Transcript Weather Unit

Weather Unit
Investigation III:
Moving Matter
Lesson 1: Balancing Act
Lesson 2: Feeling Under Pressure
Lesson 3: Getting Squeezed
Lesson 4: Egg in a Bottle
Lesson 5: What Goes Up . . .
Lesson 6: Air On the Move
Weather Unit – Investigation III
Lesson 1:
Balancing Act
ChemCatalyst
Below is a weather map for the United
States for September of 2003.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
• What do the large H and L symbols
stand for on the map?
• What do you think these areas have to
do with weather?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
The Big Question
• What happens when there are
changes in air pressure?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
You will be able to:
• Describe what accounts for the
pressure on your eardrum when
you fly.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Activity
Procedure:
For each demonstration, describe what
happened. Make a diagram with arrows
to show what is happening with the air in
each experiment. Be sure to include
what happens to the air in the
atmosphere in addition to the air
contained inside the balloon, can, cup,
hose, and marshmallows.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Demo
Observations
Diagram of what happened
Balloon in
a bottle
Collapsing
can
Submerged
cup
Hose with
Water
Cup and
card
Expanding
balloon
Marshmallows
Copy this table into your notebook.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Making Sense
• What evidence do you have that air
pressure changes?
• How are air pressures equalized in
each demonstration?
• What can cause changes in air
pressure?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes
• Air pressure can be defined as the
force caused by the molecules of the
gases striking the walls of the container
they are in.
• The air pressure all around us, all the
time, is called atmospheric pressure.
• If you are standing at sea level and it is
about 25˚C out, you are experiencing
one atmosphere of pressure—called 1
(cont.)
atm.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes (cont.)
Air Pressure
L
H
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Check-In
When we fly in a commercial airplane we
often feel the change in air pressure in
our ear canals. It feels painful.
• Using what you learned today, explain
what you think is going on.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Wrap-Up
• Gas pressure is defined as the force
per area caused by the molecules of a
gas colliding with and pushing on the
walls of its container.
• When pressure due to gases in a
container balance pressure due to air
on the outside, the container stops
expanding or contracting.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Weather Unit – Investigation III
Lesson 2:
Feeling Under Pressure
ChemCatalyst
• Which balloon contains the greatest
volume of material? Explain why you
think so.
• Which balloon weighs more?
• Which material is exerting more
pressure on the walls of the balloon?
How can you tell?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes
• Pressure is force per unit area.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
The Big Question
• What is the relationship between
pressure and volume for gases (if we
keep the temperature and amount of
gas constant)?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
You will be able to:
• Explain the change in pressure when
there is a change in volume.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Activity
Purpose: This activity allows you to
compare the pressure and volume of a
sample of air.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Trial
1
2
3
Volume (mL) Weight (lbs) Pressure (lbs per in2)
4
5
6
Copy this table into your notebook.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Pressure vs. Volume of Air in Syringe
20
Pressure (lbs/in2)
15
10
5
0
0
10
20
30
40
50
Volume (mL)
Use a separate piece of graph paper.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Making Sense
• Why is it so difficult to push the plunger
in as the volume gets smaller?
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Trial
Volume (mL)
Weight (lbs)
Pressure (lbs per in2)
1
50 mL
0
0
2
40 mL
10
3.2
3
30 mL
15
4.8
4
20 mL
25
8.0
5
15 mL
35
11.1
6
10 mL
55
17.5
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Pressure vs. Volume of Air in Syringe
20
Pressure (lbs/in2)
15
10
5
0
0
10
20
30
40
50
Volume (mL)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes
• Gas pressure and volume have an
inverse relationship.
• When the volume of a given amount of
gas is decreased, its pressure
increases. When the volume of a given
amount of gas is increased, its
pressure decreases.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Check-In
Imagine you have a plastic bottle that is
capped. It contains nothing but air.
• What happens to the volume the bottle
if you squeeze the bottle tightly?
• What happens to the pressure inside
the bottle when it is squeezed?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Wrap-Up
• Pressure and volume have an inverse
relationship, that is, when one gets
larger, the other gets smaller.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Weather Unit – Investigation III
Lesson 3:
Getting Squeezed
ChemCatalyst
Imagine you have a 5.0 L tank full of
helium at a pressure of 50 atm, and a
large weather balloon to fill up.
• How does the volume of the helium
gas change as it fills up the balloon?
• How does the pressure of the gas
change now that it is in the balloon?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
The Big Question
• How can the relationship between
pressure and volume be expressed as
a mathematical equation?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
You will be able to:
• Understand the relationship between
pressure and volume.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Activity
Purpose: This activity allows you to gain
practice with calculations of gas pressure
and volume.
A gas sample occupying a volume of 5.00
liters and at a pressure of 1 atm is
contained in a cylinder with a movable
piston. As the volume inside the piston is
decreased, the pressure is measured. The
pressures for several volumes of gas are
given in the table below.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Copy this table into your notebook.
Complete the table:
Trial
1
2
3
4
5
6
Pressure
(atm)
1.00
Volume
(L)
5.00
1.25
2.00
3.00
4.00
2.50
1.67
4.00
6.00
1.25
0.83
P/V
(atm per L)
(PV)L
atm
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Pressure vs. Volume of Air in Piston
8
7
Pressure (atm)
6
5
4
3
2
1
0
0
1
2
3
4
5
6
Volume (L)
Use a separate piece of graph paper.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Making Sense
Explain the best way to figure out the
new volume of a gas if you know the
following:
• P1 - beginning pressure
• V1 - beginning volume
• P2 - new pressure
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Trial
Volume (L)
1
Pressure
(atm)
1.00
(PV)L atm
5.00
P/V
(atm per L)
0.20
2
1.25
4.00
0.31
5.00
3
2.00
2.50
0.80
5.00
4
3.00
1.67
1.80
5.00
5
4.00
1.25
3.20
5.00
6
6.00
0.83
7.23
5.00
5.00
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Pressure vs. Volume of Air in Piston
8
7
Pressure (atm)
6
5
4
3
2
1
0
0
1
2
3
4
5
6
Volume (L)
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Pressure vs. Inverse Volume
8
Pressure (atm)
6
4
2
0
0
0.5
1
1/Volume (L)
1.5
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes
Boyle’s Law
The pressure of a given amount of gas is
indirectly proportional to volume, if the
temperature is kept constant.
P1V1 = P2V2
where the temperature
and amount of gas
are constant
This can also be written: P1/P2 = V1/V2
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Check-In
A balloon full of gas occupies 7.5 L and
is at a pressure of 1.0 atm. Calculate the
new pressure of the gas if the balloon is
taken underwater to a depth where its
new volume is 2.5 L.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
• Did the volume of the balloon decrease
or increase when it was taken
underwater?
• What do you predict will happen to the
pressure, will it increase or decrease?
Explain your thinking.
• What is the new pressure? Show your
work.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Wrap-Up
• Boyle’s Law can be described by the
formula P1V1 = P2V2 provided the
temperature and amount of gas are
held constant.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Weather Unit – Investigation III
Lesson 4:
Egg in a Bottle
ChemCatalyst
You start at sea level where the pressure is
1.0 atm. Suppose you climb high up a
mountain where the pressure is 0.75 atm.
Assume the temperature does not change.
• Does the pressure inside your unopened
bag of potato chips change? Explain.
• Does the pressure inside your unopened
glass bottle of soda change? Explain.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes
Boyle’s Law
The pressure of a given amount of gas is
directly proportional to temperature, if
the volume is kept constant.
This relationship is expressed as:
P1 P2

