The Behavior of Gases
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Transcript The Behavior of Gases
The Kinetic Theory
Chapter 13
Today…
Turn in:
Larry the Lawn Chair Guy Reading
Our Plan:
Grab a WS Packet & Calendar
Notes – Kinetic Theory
Worksheet #1
Homework (Write in Planner):
WS #1 – Due next class
Kinetic Theory
The Kinetic Molecular Theory of Matter is a
concept that basically states that atoms and
molecules possess an energy of motion (kinetic
energy) that we perceive as temperature.
In other words, atoms and molecules are
constantly in motion, and we measure the
energy of these movements as the temperature
of that substance.
This means if there is an increase in
temperature, the atoms and molecules will gain
more energy (kinetic energy) and move even
faster.
The Kinetic Theory of Gases
1.
2.
Gases consist of hard, small
spheres
Gas particles have insignificant
volume because they are so
small and so spread out.
Explains…
– measure
of how much the volume of
matter decreases under
pressure
Compressibility
Kinetic Theory
3.
No attractive
or repulsive
forces exist
between
particles
As a result…
Gases
are free to
move in their
containers
Kinetic Theory
4.
Gas particles
move rapidly
in constant
random
motion
Affected by…
Temperature
Volume
and
The effect of volume on
temperature…
Smaller Volume = Faster
Movement of Particles
(more collisions) =
Increase in Temperature
(HOT!)
The effect of volume on
temperature…
Larger Volume = Slower
Movement of Particles
(fewer collisions) =
Decrease in
Temperature (COLD!)
Real Life Example
Smoke
out of a chimney on a
cold winter day hangs in the
air because the gas particles
are moving so slowly (in the
summer smoke travels very
quickly through the air)
Kinetic Theory
5.
All collisions are
perfectly ELASTIC (the
total kinetic energy
remain CONSTANT)
Video Demonstration
http://accad.osu.edu/~midori/GasLaw.html
Quick Check
Summarize the kinetic theory in the space
provided.
Share your responses with a shoulder
partner.
Partner
A shares for 30 seconds and then
Partner B shares for 30 seconds.
Partner A is the student with the most pets.
Gas Pressure
Gas
pressure results from the
collisions of particles with the
walls of a container
If there are no particles, there
cannot be collisions, which means
there would be no pressure. This
explains why there is no pressure
in a vacuum.
Gas Pressure
Air
exerts pressure on Earth because
the gases in our atmosphere push
down (collide with) the Earth’s
surface.
This is called atmospheric pressure.
Atmospheric pressure decreases as
you climb a mountain because there
is less air pressing down on you.
Quick Check
Think
of a pressure in your
life. How does it relate to
pressure as we’ve
discussed here?
Think About it…
What
is the relationship between
kinetic energy and temperature?
Absolute Zero
The temperature of an
object depends on
how fast the particles
in it are moving
Absolute Zero
Absolute Zero (0 K) is
the lowest possible
temperature that can
be reached – it is when
motion of particles
STOPS!
Absolute Zero
Temperature and
Particle Movement
Web Demonstration
Changes of State
Change of State
Boiling
(Vaporization/Evaporation)
Phases
Liquid → Gas
Melting
Solid → Liquid
Condensation
Gas → Liquid
Freezing
Liquid → Solid
Sublimation
Solid → Gas
Deposition
Gas → Solid
Example
Phase Diagram
A
phase diagram tells you the state of
matter at each temperature and
pressure for a substance.
Triple point – when all three states of
matter occur simultaneously in a
container.
Phase Diagram
Phase Diagrams
Two
phases exist on the lines
Water is in a single phase in
each of the colored regions.
At the triple point, water is a
solid, liquid, and a gas at the
same time!
Phase Diagram
Real Life Applications
Cooking
at high altitudes.
Demo – boiling water in a
syringe
Quick Check
Quick Check – Look at the phase diagram for
CO2. Label which state of matter is occurring at
each point.
A
=
B=
C=
Which change of state occurs when you go from point
C to point B?
Which change of state occurs when you go from point
A to point B?
