Purpose
To observe the different expansion rates of dissimilar metals bonded together (differential thermal expansion).

Description
Bonded strips of dissimilar metals (invar steel and brass) bend together when heated or cooled.
NOTE:
-Use fine steel wool to polish up the strip so that students see the different color metals.
Variations: 
Bimetallic coil that has been removed from a dial thermometer.
Battery powered thermostat model with a bimetallic coil.

Pedagogy: Ask the students which direction the strip will bend in the flame, if the strip is turned over.

Equipment
Bimetallic strips
Support Equipment
Bunsen Burner & matches

Purpose
Observing the use of a bimetallic strip in a model of a thermostat.

Description
The bimetallic strip of a thermostat can be heated to close or open a circuit.
Alternate: Battery operated thermostat model, complete with mercury vial.

Equipment
Thermostat model
Support Equipment
Bunsen Burner & matches

Purpose
To demonstrate the thermal expansion of a metal.

Description
When ball and ring are at room temperature, the ball fits through the ring. When ball is heated (use propane burner), it expands so that it will now not fit through the ring.

Equipment
Ball & ring apparatus
Support Equipment
Bunsen Burner & matches

Purpose
To demonstrate the different thermal conductivity rates for different metals

Description
The center of a cross configuration of four different metal rods (copper, brass, aluminum, & iron) is heated to melt wax at the far ends, dropping the strips of wax.
- Before class: Using razor blade provided, cut 4 equal width slices of wax and carefully secure to the ends of rods
- Beginning of class: Bring water in sm. beaker to a boil using the immersion coil. (Water will need ~ min. to come to boil.) 
A small drop of blue food coloring can be added to water for students' observing benefit.
- With Heat Race apparatus on the overhead, add boiling water to the glass dish. Wait ~ min. for the first strip to "drop" (melt) and ~ min. for the last strip to "drop".

Equipment
Heat Race Apparatus, 4 thin strips of wax, food coloring for water?
Support Equipment
Sm. beaker  w/ ~ water, Immersion coil, Overhead projector

Purpose
To demonstrate the transfer of energy via radiation

Description
Light a match at the focus of one parabolic mirror with the heat element (high wattage light bulb) at the other mirror's focus.
NOTE: It is strongly recommended that you practice this demo before trying it out in class.
- Using a rubber band, secure a wood match to the post of mirror w/o light bulb. Make sure that the head of the match is at the focal point of the mirror.
- Mount mirrors, light bulb & match on vertical post rods, 
- Place mounted mirrors 3 to 4 meters apart, facing each other.
- Turn on light bulb and wait ~ min. (assuming all is in alignment!)
Note: Students get a bit antsy during the wait and ~1/2 of them will miss the "bursting into flame" moment.

Equipment
Parabolic mirrors and frames, 300 watt light bulb
Support Equipment
2 vertical mounting rods and (fresh) wood match

Purpose
To observe the unique nature of water: its solid form is less dense than its liquid form.

Description
Drop a pellet of frozen methane into a beaker of liquid methane and watch it sink to the bottom of the beaker.
- Prior to class: pour ~ 500ml of methane into a tall graduated cylinder.
Do not tell students the nature of the liquid - due to its transparent properties, they will assume that it is water.
- Using liquid nitrogen, freeze a pellet of methane in a test tube. 
- After slightly warming up the test tube (to release pellet ) drop pellet into beaker of methane.
- Solid pellet of methane will sink to the bottom of the liquid methane.

Pedagogy: Ask students what they expected, and use demo as a springboard into the unique nature of the relative densities of solid and liquid water.

Recycle used methane back into bottle of methane.

Equipment
Methane, tall graduated cylinder, test tube, test tube holder, beaker of liquid nitrogen

Purpose
To demonstrate room temperature water boiling at a reduced pressure.

Description
Water is observed to boil at room temperature (22 C) when the surrounding air pressure is reduced.
1. Before class: Check mini-vacuum chamber seals for dirt &/or other debris. If necessary, reapply a minimal amount of vacuum grease to gaskets.
2. Place watch glass within mini-vacuum chamber and mini-vacuum chamber on overhead projector. 
3. Pour a small amount of water into watch glass, seal chamber.
3. Attach & turn on vacuum pump. Water should start to boil.
NOTE: Some of the initial boiling may be the pump's removal of the water's dissolved air.
Extension: Wait a bit longer and the boiling water will freeze. 

