Gases Book

Gas Experiments

Index Air Can Be Stretched

3

Air Has Mass

4

Air Pressure - Index Card

5

Air Pressure - Newspaper

6

Balloon in a Bottle

7

Crush the Can

8

Tissue in a Cup

9

Supply List

10

References

11

Children’s Literature

12

Notes

13

Air Can Be Stretched

Index

The purpose of this experiment is to show that the volume of air in a closed system (a system where variables are constant until changed) varies with the temperature.

Materials

Ballons String Hot plate Small cooler Dry ice or liquid nitrogen Large coffee can Water

What To Do

Start with two inflated balloons, approximately the same size in circumference. Measure the circumference of each balloon at room temperature by wrapping the string around the balloon. If you are in a classroom with a blackboard, you may also wish to trace each balloon on the board.

Boil water in the coffee can on the hot plate. Put one balloon in the coffee can and let it sit and start to get bigger. Leave it in the can as you do the next part of the experiment. Put the other balloon in the cooler. If using dry ice, leave it set for at least 5 minutes before measuring. If using liquid nitrogen, measure the circumference immediately following the pouring of liquid nitrogen over the balloon. Either way, measure the balloon again using the same string. Now return to the balloon that is warming up. It should appear as if the balloon is climbing out of the can because it has gotten larger. Remove the balloon from the can and immediately measure it with the same string you used before.

Questions

1. How did the circumference of the balloon placed in the boiling water change? What about the balloon in the dry ice?

2. Predict what would happen if the balloon were exposed to even colder temperatures. What about even warmer temperatures?

Summary

As the temperature increases, the volume of the air in the balloon increases. As the temperature decreases, the volume of the air in the balloon decreases. By changing temperature, the space occupied by the air (the volume of the air) changes.

Source

“Science is Fun” in “Fundamentals of Physical Sciences.” Janet Z. Tarino, The Ohio State University, 1990. © S. Olesik, WOW Project, Ohio State University, 1999.

Air Has Mass

Index

The purpose of this experiment is to illustrate that air does indeed have mass.

Materials Yardstick Balloons String

What To Do

Suspend the yardstick from the ceiling or some other object that allows it to be freely suspended.

Make sure that the string is at the exact center (on a yardstick this is at 18 inches). Adjust the string so the yardstick is evenly balanced and hangs horizontally. Tape a balloon to either end (the balloons should not be blown up). Make sure the yardstick is still balanced horizontally.

Remove one balloon, blow it up, and replace it.

Questions

1. What happens to the yardstick when the blown-up balloon is placed on one end that is different from when the neither of the balloons was blown up?

2. What caused this change?

Summary

The mass of the air in the balloon causes the yardstick to tip. The reason students do not feel the weight of the air on them is that they have never been without it!

Extension

The density of air is 1.225 kg/m3 at 15º C and sea level. Calculate the approximate volume of air in the classroom in cubic meters. Using the density of air, what is the mass of the air in the classroom?

Source

“Science Is.” Susan V. Bosak. Scholastic Press, 1991. ISBN 0-5907-4070-9 © S. Olesik, WOW Project, Ohio State University, 1999.

Air Pressure - Index Card

Index

Air is all around us and it exerts pressure in all directions. This experiment will show the exertion of air pressure on the index card.

Materials

Small, transparent plastic cup 4” x 6” index card Water

What To Do

Fill a cup 1/2 - 3/4 full with water. Wet the lip of the glass with water and place the index card on top of the cup. While holding the index card in place with one hand, use the other hand to flip the cup upside down. Continue to hold the cup upside down and remove your hand from the index card. What happens? To flip the cup right side up, hold the index card to the cup and quickly flip the cup.

Questions

1. When the cup is upside down what is pushing on the card? What is pushing on the card from above? From below?

2. Explain why the index card does not fall off.

Summary

The pressure applied to the index card by the water is less than the pressure applied by the air.

In other words, the air is pushing up on the card more than the water is pushing down on it.

