1. Investigation III: Moving Matter
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

2. Weather Unit – Investigation III
Lesson 1:
Balancing Act

3. ChemCatalyst
Below is a weather map for the United States for September of 2003.
(cont.)
Unit 3 • Investigation III-X

4. What do the large H and L symbols stand for on the map?
(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?
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5. The Big Question What happens when there are changes in air pressure?
Unit 3 • Investigation III-X

6. You will be able to:
Describe what accounts for the pressure on your eardrum when you fly.
Unit 3 • Investigation III-X

7. 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.)
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8. Diagram of what happened
Demo
Observations
Diagram of what happened
Balloon in a bottle
Collapsing can
Submerged cup
Hose with Water
Cup and card
Expanding balloon
Marsh- mallows
Copy this table into your notebook.
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9. 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?
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10. 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 atm.
(cont.)
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11. Notes (cont.)
Air Pressure L H
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12. 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.
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13. 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.
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14. Weather Unit – Investigation III
Lesson 2:
Feeling Under Pressure

15. 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?
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16. Notes
Pressure is force per unit area.
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17. The Big Question
What is the relationship between pressure and volume for gases (if we keep the temperature and amount of gas constant)?
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18. You will be able to:
Explain the change in pressure when there is a change in volume.
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19. Activity
Purpose: This activity allows you to compare the pressure and volume of a sample of air.
(cont.)
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20. Copy this table into your notebook.
(cont.)
Trial
Volume (mL)
Weight (lbs)
Pressure (lbs per in2) 1 2 3 4 5 6
Copy this table into your notebook.
(cont.)
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21. Use a separate piece of graph paper.
(cont.)
Use a separate piece of graph paper.
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22. Making Sense
Why is it so difficult to push the plunger in as the volume gets smaller?
(cont.)
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23. (cont.) (cont.) Trial Volume (mL) Weight (lbs) Pressure (lbs per in2)1
50 mL 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.)
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24. (cont.)
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25. 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.
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26. 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?
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27. Wrap-Up
Pressure and volume have an inverse relationship, that is, when one gets larger, the other gets smaller.
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28. Weather Unit – Investigation III
Lesson 3:
Getting Squeezed

29. 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?
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30. The Big Question
How can the relationship between pressure and volume be expressed as a mathematical equation?
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31. You will be able to:
Understand the relationship between pressure and volume.
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32. 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.)
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33. (cont.)
(cont.)
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34. Copy this table into your notebook. Complete the table:
(cont.)
Copy this table into your notebook. Complete the table:
Trial
Pressure (atm)
Volume (L)
P/V (atm per L)
(PV)L atm 1
1.00
5.00 2
1.25
4.00 3
2.00
2.50 4
3.00
1.67 5 6
6.00
0.83
(cont.)
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35. Use a separate piece of graph paper.
(cont.)
Use a separate piece of graph paper.
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36. 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.)
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37. (cont.) (cont.) Trial Pressure (atm) Volume (L) P/V (atm per L)
(PV)L atm 1
1.00
5.00
0.20 2
1.25
4.00
0.31 3
2.00
2.50
0.80 4
3.00
1.67
1.80 5
3.20 6
6.00
0.83
7.23
(cont.)
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38. (cont.)
(cont.)
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39. (cont.)
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40. 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
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41. 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.)
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42. What is the new pressure? Show your work.
(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.
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43. Wrap-Up
Boyle’s Law can be described by the formula P1V1 = P2V2 provided the temperature and amount of gas are held constant.
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44. Weather Unit – Investigation III
Lesson 4:
Egg in a Bottle

45. 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.)
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46. (cont.)
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47. 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:
Note: The temperature must be in Kelvin (C° + 273).
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48. The Big Question
What causes changes in the pressure of a gas inside a container?
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49. You will be able to: Apply an appropriate gas law to a situation.
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50. 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.)
Unit 3 • Investigation III-X

51. Use a separate piece of graph paper.
(cont.)
Use a separate piece of graph paper.
(cont.)
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52. (cont.) Use a separate piece of graph paper. (cont.)
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53. Copy this table into your notebook.
Volume
Pressure
Temperature
Gas law
V1 = 22.4 L
P1 = 1.0 atm
T1 = 300 K
(initial conditions)
11.2 L
1.0 atm
150 K
Charles’ law
44.8 L
1200 K
2.0 atm
300 K
0.5 atm
89.6 L
22.4 L
600 K
4.0 atm
1,200 K
Copy this table into your notebook.
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54. Making Sense
Describe how the type of container affects how the pressure of the gas inside the container can vary.
(cont.)
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55. Keys to Solving Gas Law Problems:
(cont.)
Keys to Solving Gas Law Problems:
Identify which variable is NOT changing: P, V, or T.
Identify the two variables that ARE changing: P, V, and/or T.
Identify the gas law formula that should be used to solve the problem.
Insert values for P1, V1, T1, P2, V2, or T2 and solve.
(cont.)
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56. Boyle’s Law T and amount of gas are constant
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 gas are constant
Charles’ Law P and amount of gas are constant
Gay-Lussac’s Law V and amount of gas are constant
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57. 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.
Unit 3 • Investigation III-X

58. 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.
Unit 3 • Investigation III-X

59. Weather Unit – Investigation III
Lesson 5:
What Goes Up . . .

60. 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.)
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61. (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.
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62. The Big Question
How does changing both pressure and temperature of a gas affect the volume?
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63. You will be able to:
Use the combined gas law to determine the temperature, pressure, and volume at different points.
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64. 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.
Unit 3 • Investigation III-X

65. 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.)
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66. Copy this table into your notebook.
(cont.)
Altitude
(feet)
Pressure
(atm)
Temperature
(°F and °C)
(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.
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67. Making Sense
Explain why the volume of the balloon continued to increase as it rose.
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68. 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.
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69. 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.
(Amount of gas is constant)
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70. Weather Unit – Investigation III
Lesson 6:
Air On the Move

71. 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?
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72. The Big Question What causes the motion of air in the atmosphere?
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73. You will be able to:
Predict the direction of air movement based on air pressure and temperature.
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74. Activity
Purpose: To integrate ideas about the gas laws and apply them to air movement.
(cont.)
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75. (cont.) (cont.) cool air contracts and descends rising air cools
warm land
cool ocean
low pressure air
warm air expands and rises
cool air contracts and descends
rising air cools
descending air warms
high pressure air
(cont.)
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76. (cont.)
(cont.)
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77. (cont.)
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78. Making Sense
How do temperature and pressure affect air movement on the planet?
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79. 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.)
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80. Notes (cont.)
(cont.)
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81. Notes (cont.)
(cont.)
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82. Notes (cont.)
(cont.)
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83. 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.)
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84. Notes (cont.)
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85. Check-In
Winds tend to blow down the eastern sides of mountains. What type of weather do you expect on the eastern side?
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86. 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.
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