FUNDAMENTALS
TEST DATE: ___________________
Name: __________________________ Period: ________
UNIT 7: Gas Laws Review Sheet KEY
1. Equations to Know:
a. Dalton’s Law: Ptotal = P1 + P2 + P3 …;
Total Pressure = Sum of the partial pressures and each pressure exerts a separate pressure independent of
the other gases
b. Boyle’s Law: P1 × V1 = P2 × V2
Volume and pressure of a gas are ___INDIRECTLY_______ proportional
c. Charles’ Law: V1 / T1 = V2 / T2
Volume and temperature of a gas are _____ DIRECTLY _____ proportional
d. Gay-Lussac’s Law: P1 / T1 = P2 / T2
Temperature and pressure of a gas are ______ DIRECTLY___ proportional
e. Ideal Gas Law: PV = nRT
P = Pressure, V = volume, n = number of moles, R = Universal Gas Constant, T= Temp in Kelvin
2. Definitions to Know
a. Three Common States of Matter in Terms of Particle Arrangement, Motion, Energy and Forces
Solid
Liquid
Gas
-Definite shape
-Takes shape of container
-Fills container
Description
-Definite volume
-No compressibility
-Very little motion
-Least energy
-Greatest intermolecular
forces
b.
c.
d.
e.
3.
4.
5.
6.
-Constant volume
-No compressibility
-Particles slide past each other
-Intermediate energy/forces
-Changeable volume
-Easily compressed
-Particles move freely
-Highest energy
-Weakest intermolecular
forces
Phase Changes (i.e., melting, freezing, etc.) Changes between states of matter
Pressure (also know the different units for pressure) Force per unit area (mmHg, kPa, atm, torr)
Heat A form of thermal energy that is present in all matter (measured in Joules or calories)
Temperature (also know the two units discussed in class) Measure of the average kinetic energy of
the particles in a substance (°C-Celsius; K-Kelvin)
f. Absolute Zero 0K or -273°C, the temperature where all molecular motion stops
What does STP stand for and what are its numerical values? Standard Temperature and Pressure
Pressure units are 1 atm
Temperature units are 0°C and 273 K
What are the three assumptions of the Kinetic Theory?
(A) All matter consists of small particles
(B) These particles are in constant motion
(C) Collisions between particles are perfectly elastic
What are the assumptions of Ideal Gases?
(A) Obeys all of the gas laws under all conditions
(B) Does not condense into a liquid when cooled
(C) Shows perfectly straight lines when its V and T & P and T relationships are plotted on a graph
Be able to label the phases/phase changes on a diagram similar to the one below:
7. Know the boiling point and freezing point of water. B.P. = 100°C and F.P. = 0°C
8. If given a phase diagram like the one below, be able to identify when melting and freezing occur and answer the
following the questions.
Gas
Liquid
Solid
a. What is the melting temperature of the substance? 5°C
b. What is the boiling temperature of the substance?
15°C
c. What is happening to the temperature at a, c and e?
Temperature is increasing
d. What is happening at points b and d? Phase change
e. Label solid, liquid and gas on the curve.
f. On which point of the curve are the particles moving
the least? A
g. Where on the curve is ONLY a liquid present? C
GAS LAW PROBLEMS
1. Convert the following temperatures from Celsius to Kelvin and Kelvin to Celsius:
a. 22°C 295 K
d. 220 K -53°C
b. 444°C 717 K
e. 390 K 117°C
c. -60°C 213 K
f. 20 K -253°C
DALTON’S LAW
2. There is a mixture of three gases in a closed container. Gas A exerts a pressure of 15 psi, Gas B a pressure of 6.5
psi, and the total pressure is 25.7 psi. What is the partial pressure of Gas C? PC = 4.2 psi
BOYLE’S LAW
3. A gas occupies a volume of 100 cubic meters at 2.5 atm. What volume will it occupy at a pressure of 1.25 atm if
the temperature remains constant? V2 = 200 cm3
4. A gas occupies a volume of 500 cm3 at 150 kPa. What volume will it occupy at 101.3 kPa if the temperature
remains constant? V2 = 740.4 cm3
5. The pressure of a sample of helium in a 2.00L container is 2.5 atm. What is the new pressure if the sample is
placed in a 6.00L container? P2 =.833 atm
CHARLES’ LAW
6. A gas occupies a volume of 5340 cm3 at a temperature of 20°C. Calculate the volume that this gas will occupy at
60°C if the pressure is held constant (must convert to Kelvin first). V2 = 6069 cm3
7. A balloon full of air has a volume of 2.75 L at a temperature of 18°C. What is the balloon's volume at 45°C?
V2 = 3.01 L
8. A gas is at 33°C and a volume of 120 mL. What is the temperature if the volume is changed to 150 mL?
T2 = 382.5 K
GAY-LUSSACS’ LAW
9. A gas has a pressure of 3 atm and a temperature of 273 K. If the temperature increases to 546 K, what is the new
pressure if the volume remains constant? P2 = 6 atm
10. At 315K a gas exerts a pressure on its container of 101.67 kPa. The temperature suddenly drops to 280K, what
pressure does the gas now exert? P2 = 90.37 kPa
11. At what temperature will chlorine, originally at a pressure of 0.018 atm at 169K, exert at a pressure of 0.396 atm?
P2 = 3718 K
IDEAL GAS LAW
“R” Constants: 0.0821 L•atm/M•K (For atm)
8.315 L•KPa/M•K (For kPa)
62.4 L•mmHg/M•K (For mmHg)
12. Calculate the temperature of a gas if 4.5 moles of it occupies a volume of 1.85 L at 1.23 atm (HINT: use “R” for
atm) n = 6.16 K
13. Calculate the pressure in kPa exerted by a gas if .83 moles occupies 8.5 L at 150 K. (HINT: use “R” for kPa)
P = 121.8 KPa
14. If I have an unknown quantity of gas at a pressure of 1.2 atm, a volume of 31 liters, and a temperature of 87°C,
how many moles of gas do I have? (HINT: use “R” for atm) n = 1.26 moles
ABSOLUTE ZERO VIDEO QUESTIONS
15. What modern conveniences exist today because of cold? Refrigerators, air conditioning, MRI
16. Why were oxygen, nitrogen, and hydrogen called permanent gases? They do not liquefy
17. Why did Dewar give up on trying to liquefy helium? There was a limit to how much he could obtain
18. What new word was developed for the phenomenon when all resistance to the flow of electricity stops at very,
very cold temperatures? Superconductivity
19. What new state of matter was proposed by Einstein to explain the strange superfluid properties of helium at two
degrees above absolute zero? Bose-Einstein Condensate
20. Why does it seem unlikely that we’ll ever be able to reach absolute zero? Too difficult, an apparatus would
need to be the size of universe and it would take the age of universe to achieve absolute zero