STATES OF
MATTER
Chapter 10
Three States of Matter
State of
Matter
Gas
Liquid
Solid
Volume
Shape
Density
Compressibility
Motion of
Molecules
Phase Diagrams
• phase diagram: graph that shows the
relationship between the physical state of a
substance and the temperature and pressure
of the substance.
THREE IMPORANT LINES
Liquid-gas phase changes:
 Liquid-solid phase changes:
 Solid-gas phase changes:

TWO IMPORTANT POINTS
 Triple
Point:
where all three lines meet, a specific temperature
and pressure where all three phases exist at the
same time
TRIPLE POINT VIDEO
TWO IMPORTANT POINTS
 Critical
Point:
a specific temperature and pressure where the gas
can no longer be turned into a liquid, above this
point a substance becomes a supercritical fluid
“NORMAL” CONDITIONS

Occur at standard atmospheric pressure: 1 atm or 101.3 kPa
 To identify the normal boiling point of a substance: Locate the
line between liquid and gas, and identify the temperature at 101
kPa __________________

To identify the normal freezing point of a substance: Locate the
line between liquid and solid, and identify the temperature at 101
kPa __________________
GASES
Chapter 11
WHAT ELEMENTS EXIST AS A GAS AT ROOM
TEMPERATURE?
H2 N2 O2 F2 Cl2 He Ne Ar Kr Xe Rn
KINETIC MOLECULAR THEORY OF GASES
Describing the _____________
of the
motion
molecules
______________________
of a gas.
 Ideal gas: hypothetical gas that satisfies all 5 ideas of KMT


1.
2.
Occurs at high temp and low pressure
A gas consists of very small particles, each of which has
mass
a ____________.
volume
The ____________or
dimensions of gas particles are
zero
considered to be __________
because of the large space
between each particle.
KMT CONT.
3.
4.
5.
constant, rapid motion
Gas molecules are in _______________________
in random directions.
Collisions among molecules or with the walls of their
elastic
container are perfectly ____________.
Gas
molecules do not show attractive or repulsive forces
on one another.
temperature they will
If gases are at the same ______________,
kinetic
have the same ______________energy.
1. Gases have very low densities.
• Solids and liquids have much higher density.
• Gas particles are spread out.
2. Gases have mass.
• A filled balloon is heavier than an
empty balloon.
3. Gases are the most compressible state of
matter.
• Gas particles can be squished closer
together.
4. Gases take the shape and
volume of their containers.
• Gases fill the entire space
they are in.
5. Different gases will mix evenly and completely
called diffusion.
• You can smell brownies baking in the oven
when in a different room.
6. Gases exert pressure.
• You can feel the wind hit your face.
7. The pressure of a gas depends on its
temperature.
• Temperature is a measure of kinetic energy.
The more energy, the more force the gases
hit a surface, the higher the pressure.
GAS MEASUREMENTS
MEASURING GASES
Measurement
Symbol
Unit
Abbrev.
Amount
n
moles
mol
Volume
V
Liters
L
Temperature
T
Kelvin
K
Pressure
P
atmosphere
atm
REMEMBER:
1 mol = 6.02 x 1023 particles
1 mL = 1 cm3
K = oC + 273
K = 0C + 273
0 K = ___0C
273 K = ___0C
373 K = ___ 0C
absolute zero
freezing pt of water
boiling pt of water
____ K = 250C
____ K = 370C
room temperature
body temperature
What temp would a gas be:
in a boiling water bath?
in an ice bath?
WHAT IS PRESSURE?