Therefore, the air pressure is holding the paper snug against the cup.

Source

“Science Is.” Susan V. Bosak, Scholastic Press, 1991. ISBN 0-590-74070-9 © S. Olesik, WOW Project, Ohio State University, 1999.

Air Pressure - Newspaper

Index

Air is all around us and it exerts pressure in all directions. This experiment will show the exertion of air pressure on the newspaper.

Materials

Sheet of newspaper Ruler

What To Do

Spread the newspaper smoothly across a table. If the newspaper was folded, make sure the inside of the paper is facing up and the outside is facing the table (otherwise air gets underneath and the results are not what they need to be). Place the ruler partway underneath the paper, with one end of the ruler extending beyond the edge of the table a few inches. Bring your hand down on the end of the ruler extended beyond the table edge (you can push as hard as you like!)

Question

1. Why doesn’t the paper go flying into the air?

Summary

The pressure applied to the newspaper by the ruler by the experimenter’s hand is less than the pressure applied by the air. In other words, the air is pushing down on the newspaper more than the ruler is pushing up on it. Therefore, the air pressure is holding the newspaper to the table. The force needed to lift the newspaper into the air is too large to produce with the ruler.

Source

NASA Website: http://ldaps.ivv.nasa.gov/curriculum/curriculum/airpressure2.html © S. Olesik, WOW Project, Ohio State University, 1999.

Balloon in a Bottle

Index

The goal of this experiment is to show that an “empty” pop bottle is not really empty. It contains air and air takes up space.

Materials

2 Liter plastic pop bottle 2 Liter plastic pop bottle with hole in side Balloon

What To Do

Ask students what happens when air is blown into a balloon. Ask them to predict what will happen when air is blown into a balloon in a bottle.

Push the balloon into the bottle without a hole and spread the small open section of the balloon over the mouth of the bottle.

Try blowing up the balloon. Ask students to explain what they observed.

Now use the bottle with the hole in the side. Ask students to predict what will happen when air is blown into the balloon this time. Try blowing up the balloon again.

Questions

1. Have a student put his/her hand near the exit hole of the bottle when another student is filling a fresh, clean balloon with air. What is escaping the bottle?

2. What does this experiment teach us about air?

Summary

It is difficult to blow up the balloon initially because the air trapped inside of the bottle is taking up space inside the bottle. For the balloon to expand into the bottle the air in the bottle must be compressed to allow space for the balloon or the air must be able to somehow exit the bottle.

By using a bottle with a hole in the side, air is allowed to escape from the bottle as the balloon is blown up.

Source

“Teaching Chemistry with Toys: Activities for Grades K-9.” McGraw-Hill, Terrific Science Press, 1995. ISBN: 0-07-064722-4 © S. Olesik, WOW Project, Ohio State University, 1999.

Crush the Can

Index

The goal of this experiment is to show that air exerts pressure on the soda can.

Materials

12 oz. aluminum soda can Hot plate Tongs Large pail of water

What To Do

Add water to the soda can so that the bottom of the can is just covered. Place the can on the hot plate and allow the water to boil. When steam can be seen coming out of the can use the tongs to pick up it up. Quickly turn the can upside down and dip it into the pail of water so that most of the can remains above water but the opening on the can is completely submerged.

Questions

1. What happens to the can?

2. What caused that to happen to the can?

Summary

Before the addition of the water to the soda can, the can is filled with air. When water is added some of the air is displaced. Heating the water causes it to boil and the resulting steam expands inside the can, pushing most of the remaining air out of the can. When the can is cooled in the room temperature water, the steam changes to liquid water, which takes up much less space than steam. This change takes place while the opening of the can is under water, so no air is able to rush into the can to take up the extra space. The pressure inside the can is therefore much less than the pressure on the outside of the can, and so the can implodes.

Source

“Science is Fun: Fundamentals of Physical Sciences.” Janet Z. Tarino, OSU, 1990. © S. Olesik, WOW Project, Ohio State University, 1999.

