Where’s the Air?Where’s the Air?

Investigation 2- Where’s the Air?

• Investigation 2- Where’s the Air?• Enduring Understanding: • Weather occurs in the atmosphere and the atmosphere is

composed of air, which has mass and can be compressed.• Learning Goals: • I will conduct experiments to determine that air has mass. • I will use a molecular model to compare gas at standard

pressure and a gas under increased pressure. • I will explain how explain how experimental results provide

evidence that air has mass.

Quick WriteQuick Write

•Where does weather happen?

–ATMOSPHERE

AIRAIR• In our first investigation we

used a variety of weather tools to measure weather conditions. Air plays a very important role in the weather. In the next few days we are going to look more closely at air to learn some of its properties.

SYRINGESYRINGE• This is a syringe. You can

use it to investigate air. You can work with your syringe alone or with other students, but you should not use the syringe to annoy another student!

SYRINGESYRINGE• Things that annoy other

students:–Blowing the syringe in their face

–Taking someone elses syringe without asking

MATERIALSMATERIALS• You have the following materials–Syringe–Tubing–Binder clip

SYRINGESYRINGE• See if you can answer these questions:–What happens to the air in the syringe when you push and pull on the plunger?

–What can air do?

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Example: When you push the plunger down, the air in the syringe is pushed out the tube.

Example: Does air have weight?

Air ObservationsAir Observations• When you clamp the tube closed

and push the plunger down, what happens to the air?–The air is pushed into a smaller

space.• Is there more air, less air, or the

same amount of air in the syringe when the air is pushed into a smaller space?–Same amount

Air ObservationsAir Observations• What happens when you let go of

the plunger after pushing down?–The air pushes the plunger back

up.• What do you think happens to the

air when it is pushed into a smaller space?

• What happens to push the plunger back out when you release the pressure on the plunger?

COMPRESSIONCOMPRESSION• When you push on the

plunger, the air is forced into a smaller space. We say the air is compressed. The same amount of air is still in the syringe when it is compressed.

PRESSUREPRESSURE• Compressed air pushes back

with a force equal to the force compressing it. If the force on the plunger is released, the pressure in the compressed air will push the plunger out. The compressed air pushes back, and the push is called pressure!

GAS IN A SYRINGE

AIRAIR• Everything is made out of atoms and molecules, including air. The molecules in gases are free to move around throughout the volume of gas. There is a lot of space between the molecules in gases.

AIRAIR• When a volume of gas is compressed into a smaller space, the molecules are pushed closer together. The number of molecules is the same; they are just closer together.

AIRAIR• Molecules compressed into a

smaller space bump into one another more often, and this creates pressure. Pressure pushes in all directions, and if the force keeping the gas compressed is reduced, the gas will expand into a larger space and the molecules will get farther apart.

WORD BANK• Compression- When air is forced into

a smaller space.• Pressure- compressed molecules

pushing back with a force equal to the force that compressed it.

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Let’s review our questionsLet’s review our questions

Example: Does air have weight?

From YesterdayFrom Yesterday

• True or False: The syringe on the left has more air than the syringe on the right. Explain.

Where’s the Air?Where’s the Air?

QuestionsQuestions• Does air have weight (mass)?• Where does air pressure come

from?• How does air push the syringe

plunger out?• Why is air pressure so strong?

QuestionsQuestions• Does air have weight (mass)?

– Balloon Clip

Does air have mass?Does air have mass?• Every object and substance in

the world is made of matter. Matter is the stuff that everything is made of. The amount of matter in an object is its mass. Mass is the measurement of the amount of matter in an object or a substance such as air. Mass is measured in grams.

Does air have mass?Does air have mass?• One way to confirm that

something has mass is to weigh it. Weight is pull or force between Earth and the matter in an object or substance. Weight can vary slightly at different places on Earth and can vary greatly on different planets.

Does air have mass?Does air have mass?• In outer space, away from

planets, objects become weightless, but their mass does not change.

• So let’s restate our question: –Does air have mass?–Is there any matter in a volume of air?

EXPERIMENTEXPERIMENT• What experiment can we conduct

to find out if air has mass?Mass Video:

Mass vs. Weight

• http://www.youtube.com/watch?v=1whMAIGNq7E&lr=1

READING:READING:“What’s in the Air”“What’s in the Air”

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What’s in the Air ****ANSWER ALL QUESTIONS IN COMPLETE SENTENCES. USE THE QUESTI ON TO ANSWER THE QUESTI ON. 1. What is the diff erence between permanent gases and variable gases in the atmosphere? __________________________________ __________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ ________________________________________________________________________________________________________________ 2. During the daylight hours, plants and algae take in carbon dioxide and release oxygen. I f humans continue to destroy rain f orests, what might happen to the balance between these gases? _________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________________________________________________________________________________________________________ 3. What was the most interesting thing you learned f rom this reading? ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 4. What was the author’s purpose in this selection? A) to entertain B) to persuade C) to inf orm

WORD BANK

• Matter- the stuff everything is made of.

• Mass- the amount of matter in an object measured in grams.