Today…
Turn in:
Finish Lab Test – Weigh & Calculate
Our Plan:
Grab a WS Packet & Calendar
Notes – Kinetic Theory
Worksheet #1
Online Inquiry Lab
Homework (Write in Planner):
WS #1 – Due next class
The Behavior
of Gases
Variables to
describe gases
Variables Used to
Describe Gases
Pressure
Measured
in atm, torr, mm
Hg or Pascals
Barometer
Variables Used to
Describe Gases
Temperature
Measured
in Kelvin,
Fahrenheit, or Celsius
Thermometer
Variables Used to
Describe Gases
Volume
Measured
in
3
Liters or m
Variables Used to
Describe Gases
Amount
of
Gas
Measured
in Moles
STP
Stands
for Standard
Temperature and
Pressure
Standard Conditions of 1
atm pressure and 0
degrees Celsius
Temperature Conversion Factors
K
= C + 273
F = 9/5(C) + 32
C = 5/9 (F – 32)
Other Conversion Factors
Conversion Factors
1 cm3 = 1 mL
1 dm3 = 1 L
1000 Pa = 1 kPa
1000 mL = 1 L
1 atm = 760 mm Hg
1 atm = 101 kPa
1 torr = 1 mm Hg
1000 L = 1 kL
ASSIGNMENT
Complete
Worksheet #1 –
Conversions!
Today…
Turn in:
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Grab your chromebook
Our Plan:
Online Inquiry Labs
Notes
Worksheet #2
Clicker Review - Scenarios
Homework (Write in Planner):
WS #2 – Due next class
Online Inquiry Lab
Go to Mrs. C’s website, Unit 9, Resources
Find 4 “Dates”
Fill
out your date card on p.
8 of your booklet. People at
your table are your family
and we don’t date family!
Gas Laws Challenge!
What
happens to a bag of
potato chips when it is placed
in the freezer?
What happens when it is left in
a hot car?
Gas Laws Challenge!
Aerosol
cans have a warning
on them, indicating not to
incinerate them or to store
them above a certain
temperature. Explain why this
is the case and what will
happen if they are exposed to
extreme temperatures.
Boyle’s Law
Boyle’s Law
Named
after
its founder
Robert Boyle
English
The Original Experiment
Boyle – 1662
Used a manometer – J-shaped
piece of tubing with one end closed
Sealed a certain volume of air in
the closed end of the tube
Varied the pressure (mm Hg) and
watched the change in volume
Robert
The Original Experiment
The Relationship
As
pressure increases,
volume decreases
OR
As pressure decreases,
volume increases
Variables that are Constant
The
amount of gas
(moles)
AND
The temperature of the
gas
The Equation
P1V1 = P2V2
Where
P = Pressure and
V = Volume
Where 1 = Initially (1st) and
2 = Finally (2nd)
The Graph
The Graph
This
is
called an
inverse
relationship
Practice Problem
A
sample of gas has a volume of 12.0
L and a pressure of 1.00 atm. If the
pressure of gas is increased to 2.00
atm, what is the new volume of the
gas?
MATH
ALERT!
Practice Problem
Try it Out!
A
sample of gas has a
pressure of 3.00 atm and a
volume of 4.6 L. If the volume
of gas is decreased to 3.2 L,
what is the new pressure of
the gas? Enter in Clicker!
Quick Check
Come
up with at least 1 reallife application for this gas law
and write it in the appropriate
spot.
Find your 3:00 date and share
your answers.
Real-Life Applications
SYRINGES
To
draw fluids in: the volume is
increased in the syringe, which causes
the pressure inside to be less than that
outside, so the liquid is forced in
To force fluid out: the volume is
decreased, so the pressure inside is
greater than outside, so the fluid is
forced out
Real-life Applications
LUNGS
When
& DIAPHRAGM
we breathe in (inspire), the diaphragm
is lowered and the chest wall is expanded,
increasing the volume for the chest cavity.
Outside air enters the lungs because it is at a
higher pressure than the air in the chest
cavity. When we breathe out (expire), the
diaphragm rises and the chest wall contracts,
decreasing the volume of the chest cavity.
The pressure is increased, and some air is
forced out.
Real-life Applications
Tire
Pump
Air-filled
Automotive
Shock Absorbers
Tire Pressure
Gauge
Real Life Applications
Airplanes
Automobile
Pistons
Meteorology
Straws
Scuba Diving – “The Bends”
Real-Life Applications
Diving
As
– “The Bends”
a diver descends, the water
exerts greater pressure. More gas
pressure is required to keep the
lungs expanded. This increased
gas pressure causes more nitrogen
to dissolve in the divers blood.