Tissue in a Cup

Index

Air is matter and therefore it must take up space. This experiment dramatically illustrates the fact that an empty cup is truly not empty. It is filled with air.

Materials

2 plastic cups, 1 with a hole in the bottom 2 paper towels or tissues Double-sided tape Large beaker (1000 mL) or large pail

What To Do

Ball up a small piece of paper towel or tissue. Using double sided tape attach the towel or tissue to the inside bottom of the plastic cup without a hole. Fill the pail of water or beaker approximately half full. Ask students to predict what will happen to the paper towel when the cup is dunked upside-down in the water. Hold the bottom of the plastic cup. Push the plastic cup into the water with the open end of the cup pointing down into the water. Pull the cup out of the water.

Have the students inspect the tissue or paper towel. Now do the same experiment, except with the cup that has the hole in the bottom. Ask students how this will change what happens to the paper towel when the cup is placed in the water. Try the experiment again.

Questions

1. Ask the students to tell you what happened to the tissue.

2. Let the students tell you their ideas on why there was a difference between the condition of paper towel with and without the hole in the bottle of the cup.

Summary

When the tissue is added to the cup the remainder of the cup continues to be filled with air. When the cup is submerged, because air is compressible some water will enter the cup. But, because two types of matter cannot occupy the same space simultaneously, the compressed air serves as a barrier between the tissue and the water and the paper remains dry.

Extension

Ask the students to add more and more paper to the bottom of the cup until it becomes wet when submerged.

Source

“Teaching Chemistry with Toys: Activities for Grades K-9.” McGraw-Hill, Terrific Science Press, 1995. ISBN: 0-07-064722-4 © S. Olesik, WOW Project, Ohio State University, 1999.

Supply List Air Can Be Streched

Balloons String Hot plate Small cooler Dry ice or liquid nitrogen Large coffee can Water

Air Has Mass Yardstick Balloons String

Air Pressure - Index Card Small, transparent plastic cup 4� x 6� index card Water

Air Pressure - Newspaper Sheet of newspaper Ruler

Air Takes Up Space - Balloon in a Bottle

2 Liter plastic pop bottle 2 Liter plastic pop bottle with hole in side Balloon

Air Takes Up Space - Tissue in a Cup 2 plastic cups, 1 with a hole in the bottom 2 paper towels or tissues Double-sided tape Large beaker (1000 mL) or large pail

Crush the Can

12 oz. aluminum soda can Hot plate Tongs Large pail of water

Index

References

Index

“Science is Fun” in “Fundamentals of Physical Sciences.” Janet Z. Tarino, The Ohio

State University, 1990.

“Science Is.” Susan V. Bosak. Scholastic Press, 1991. ISBN 0-5907-4070-9 “Teaching Chemistry with Toys: Activities for Grades K-9.” McGraw-Hill, Terrific

Science Press, 1995. ISBN: 0-07-064722-4 NASA Website: http://ldaps.ivv.nasa.gov/curriculum/curriculum/airpressure2.html

Children’s Literature

Index

“Science Magic With Air.” By Chris Oxlade. Aladdin Books Ltd.: London, 1993.

ISBN 0-8120-1983-0.

“What is the World Made of? All About Solids, Liquids, and Gases.” By Kathleen

Weidner Zoehfeld, illustrated by Paul Meisel. HarperCollins Publishers: New

York, 1998. ISBN 0-06-445163-1.

Notes

Index

There are currently no notes on this unit. If you have suggestions or changes to make on the experiments or units, please email us! Our address is wow@ chemistry.ohio-state.edu. Š S. Olesik, WOW Project, Ohio State University, 2002.

Copyright Š 2002-2010 by S.Olesik, Wonders of Our World Project (WOW), the Ohio State University. Permission to make digital or hard copies of portions of this work for personal or classroom use is granted without fee provided that the copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page in print or the first screen in digital media. Abstracting with credit is permitted.