Name:____________________ Per:______
Unit 5 Outline- Gas Laws and Kinetic Molecular Theory
Essential Skills/ State Standards:
1. Know the random motion of molecules and their collisions with a surface create the observable pressure on
that surface.
2. Know how the random motion of molecules explains the diffusion of gases.
3. Know the values and meanings of standard temperature and pressure (STP).
4. Know how to convert between the Celsius and Kelvin temperature scales.
5. Know there is no temperature lower than 0 Kelvin.
6. Know how to apply the gas laws to relations between the pressure, temperature, and volume of any amount of
an ideal gas or any mixture of ideal gases.
7. Know how to convert the mass of a molecular substance to volume of gas at standard temperature and
pressure.
*8. Students know how to solve problems by using the ideal gas law in the form PV = nRT.
Vocabulary
kinetic molecular theory
Barometer
Standard molar volume of a gas
mm Hg, kPa, torr, atm
Absolute zero
Ideal gas
Real gas
STP
Pressure
Ideal gas law
diffusion
Kelvin
Combined gas law
Phase Change
Melting
Sublimation
Freezing
deposition
Condensation
evaporation
Phase diagrams
Triple point
Critical point
Book Assignments
Topic
Read
Required Problems
1.
2.
3.
4.
Section 10-3 P. 313- 325
Section 11-1 p. 333-337
Section 11-2 p.340- 345
Section 12-3 p. 381- 382
Section Review 10-3 p. 325 #2-5
Chapter 11 Review p. 357 # 10, 11, 12
Chapter 11 Review p. 357 -358 # 16, 17
Section 12-3 Review p. 382 # 7 & 8
Combined Gas Laws
Molar Volume of Gases
Ideal Gas Law
Phase Changes/ Diagrams
Study Guide (Use notes, worksheets, and labs in addition to this study guide)
1.
Differentiate between the 3 phases of matter:
State of
Molecular Motion -how fast
Compressibility?
Matter
are they moving
(Fast, med, Slow)
Solid
Slow
None
Liquid
Med
Some
Gas
Fast
Lots
2. Identify the names of the phase changes in each direction:
melting
Strength of attraction (intermolecular
forces) between molecules
(Weak, Med, Strong)
Strong
Med
Weak
Vaporization
Liquid
Solid
freezing
Gas
Condensation
3. Generally, in what state (liquid, gas…) would polar substances be found at room temperature& why? Give an
example. Explain how non-polar substances compare?
Polar molecules (ex: H2O) have greater intermolecular attractions between molecules than non polar
substances (ex: (H2, O2, N2). Because of these attractions, polar molecules tend to want to “stick together”
and remain in the liquid state at room temperature at much higher temperatures than non-polar molecules.
Non-polar molecules are usually found as gases which have very little intermolecular attractions between
molecules. The elevated boiling point in polar substances compared to non-polar substances highlights this.
4. a. What does temperature actually measure in a substance?
Avg. kinetic energy (average speed)
b. What are water molecules doing at each of these temperatures: O ° F, O °C , O Kelvin (which is coldest?)
O K= coldest & molecules would not be moving,
O ° F= second coldest water would be frozen since it does
so at 32 ° F, O °C = water would be turning into a solid at this temperature.
c. What is “absolute zero”? Why is it significant?
It’s a theoretical point at which all molecular motion would cease. It never gets that cold.
5. Explain how the diffusion of gases occurs (on the molecular level)?
Gases move randomly and tend to spread out into open areas.
6. a. What is pressure? (you’ve got molecules in a container, explain what causes the pressure)
random motion of molecules and their collisions with a surface create the observable pressure on that surface.
b. What device measures pressure?
Barometer
c. Convert 500 mmHg into kPa
500 mmHg x 101 kPa
= 70 kPa
760 mmHg
7. In a sealed container, what happens to the pressure as the temperature increases? Explain on molecular level.
As temperature increases, gas particles collide with the inside of the container more frequently. This results in
an increase in pressure.
8. At Standard Temperature & Pressure (STP), the value for pressure is 1 atm & temperature is 0 °C (or 273K)
1 Mole of gas in these conditions will have a volume of 22.4L.
9. a. What does volume measure in an object?
3-D space an object occupies
b. What are some common units used to measure volume?
L, mL, cm3, m3
c. For the following ideal gases at STP, fill in the chart.
Gas
Volume (KNOWN Value)
Mass
# of Molecules
0.5 mole of H2 gas
11.2 L
1.01 g
3.01 x 1023
0.5 moles of CO2 gas
11.2 L
22 g
3.01 x 1023
d. If gases have different masses (sizes) how can they occupy the same volume at STP?
Gases are mostly empty space so their size (mass) is negligible in a container. Bigger ones will be slightly
closer together, but it makes no difference in terms of their behavior.
10. a. In what extreme conditions of temperature and pressure do “ideal” gases differ from “real” gases?
Under high pressure and low temperatures, molecules of gas are closer together, move slower, and start to
become attracted to each other. They start to behave more like liquids than gases.
b. According to the kinetic molecular theory, how do “ideal” gases differ from “real” gases (behaviorally)?
Ideal gases: are far apart, move rapidly, have elastic collisions, and are not attracted to the other particles.
Real gases are close, move more slowly, have inelastic collisions, and are attracted to each other (again, more
like liquids).
c. Which type of gas is most common (ideal or real). Explain.
Ideal gases are most common because we live in conditions of normal temperatures and pressures (vs. extreme)
For Calculations: Show formula & work
11. At standard temperature, a gas has a volume of 275 mL. The temperature is then increased to 130 ºC, and
the pressure is held constant. What is the new volume?
P1V1 = P2V2
= 406 mL
T1
T2
12. Given 44.8 L of N2 at STP, calculate moles of N2.
13. What volume will be taken up by 25g of CO2 at STP?
2 ways to solve:
Pv= nRT
or 44.8 L x 1 mol =
22.4 L
Step 1: convert to moles
2 moles
25 g CO2 x 1 mol = .57 moles
44.01 g
2 ways to solve: Pv= nRT or .57 moles x 22.4 L = 13 L
1 mole
14.
A sample of air has a volume of 140.0 mL at 67ºC & 200 Torr. At what temperature will its volume be
50.0 mL if the pressure is increased to 600 Torr?
P1V1 = P2V2
= 364 400 K
T1
T2
15. Using the phase diagram for CO2:
a. Under standard conditions, what phase would you find CO2 ?
( & show it on the diagram too with a big X & label)
Gas
X
b. CO2 can be a liquid, however, we only see it as a solid (dry ice) or gas. Using the diagram, explain
why we never see liquid CO2.
We are not at the correct temperature and pressure to see carbon dioxide as a liquid. We’d need to increase
the pressure and/ or drop the temperature.