Real-Life Applications
Diving
– “The Bends”
Below
a depth of about 30 meters,
dissolved nitrogen interferes with
the transmission of nerve impulses.
The effects are similar to those of
alcohol and include dizziness,
slowed reaction time, and an
inability to think clearly.
Real-Life Applications
Diving
As
– “The Bends”
the diver returns to the surface,
pressure decreases and dissolved
nitrogen is released from the blood.
Bubbles of nitrogen can block small
blood vessels and reduce the supply of
oxygen to cells, causing severe pain in
the joints, dizziness, vomiting, or even
death.
Question
Why are gases
transported under great
pressure?
Charles’ Law
The Inventor
Named after Jacques Charles,
but actually discovered by
Joseph Louis Gay-Lussac
when he was only 23 years
old.
Gay-Lussac named it after
Charles because of his
previous work with gases.
The Inventor
Hot
air balloons were very
popular at the time, so the
two men decided to do
studies on the relationship
between volume and
temperature.
The Original Experiment
Used a manometer – immersed the
J-shaped tube in a water bath. By
adjusting the temperature of the water
they changed the temperature of the
gas in the tube.
Charles and Gay-Lussac watched
what happened to the volume of the
gas when they changed the
temperature
The Relationship
As temperature is increased,
volume increases.
OR
As temperature is decreased,
volume decreases.
Variables that are
constant
Pressure
AND
Amount of gas
(moles)
The Equation
V1 / T1 = V2 / T2
Where
V = volume
and T = Temperature
The Graph
The Graph
This
is
called a
direct
relationship
Practice Problem
The temperature of a 4.00 L sample
of gas is changed from 10.0 degrees
Celsius to 20.0 degrees Celsius.
What will the volume of this gas be at
the new temperature if the pressure is
held constant?
IMPORTANT!
When
solving gas law
problems, all
temperatures must be in
KELVIN!
Practice Problem
Try it Out!
The
○
32 C
volume of a tire at
is 2 L. What is the
temperature if the volume of
the tire is 5.4 L? Enter in
Clicker!
Quick Check
Come
up with at lest 1 real-life
application for this gas law and
write it in the appropriate spot.
Find your 6:00 date and share
your answers.
Real-life Applications
Hot Air Balloons
A propane heater is used to heat
the air in the balloon. As the air is
heated, the gas expands,
becoming less dense. Because
the density of the air inside the
balloon is less than the density
outside the balloon, the balloon is
buoyant.
Real-life Applications
Hot Air Balloons
As the air cools,
it contracts
and becomes more dense
and less buoyant. Thus the
balloonist can control
altitude by heating or
cooling the gas to increase
or decrease buoyancy.
Real-life Applications
Tire
Volume
Bridges
Food in a freezer
Gay-Lussac’s Law
The Experiment
Discovered
by Joseph Louis
Gay-Lussac in 1802
He did experimentation on
hot air balloons
The Relationship
As
the temperature
increases, the pressure
increases
OR
As the temperature
decreases, the pressure
decreases
The Relationship
To
understand the relationship, think
about the kinetic theory – if you
increase the temperature, the
particles move faster and thus hit the
side of the container more often. This
causes the pressure to increase. If
the container is solid, the volume
doesn’t change
Variables that are
constant
Volume
AND
Number of
Moles
The Equation
P1/T1 = P2/T2
Where
P = Pressure
and T = Temperature
The Graph
The Graph
The Graph
This
is a
direct
relationship
Practice Problem
A
gas has a pressure of
0.370 atm at 50 degrees
Celsius. What is the
pressure at standard
temperature?
Practice Problem
Remember to
convert all
temperatures to
Kelvin!
Practice Problem
Try it Out
A gas has a pressure
of 0.891 atm at 120 K.
What is the
temperature at 0.428
atm? Enter in Clicker!
Quick Check
Come
up with at lest 1 real-life
application for this gas law and
write it in the appropriate spot.
Find your 12:00 date and
share your answers.
Real-Life Applications
Aerosol
Cans
Autoclave – machine that
sterilizes medical
equipment
Tire Pressure
Quick Check
Which
gas law describes each
situation on p. 11 of your
notebooklet?