Force exerted on a certain area
Same Force
Less Area
More Pressure

For gases:
pressure is measured by the number of collisions
the particles have with each other and the walls of
the container
Units of Pressure
Measuring Gas Pressure
• Atmospheric pressure is
measured by a barometer.
760 mm
• The pressure is then read on
the column of mercury.
Barometer
Measuring Gas Pressure
• At sea level, the atmosphere keeps the
mercury in a barometer at an average height
of 760 mm (equals 1 atmosphere, atm.)
• One millimeter of mercury is also equal to a
torr, after Evangelista Torricelli, the Italian
physicist who invented the barometer.
Measuring Gases
10 miles
4 miles
Sea level
0.2 atm
0.5 atm
1 atm
• Scientists have specified a set of standard
conditions called standard temperature
and pressure (STP)
Standard Temp =
0°C = 273 K
Standard Pressure =
1 atm = 760 mmHg = 760 torr = 101.3 kPa
PRESSURE CONVERSIONS
The average atmospheric pressure in Denver,
Colorado is 0.830 atm. Express this pressure in:
a. millimeters of mercury (mm Hg) and
b. kilopascals (kPa)
Given: atmospheric pressure = 0.830 atm
Unknown: a. pressure in mm Hg
b. pressure in kPa
PRESSURE CONVERSIONS ANSWERS
A)
760 mm Hg
atm  mm Hg; atm 
 mm Hg
atm
760 mm Hg
0.830 atm 
 631 mm Hg
atm
B)
101.325 kPa
atm  kPa; atm 
 kPa
atm
101.325 kPa
0.830 atm 
 84.1 kPa
atm
THE GAS LAWS
WHAT IS VAPOR PRESSURE?

The pressure that exists above the surface of a
liquid from particles escaping the surface of the
liquid
VAPOR PRESSURE IS EFFECTED BY HOW
VOLATILE THE LIQUID IS
DALTON’S LAW OF PARTIAL PRESSURES
 John Dalton discovered that the pressure exerted by
each gas in a mixture is independent of that exerted by
other gases present.
Gases mix evenly and completely to form a
homogeneous mixture.
Each gas in a mixture behaves as if it were the only gas
present (assuming no chemical reactions).
The pressure of each gas in a mixture is called the
partial pressure.
Dalton’s law of partial pressures:
the total pressure of a gas mixture is the sum
of the partial pressures of each gas.
P1
P2
Ptotal = P1 + P2
PT = PgasA + PgasB + PgasC + etc.
Examples:
1. An organic chemist was considering the pressures
exerted by three gases (M, N, L) in a flask. The total
pressure inside the flask was 456 mmHg. If gas M
contributes 200 mmHg, and gas L contributes 10
mmHg, what is the pressure exerted by gas N.
Examples:
2. An organic chemist was considering the
pressures exerted by three gases (M, N, L) in a
flask. The total pressure inside the flask was
644 mmHg. If gas M contributes to 21% of the
pressure, and gas N contributes 54% what are
the pressures exerted by all three gases in
mmHg.
MOLE FRACTIONS
Mole fraction of gas A =
Moles of gas A_____
Total number of moles of gas
Examples:
1. Four gases are found in an atmospheric sample of
gas. The data below indicates their respective
amount. Determine the mole fraction of each.
GAS
A
B
C
D
AMOUNT IN
MOLES
0.235
1.025
2.35
0.78
GAS
A
B
C
D
AMOUNT IN
MOLES
0.235
1.025
2.35
0.78
What would be the pressure of each gas at standard
pressure in kPa?
HOW DO PARTIAL PRESSURE AND MOLE
FRACTION RELATE?
Pa = Xa PT
Where: Pa = partial pressure of a
Xa = mole fraction of a
PT = total pressure
Examples:
Determine the mole fraction and partial pressure of
oxygen, nitrogen, and argon using the following data.
The total pressure of the system is 760 mmHg.
GAS
O2
AMOUN
T IN
GRAMS
45.6
N2
32.2
Ar
100.76
COLLECTING GASES OVER WATER
•Dalton’s Law can be used to calculate the pressure of gas
collected over water
•Set-up for such a system is shown below

The collection flask initially contains all water
When
a reaction takes place in the reaction
chamber gas travels through tubing and displaces
the water in the collection flask
When
the reaction is complete and no more water
is displaced the flask is stoppered and the gas is
collected WITH WATER VAPOR

