Key Concepts

In a gas, the molecule have really weak attractions because that one another. Molecules are able come move openly past each various other with small interaction between them. The molecule of a gas are much much more spread out and move independently compared to the molecule of liquids and solids. Whether a substance is a solid, liquid, or gas in ~ a particular temperature relies on the balance between the movement of the atom or molecule at the temperature and how solid their attractions space for one another.Heating a gas rises the speed of the molecules. Cooling a gas reduce the speed of that molecules.


This lesson concentrates on molecular movement in gases. Students compare the massive of a basketball when it is deflated and after it has been inflated. The inflated ball has actually the greater mass for this reason students deserve to conclude the gas is matter since it has actually mass and takes up space. Then students take into consideration how heating and also cooling affect molecular motion in gases. Lock dip the mouth that a party in detergent solution and also observe a balloon growing and also shrinking once the bottle is warmed and also cooled. College student will learn that the attractions between gas molecules are so minimal that attractions can’t be offered to explain the behavior of gases prefer it can for liquids and solids.


Based on observations of demonstrations and also their own experimentation, college student will be able to describe gas as matter. College student will also be able come describe, top top the molecule level, the result of heating and also cooling on the movement of molecule of a gas.


Download the student activity sheet, and also distribute one per student once specified in the activity. The activity sheet will serve as the “Evaluate” ingredient of every 5-E great plan.

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Be sure you and also the student wear properly fitting goggles.Students must use care when taking care of hot madness water.

Materials because that Each Group

2 clear plastic cups8-oz plastic bottleDetergent equipment in a cupHot water (about 50 °C)Cold water

Materials because that the Demonstration

Basketball, an extremely deflatedBalance that actions in gramsPumpCan the compressed gas (available at any kind of office supply store)

Do a demonstration to present that gas has actually mass.

You will require a balance that actions in grams because that either demonstration. If friend don’t have actually this kind of balance, friend can show videos of every demonstration: Air has actually Mass, Basketball and Air has Mass, Can.

Materials because that the demonstration

Basketball, very deflatedBalance that procedures in gramsPumpCan the compressed gas (available at any office it is provided store



Place the deflated sphere on the balance to gain the early stage mass.


Ask students if they think the sphere will weigh an ext or less after girlfriend pump air into it.

Pump as much air right into the basketball together you can and then put it back on the balance.

Can of compressed gas

Place a deserve to of compressed gas ~ above a scale and check the mass.


Ask students even if it is it will weigh more, less, or the very same if friend squeeze the trigger and also let part gas out.

Shoot gas out of the can for a couple of seconds and then location the can ago on the scale.


Expected results

The basketball have to weigh 2–4 grams more than once it to be deflated. The can will weigh a few grams much less than that did initially.


Have students perform an activity to uncover out just how heating and also cooling influence gases.

Question to investigate

How does heating and also cooling impact a gas?

Materials because that each group

2 clean plastic cups8-oz plastic bottleDetergent equipment in a cupHot water (about 50 °C)Cold water

Teacher Preparation

Make the detergent equipment for the entire class by adding 4 teaspoons that dishwashing liquid and 4 teaspoons of sugar to ½ cup that water. Tenderness stir until the detergent and also sugar are dissolved. Place about 1 tablespoon the detergent systems in a vast clear plastic cup because that each group.


Warming the air inside the bottlePour warm water right into an empty cup until it is around ½-full.

Turn the party over and also dip the opening of the bottle into the laundry detergent to get a movie of detergent extending the rim.

While stop the bottle, slowly push the bottom of the bottle down right into the hot water.

Ask students:

What have the right to you carry out to do the bubble walk down?If students have trouble thinking of one answer, remind them the heating the gas boosted the speed of the molecules, which made the bubble grow. Students should indicate that they must cool the gas in the bottle. This can be done by putting the base of the bottle right into cold water.Cooling the air within the bottlePour cold water into an additional cup until it is around ½-full. If there is tho a bubble on the bottle, progressively push the bottom that the bottle down right into the cold water. If a bubble is no still ~ above the bottle, make an additional bubble by dipping the opening right into detergent and also then pushing the bottom that the bottle into hot water again.

While holding the bottle, slowly push the bottom that the bottle down right into the cold water.


Expected Results

When the party is put in hot water, a bubble creates at the top of the bottle. As soon as the party is put in cold water, the bubble it s okay smaller. It may actually be pushed down right into the bottle.

Have students compare the molecule in solids, liquids, and gases.

Show the molecule model computer animation Comparing Solids, Liquids, and Gases.

Be sure students realize the the molecules displayed are indigenous three various substances all at room temperature. The hard is no melting to end up being a liquid and the fluid is not evaporating to become a gas. The version is not trying to show state changes yet instead display three various substances which space solid, liquid, and gas at room temperature.

Explain the following differences to students:

SolidMolecules are really attracted to one another. Molecules vibrate yet do not relocate past one another. The molecules remain in solved positions due to the fact that of their solid attractions for one another. A solid has actually a identify volume and also a identify shape.LiquidMolecules room attracted to one another. Molecule vibrate but are additionally able to relocate past one another. A liquid has a definite volume however does not have actually a identify shape.GasMolecules room not attractive to each other much at all. Molecules vibrate and are additionally able come move easily past every other. A gas does not have a definite shape or volume. Gas molecule will spread out same to fill any kind of container.

You could use the following example to aid students evaluate how much apart the molecules of a gas are compared to the molecules in a liquid or solid:

Imagine what a tablespoon of water watch like. If that same number of molecules to be a gas, they would certainly be spread out enough to fill up a entirety beach ball. The molecules that consist of a gas are around 100 to 1000 times further apart than the molecule of a heavy or liquid. At room temperature castle are moving at about 1000 miles every hour, however over an extremely short distances.

Draw or task the illustration Solid, Liquid, and Gas.

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Have students usage the projected illustration as a recommendation as they draw a version of solids, liquids, and also gases ~ above their activity sheet. Allude out that the number of motion lines is the exact same for the solid, the liquid, and the gas. This indicates that the different substances are at the exact same temperature. Have students write captions like those listed below to define the molecule in solids, liquids, and gases.

SolidStrong attractionsOrderly arrangementClose togetherDefinite volume and shapeLiquidAttractions no as solid as in solidsRandom arrangementSlightly more apartDefinite volume, no definite shapeGasWeak attractionsRandom arrangementVery far apartNo definite volume or shape