Share your answers with your
9:00 partner.
STOP!
Worksheet
Time!
Complete Worksheet #2
by next class
Wrap Up
Clicker
Review
Today…
Turn in:
Get WS#2 out to check
Our
Plan:
Magic
Squares Review Activity
Notes
WS
#3
Gases Reading
Homework (Write in Planner):
WS #3 & Reading – Due next class
Gas Laws Review
Boyle’s Law
Charles’ Law
Gay-Lussac’s Law
Helpful Reminders!
1.
2.
All Temperatures must be in KELVIN!
Measurements of the same variable must
be in the same units
Can’t have 1 mL and 2 L
Can’t have 123 kPa and 0.9 atm
CONVERT to one or the other
3.
STP (Standard Temperature & Pressure)
Standard Temp = 0 Celsius
Standard Pressure = 1 atm
Review Time
Complete
the Review Worksheet
with a partner. Be sure to each
use 2 different colored writing
utensils and take turns writing!
The Combined Gas Law
Put
all of the Gas Law
Equations together to form
one!
P1V1 = P2V2
T1
T2
Practice Problem
If
a balloon containing 1000L of
gas at 50 degrees Celsius and 101
kPa rises to an altitude where the
pressure is 50.5 kPa and the
temperature is 10 degrees Celsius,
what would the volume of the
balloon be under these new
conditions?
Practice Problem
Practice Problem 2
A
container of krypton
occupies a volume of 15.0 L at
a pressure of 210 kPa and a
temperature of 110 K. Find
the new temperature when the
volume is 25.0 L and the
pressure is 790 kPa.
Practice Problem
Try it Out!
A
○
47 C
sample of gas at
and 1.03 atm occupies a
volume of 2.20 L. What
volume would this gas
○
occupy at 107 C and 0.789
atm? (3.41 L)
Try it Out!
A
gas has a volume of 1.75
L at -23○C and 150 kPa. At
what temperature would the
gas occupy 1.30 L at 210.
kPa? (260 K)
STOP!
Complete
Worksheet #3
by next class.
When you finish choose
a gas reading to
complete by next class.
Today…
Turn in:
Get out WS#3 to check
Turn Reading in to Basket
Our Plan:
Review Problem
Quiz
Lab
Homework
Nothing
(Write in Planner):
Review Problem
If 10.0 liters of oxygen at STP are heated
to 512 °C, what will be the new volume of
gas if the pressure is also increased to
1520.0 mm Hg? 14.4 L
Today…
Turn in:
Nothing – grab goggles and apron and
have pencil for lab (clear off everything
else)
Our Plan:
Penny Mystery Lab
Finish Gas Laws Lab – DUE TODAY
Homework (Write in Planner):
Labs if you don’t finish in class!
Today…
Turn in:
Labs (if you haven’t already)
Our Plan:
Password Vocabulary Review
Notes – Ideal Gas Law
Worksheet #4
Clicker Review
Homework (Write in Planner):
WS #4 – Due next class
The Ideal Gas Law
Ideal Gas Law
Definition
Mathematical
relationship between
pressure, volume,
temperature, and the
number of moles of gas.
The effect of changing moles on
volume
The effect of changing moles on
pressure
The Ideal Gas Law Constant
R
= 0.0821 L x atm
mol x K
The
numbers from the problem must be
in those units to solve!
Volume
in Liters
Pressure in atm
Temperature in Kelvin
The Equation
PV
= nRT
Where
P is pressure, V is
volume, n is the number of
moles, R is the ideal gas
constant, and T is temperature.
Practice Problem
What
is the volume, in
Liters, of 0.250 mole of
o
oxygen gas at 20 C and
0.974 atm of pressure?
Practice Problem
Practice Problem
What
is the pressure, in
atmospheres, of 12
grams of neon gas at
○
32 C that fills a 2L gas
tube?
Practice Problem
STOP!
Begin
#4
working on WS
Today…
Turn in:
Get out WS#4 to Check
Our Plan:
Diffusion Demo
Notes
Worksheet #5 & #6
Test Review
Homework (Write in Planner):
Worksheet #5/#6
Test Review
Test Next Class!