To find the pressure of the dry gas you need to
subtract the pressure due to water vapor from the
total pressure. All water vapor pressure values at a
specific temperature are found by using the
reference sheet.
Ptotal = Pgas + PH2O
Examples:
1. A gas is collected over water at 50oC and
barometric pressure of 95 kPa. What is the
pressure exerted by the dry gas?
2. Oxygen gas is collected over water from the
reaction of Na2O2 and water. The oxygen displaces
318 mL of water at 23oC and 1.000atm. What is the
pressure of dry O2.
GAS EQUATIONS
PRESSURE AND VOLUME RELATIONSHIP
As P (h) increases
V decreases
THIS IS CALLED: BOYLE’S LAW
pressure and volume are inversely related
Graphical Relationship:
P1 x V1 = P2 x V2
Constant temperature
Constant amount of gas
A sample of chlorine gas occupies a volume of 946 mL
at a pressure of 726 mmHg. What is the pressure of
the gas (in mmHg) if the volume is reduced at constant
temperature to 154 mL?
P1 = 726 mmHg V1 = 946 mL P2 = ? V2 = 154 mL
P1 x V1 = P2 x V2
P2 =
P1 x V1
V2
726 mmHg x 946 mL
=
= 4460 mmHg
154 mL
TEMPERATURE AND VOLUME RELATIONSHIP
As T increases
V increases
THIS IS CALLED: CHARLES’ LAW
temperature and volume are directly related
Graphical Relationship:
V1 = V2
T1 T2
Temperature must be in Kelvin
Constant pressure
Constant amount of gas
A sample of carbon monoxide gas occupies 3.20 L at
125 0C. At what temperature will the gas occupy a
volume of 1.54 L if the pressure remains constant?
V1 = 3.20 L
T1 = 125oC
398 K
V1 = V2
T1 T2
T2 =
V2 x T1
V1
=
V2 = 1.54 L
T2 = ?
1.54 L x 398 K
3.20 L
= 192 K
THIS IS CALLED: GUY-LUSSAC’S LAW
temperature and pressure are ________related
Graphical Relationship:
Temperature must be in Kelvin
Constant volume
Constant amount of gas
GAY-LUSSAC’S LAW PROBLEM
The gas in a container is at a pressure of 3.00 atm at
25°C. Directions on the container warn the user not to
keep it in a place where the temperature exceeds
52°C. What would the gas pressure in the container
be at 52°C?
Remember: Temperature must be in KELVIN!!!
P1 = 3.00 atm
T1 = 25°C
P2 = ?
T2 = 52°C
P2 = P1T2 = (3.00 atm) (325 K) = 3.27 atm
T1
298 K
OTHER RELATIONSHIPS
What would an equation look like for:
 pressure and amount?
1 2
PT
P2 
T1

volume and amount?
THIS IS CALLED: COMBINED GAS LAW
Boyle’s law and Charles’s law can be combined
into a single equation that can be used for
situations in which temperature, pressure, and
volume, all vary at the same time.
Temperature must be in Kelvin
Constant amount of gas
COMBINED GAS LAW PROBLEM
A helium-filled balloon has a volume of 50.0 L at 25°C
and 1.08 atm. What volume will it have at 0.855 atm
and 10.0°C?
Remember: Temperature must be in KELVIN!!!
MULTI-STEP PROBLEM
Carbon dioxide gas is collected over water at a
temperature of 30.0oC and a pressure of 728 torr. The
volume of gas plus water vapor collected is 27.8mL.
What is the volume of dry carbon dioxide at STP?
(The partial pressure of water vapor at 30oC is 31.8 mmHg)
Remember: Temperature must be in KELVIN!!!
END OF MATERIAL FOR QUIZ #1
AVOGADRO’S LAW
 When amount ______________, volume ____________
 Amount of moles & volume are _____________ related.
Variables: volume , moles
Constants: pressure, temperature
V1 = V2
n1 n2
Because of Avogadro’s law equal volumes of gases at
constant temperature and pressure contain equal
numbers of molecules.
 Avogadro determined one mole of any gas (regardless of
mass differences) will expand to the same volume every
time
standard molar volume of a gas:
22.41410 L (rounded to 22.4 L)
MOLAR VOLUME VIDEO
DERIVING THE IDEAL GAS LAW
Review: Write down the combined gas law; where do you
think “n” fits in?
If both sides must equal each other, we can set one side
equal to a constant. We’ll call this constant “R.”
THE IDEAL GAS LAW EQUATION
PV = nRT
 ideal gas law: relates all variables – pressure,
volume, moles, temperature
DERIVING THE IDEAL GAS LAW CONSTANT