T1 T2
Note: The temperature must be in Kelvin
(C° + 273).
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
The Big Question
• What causes changes in the pressure
of a gas inside a container?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
You will be able to:
• Apply an appropriate gas law to a
situation.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Activity
Purpose: This activity provides practice
with the gas laws. You will explore what
happens to the volume, temperature,
and pressure of a quantity of air in a
container with variable volume and in
one with fixed volume.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Pressure vs. 1/Volume of the Balloon
(cont.)
1.25
Pressure (atm)
1
0.75
0.5
0.25
0
0
0.001
0.002 0.003
0.004 0.005
1 / Volume (mL)
Use a separate piece of graph paper.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Pressure vs. Temperature of the Balloon
1.25
Pressure (atm)
1
0.75
0.5
0.25
0
0
50
100
150
200
250
300
Temperature (K)
(cont.)
Use a separate piece of graph paper.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Volume
V1 = 22.4 L
Pressure
Temperature
P1 = 1.0 atm T1 = 300 K
11.2 L
1.0 atm
44.8 L
1.0 atm
150 K
Charles’ law
Charles’ law
1.0 atm
1200 K
2.0 atm
300 K
0.5 atm
300 K
89.6 L
300 K
22.4 L
150 K
22.4 L
600 K
4.0 atm
Gas law
(initial conditions)
1,200 K
Copy this table into your notebook.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Making Sense
• Describe how the type of container
affects how the pressure of the gas
inside the container can vary.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Keys to Solving Gas Law Problems:
1. Identify which variable is NOT
changing: P, V, or T.
2. Identify the two variables that ARE
changing: P, V, and/or T.
3. Identify the gas law formula that
should be used to solve the problem.
4. Insert values for P1, V1, T1, P2, V2, or
T2 and solve.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
For a given amount of gas, the volume V,
the temperature T in Kelvin, and the
pressure P are related.
• Boyle’s Law
T and amount of
P1V1  P2 V2
gas are constant
• Charles’ Law
V1 V2
P and amount of