Demo Time…
Ideal Gases vs. Real Gases
An ideal gas is one that follows the gas
laws at all conditions of pressure and
temperature and conforms precisely to the
assumption of the kinetic theory.
Ideal gases do not exist
Real gases:
Do
have volume
There are attractions between particles
Ideal Gas Law & Stoichiometry
Last unit we calculated volumes of gas
produced in chemical reactions using the
molar volume of a gas (22.4 L).
Remember, this only works if the reaction
is carried out at STP (0 degrees C and 1
atm pressure)
Under any other conditions, you must use
stoichiometry in combination with the ideal
gas law.
Example 1
An air sample containing H2S at 0.989 atm
and 29 degrees C is treated with a catalyst to
promote the reaction,
H2S (g) + O2 (g) → H2O (g) + S(s). If 3.2 g of
solid S was collected, calculate the volume
of H2S in the original sample.
Example 2
How much NaN3 is needed to inflate a 50.0
L air bag containing N2 to 1.15 atm at 25.0
ºC given the following chemical reaction?
2 NaN3 (s) → 2 Na (s) + 3 N2 (g)
Try It Out!
In the chemical reaction used in automotive air-bag
safety systems, N2(g) is produced by the decomposition
of sodium azide, NaN3(s), at a somewhat elevated
temperature:
2 NaN3(s) --> 2 Na(l) + 3 N2(g)
What volume of N2(g), measured at 25 °C and 0.980 atm,
is produced by the decomposition of 62.5 g NaN3?
35.9 L
Dalton’s Law of
Partial Pressures
Dalton’s Law of Partial
Pressures
Partial
Pressure: the pressure
of each gas in a mixture
Dalton’s Law: the total
pressure of a mixture of gases
is equal to the sum of the
partial pressures of each
component gas
Dalton’s Equation
PT
= P1 + P2 + P3 + ….
Practice Problem
A
mixture of three gases, A, B,
and C, is at a total pressure of
6.11 atm. The partial pressure
of gas A is 1.68 atm; that of
gas B is 3.89 atm. What is the
partial pressure of gas C?
Practice Problem
6.11 =1.68
Pc
+ 3.89 + Pc
= 0.54 atm
Graham’s Law
Diffusion
Spontaneous
mixing of the
particles of 2 substances caused
by their random motion
Quick Check – Think of examples
Examples:
Smells
Steam/Smoke
Others?
Effusion
Process
by
which gas
particles pass
through a tiny
opening
Video
Graham’s Law of Effusion
The
rate of effusion of a gas
depends on its size.
The more massive a molecule,
the slower it effuses.
Can also be applied to the
diffusion of gases.
Video
Quick Check
Think
of examples of effusion.
STOP!
Complete
WS #5
Begin Test Review
Today…
Turn in:
WS#5
Get Test Review out to Check
Our Plan:
Quiz, Quiz, Trade
Questions on Test Review
Test
Read the Airbag Lab (p. 1 & 2) and answer
questions on p. 3
Homework (Write in Planner):
Enjoy
your Spring Break
Boyle’s Law
P1V1 = P2V2
Charles’ Law
V1/T1 = V2/T2
Gay-Lussac Law
P1/T1 = P2/T2
Combined Gas Law
(P1V1)/T1 = (P2V2)/T2
Ideal Gas Law
PV = nRT
Dalton’s Law
PT = P1 + P2 + P3 +…
Gases Collected Over Patm = Pgas + PH2O
Water
Graham’s Law
rate = √M2/M1
When to Convert…
Kelvin
ALWAYS
PV=nRT
Otherwise, as long as the
variables are in the same unit
you’re fine.
How to do the problems on the
test….
A gas occupies 11.2 L at 0.860 atm. What
is the pressure if the volume becomes
15,000 mL? (0.64 atm)
How to do the problems on the
test….
A sample of hydrogen gas has a volume of
65.0 mL at a pressure of 0.992 atm and a
temperature of 16.0 ○C. What volume will
the hydrogen occupy at 747.84 mm Hg
and 25○C? (67.6 mL)
How to do the problems on the
test….
An engineer pumps 5.00 mol of carbon
monoxide gas into a cylinder that has a
capacity of 20.0 L. What is the pressure in
kPa of CO inside the cylinder at 25.0○C?
(618 kPa)