R: ideal gas constant
 Its value depends on the units chosen for
pressure, volume, and temperature in the rest of
the equation.
What are the standard conditions for an ideal gas?
P=
V=
n=
T=
Plug in values into the equation and calculate. What is the constant
that you get?
Usually rounded to 0.0821 (Latm/molK)
NUMERICAL VALUES OF THE GAS CONSTANT “R”
ALWAYS MATCH UP YOUR UNITS!!!!
GAS STOICHIOMETRY
Avogadro’s law can be applied in calculating the
stoichiometry of reactions involving gases.
The coefficients in chemical equations of gas reactions
reflect not only mole ratios, but also volume ratios
(assuming conditions remain the same).
 Discovered by Dalton, while exploring why water was a ratio of
2H to 1O
 example
2H2(g) +
2 molecules
2 mole
2 volumes
O2(g)
→
1 molecule
1 mole
1 volume
2H2O(g)
2 molecules
2 mol
2 volumes
GAS STOICHIOMETRY PROBLEM
Number 1 on Practice Sheet
 What volume of nitrogen at STP would be required
to react with 0.100 mol of hydrogen to produce
ammonia?
N2 + 3 H2  2 NH3
GAS STOICHIOMETRY PROBLEM SOLUTION
0.100 mol H2 x 1 mol N2 x 22.4 L N2
3 mol H2 1 mol N2
= 0.747 L N2
IDEAL GAS LAW SAMPLE PROBLEM

A sample of carbon dioxide with a mass of 0.250 g
was placed in a 350. mL container at 400 K. What
is the pressure exerted by the gas?
P=?
V = 350. mL = 0.350 L
n = 0.250 g = ? mol
T = 400 K
IDEAL GAS LAW PROBLEM SOLUTION
nRT
P
V
P = nRT = .00568 mol (.0821 Latm/molK) 400 K
V
.350 L
= 0.533 atm
GAS STOICH AND IDEAL GAS LAW
Number 2 on Practice Sheet
 What volume of nitrogen at 215OC and 715 mmHg
would be required to react with 0.100 mol of
hydrogen to produce ammonia?
N2 + 3 H2  2 NH3
Note: This system is NOT at STP!!
GAS STOICHIOMETRY PROBLEM SOLUTION
0.100 mol H2 x 1 mol N2 = 0.0333 mol N2
3 mol H2
P = 715 mmHg
V=?
n = 0.0333 mol N2
R = 62.4 LmmHg/molK
T = 25OC + 273 = 488 K
DIFFUSION AND EFFUSION
REMEMBER:
 EFFUSION: process when the molecules of a gas
confined in a container randomly pass through a
tiny opening in the container
 DIFFUSION: the gradual mixing of two or more
gases due to their spontaneous, random motion
GRAHAM’S LAW OF EFFUSION
GRAHAM’S LAW OF EFFUSION
Graham’s law of effusion:
the rates of effusion of gases at the same temperature
and pressure are inversely proportional to the square
roots of
their molar masses.
MB
rate of effusion of A

rate of effusion of B
MA
Sample Problem
 What is the rate of effusion of hydrogen if oxygen has
a velocity of 175 m/s at the same temperature and
pressure.
Graham’s Law of Effusion, continued

Substitute the given values into the equation:
MB
32.00 g/mol
rate of effusion of A
32.00 g/mol



 3.98
rate of effusion of B
2.02 g/mol
MA
2.02 g/mol

Hydrogen rate of effusion is …
GRAHAM’S LAW- VISUAL PROBLEM
Gas Stoichiometry
What is the volume of CO2 produced at 370 C and 1.00
atm when 5.60 g of glucose are used up in the reaction:
C6H12O6 (s) + 6O2 (g)
6CO2 (g) + 6H2O (l)
g C6H12O6
mol C6H12O6
5.60 g C6H12O6 x
6 mol CO2
1 mol C6H12O6
x
= 0.187 mol CO2
180 g C6H12O6
1 mol C6H12O6
V=
nRT
=
P
mol CO2
V CO2
L•atm
x 310.15 K
mol•K
1.00 atm
0.187 mol x 0.0821
= 4.76 L