c) the same temperature as at sea level
d) water will only boil at sea level
19. A sample of gas under constant pressure undergoes a temperature change from 293K
to 303K. If the original volume was 1.5 liters, what is the final volume in liters?
Charles V/T= V/T 1.5*303/293= V
1.55 L
20. If 200 ml of methane undergoes a pressure change from 89 kPa to 99 kPa, under
constant temperature, what is the final volume in milliliters?
Boyle 89*200 = 99*V V= 89*200/99 179.8 ml
21. A sample of gas is kept at constant volume during an experiment. The temperature is
reduced from its initial value of 320 K to a final value of 303 K. If it has a final pressure of
757 torr, what was its initial pressure in torr?
PV/NT=R V and N constant so P/T=P/T P/320=757/303 P=320*757/303 = 799.47
Can keep pressure in torr as R is not part of calculation
22. If 0.08 moles of an ideal gas is at a pressure of 95 kPa with a temperature of 300K,
what is its volume in liters?
PV=nRT
95kPa *1/101.325= .94 ATM
V= nRT/P .08*.0821*300/.94 = 1.97L
ver 1 6/10/15
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Final Exam Review
Gas Laws
CHEMISTRY
2015
23. What is the final volume in milliliters of a gas that was initially at a pressure of 0.95
atm with a volume of 456 ml. The temperature was increased from 295 K to 300 K, which
resulted in a final pressure of 1.1 atm?
456ml = .456 L
PV/T = PV/T N does not change
.95*.456/295 = 1.1 * V / 300 V= 300*.95*.456/(295*1.1) = .400 L = 400 ml
24. Assume that 10.0 liter of air is near a thermonuclear explosion. This volume of air is
heated from 0 ° C to 546,000 ° C. Assuming expansion under constant pressure, what is
the new volume for this air in liters?
Charles V/T = V/T
10.0/273 = V/546,273 V = 10*546273/273 = 20,010 L
25. A sealed glass flask contains helium at a pressure of 720 mm Hg and a temperature of
25° C. The flask is packed in dry ice at a temperature of –73°C and the gas cools to this
temperature. What is the pressure?
P/T =P/T
720/298 = P/ 200 P = 200*720/298 = 483.22 mm Hg
No R so can keep mmHg
26. Calculate the pressure, in kPa, needed to compress 2.5 liters of gas initially at a
pressure of 92 kPa with a temperature of 20 ° C into a container with a volume of 0.10 liters
at a temperature of –150 ° C.
PV/T = PV/T no R can keep kPa but have to use K with –temp
92*2.5/293 = P*.10/123
P = 123*92*2.5/(.10*293) = 965.53 kPa
27. Calculate the volume at STP for a gas that is initially at a volume of 100 ml with a
pressure of 690 torr and a temperature of 0 ° C.
PV/T = PV/T no R can use torr use K 100ml = .1L STP is 1 atm 273 K
690* .1 /273 = 1*V/273 temp doesn’t change
690*.1= 1*V = 69 L
28. What is the temperature of 0.5 moles of an ideal gas that occupies a volume of 20 liters
with a pressure of 0.5 atm?
PV=NRT
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T= PV/NR
T= .5*20/.5*.0821 = 243.6 K
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Final Exam Review
ver 1 6/10/15
Gas Laws
CHEMISTRY
2015
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