gas are constant
T1 T2
• Gay-Lussac’s Law
P1 P2
V and amount of

gas are constant
T1 T2
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Check-In
• The Gladstone family went for a drive
in the desert. In the morning, the air
pressure in the tires was around 28
pounds per square inch (psi). Around 3
PM in the afternoon, the tire pressures
were around 32 psi. Explain what
might be going on.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Wrap-Up
• Pressure and temperature of a gas are
proportional if the volume is fixed. That
is, when one gets larger, the other gets
larger.
• When applying the gas law equations,
it is important to understand which
variable is held fixed.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Weather Unit – Investigation III
Lesson 5:
What Goes Up . . .
ChemCatalyst
A weather balloon is inflated
to a volume of 12,500 L with
helium. When it is released
from the ground the air
pressure is 1 atmosphere and
the air temperature
is 17°C.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
• At a specific altitude the weather
balloon pops and returns to the
ground. Use your understanding of the
gas laws to explain why this happens.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
The Big Question
• How does changing both pressure and
temperature of a gas affect the
volume?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
You will be able to:
Use the combined gas law to determine
the temperature, pressure, and volume
at different points.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes
The Combined Gas Law is simply a
mathematical compilation of Charles’s Law,
Boyle’s Law, and Gay-Lussac’s Law.
• It allows us to calculate volume,
temperature, or pressure when all three
variables change.
• In the combined gas law, the amount of gas
is constant.
P1V1 P2V2

T1
T2
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Activity
Purpose: This activity will allow you to
track how volume, pressure, and
temperature of a gas are interrelated.
You will be using the combined gas law
to calculate the changes in a weather
balloon.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
Altitude
(feet)
Pressure
(atm)
Temperature
(°F and °C)
Temperature
(K)
Volume
(L)
0 (sea level)
1.0 atm
63°F
17°C
290 K
12,500 L
5,000 ft
0.8 atm
41°F
5°C
278 K
10,000 ft
23°F
–5°C
25,000 ft
–30°F
–35°C
40,000 ft
–70°F
–57°C
Copy this table into your notebook.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Making Sense
• Explain why the volume of the balloon
continued to increase as it rose.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Check-In
A sample of neon gas occupies a volume
of 1.0 L at 300 K at 1.0 atm. Suppose
you increase the temperature to 600 K
and the pressure increases to 4.0 atm.
• Does the volume of the gas increase
or decrease? Explain your answer.
• Calculate the volume of the gas at
50°C and 4.0 atm.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Wrap-Up
• If volume, temperature, and pressure
are all varying, then you can use the
combined gas law to determine the
effects of changing two variables on
the third.
P1V1 P2V2

T1
T2
(Amount of gas is constant)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Weather Unit – Investigation III
Lesson 6:
Air On the Move
ChemCatalyst
The morning wind is still. The sun is
shining. By afternoon, breezes blow off
the ocean onto the land.
• If the winds blow from the ocean to the
land, where is the pressure higher?
Explain your thinking.
• How does the air pressure change
when air over the land warms and
expands?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
The Big Question
• What causes the motion of air in the
atmosphere?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
You will be able to:
Predict the direction of air movement
based on air pressure and temperature.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Activity
Purpose: To integrate ideas about the
gas laws and apply them to air
movement.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
cool air contracts and
descends
rising air cools
warm air expands and
rises
descending air
warms
high pressure air
cool ocean
low pressure air
warm
land
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Making Sense
• How do temperature and pressure
affect air movement on the planet?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes
• Areas of high and low pressure on the
planet are the major cause of what we
call winds.
• Air pressure differences start the wind
blowing.
• The greater the difference in
pressures, the stronger the force of the
wind.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes (cont.)
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes (cont.)
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes (cont.)
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes (cont.)
• When meteorologists talk about the jet
stream they are referring to winds that
are in the upper atmosphere, above
20,000 feet.
• These winds travel at least 57 mph
and are largely responsible for pushing
storms around on the planet.
(cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Notes (cont.)
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Check-In
• Winds tend to blow down the eastern
sides of mountains. What type of
weather do you expect on the eastern
side?
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X
Wrap-Up
• Winds are caused by air moving from
regions of high pressure to regions of low
pressure.
• Air warmed at the earth’s surface,
expands, rises, and subsequently cools.
This creates a low pressure system.
• Cool air descending from high altitudes,
contracts, descends, and subsequently
warms. This creates a high pressure
system.
© 2004 Key Curriculum Press.
Unit 3 • Investigation III-X