Equipment
Mini-vacuum chamber, watch glass
Support Equipment
Water, Vacuum pump

Purpose
To observe the gas-to-liquid phase change of air.

Description
Produce Liquid Air in the bottom of a test tube.
Use eye and hand protection!
1. Order liquid nitrogen (LN2) the day prior to the demonstration.
2. Inflate a medium sized balloon and secure opening over the top of a test tube.
3. Pour LN2 into glass beaker. When the boiling has "relaxed" a bit (i.e. beaker comes into thermal equilibrium with contents) - add more LN2 to fill beaker to the top.
4. Place test tube (w/ balloon on top) into LN2 and wait ~ minutes.
5. Remove test tube when balloon is significantly deflated.
6. Have students immediately observe the cloudy liquid (air) within the test tube. Test tube will quickly fog/ frost up - so be quick with the show and tell. As test tube and contents warm up to room temperature, balloon will reinflate.

Equipment
Balloon, Test Tube
Support Equipment
Liquid Nitrogen, large beaker, goggles, gloves

Purpose
To observe the liquid-to-gas phase change of liquid N2.

Description
Blow up balloons the easy way with a small amount of Liquid nitrogen.
1. Order Liquid N2 the day prior to the demonstration.
2. Pour Liquid N2 into a beaker. (Use the opportunity to discuss "boiling" and heat flow.)
3. Using thermal gloves to protect your hands, hold the balloon gingerly at its opening and pour a small amount of Liquid N2 into balloon.
4. Immediately pinch off balloon's opening & shake gently. Balloon will expand as the liquid N2 vaporizes within the balloon.
NOTE:
-You could also use a small funnel to aid in pouring the liquid N2 into the balloon
-Shaking the balloon gently as the liquid N2 vaporizes prevents any given portion of the balloon from freezing. BUT, if you would like a little bang to wake up students - try not shaking up the balloon - or add a little extra LN2.
Caution: ALWAYS wear eye protection!

Equipment
Balloon
Support Equipment
Liquid Nitrogen, thermal gloves, large beaker, goggles, funnel

Purpose
To observe what happens to a liquid when all of the "hotter", faster moving molecules are evaporated away.

Description
A small amount of room temperature water in a watch glass freezes after only ~ minutes when put under a vacuum.
1. Beforehand: Check seals for dirt &/or other debris. Reapply minimal vacuum grease to gaskets only if necessary.
2. Pour a small amount of water into the watch glass & place into the overhead mini-vacuum chamber.
3. Place vacuum chamber on classroom overhead projector & connect up vacuum pump.
4. With overhead projector focused on the water - turn on vacuum pump. There will be some initial boiling due to the release of dissolved air within water. After ~ minutes, water will rapidly & dramatically freeze.

Equipment
Watch Glass, Mini-Vacuum Chamber
Support Equipment
Vacuum Pump, Water, Classroom Overhead Projector

Description
Air within the body of a glass bird cools by the evaporation of water from the bird's beak. Bird's center of mass changes as the changes in the inside air pressure shifts about the fluid within its body.
- Set up bird with a glass of water so that his beak can be lowered into the water. Let bird return to his original upright position.
- Water from beak evaporates, air within bird's upper regions loses heat (temperature decreases) and internal pressure decreases.
- Fluid within bird rises until the bird's center of gravity is above its pivot point and bird fall backs into the glass of water (beak first) for yet another drink of water. (Meanwhile, chambers' air pressures equilibrates, fluid flow back down into lower chamber, bird stands back up, and process begins all over again.)

Equipment
Drinking bird and a glass of water

Description
As a convection tube is heated, dyed water is seen to circulate about the square shaped tube.
(Convection tube is a closed glass square of tubing with an opening at the tube's top.) 
- Add a small amount of food coloring to the top of a closed (square-shaped) tube. 
- Using a propane burner, heat one corner of the tube. Water directly above heated corner will rise.
- Observe the colored portion of the fluid to flow away from heated portion and then down the opposite side of the tube.
(When adding water, fill to top of circular part of tubing. Do not fill to top of opening. There needs to be enough water to allow circulation, but keep in mind that the water will expand when heated.)
Note: The glass tube remains hot for several minutes after the demonstration is completed.

Equipment
Convection tube on stand, food coloring
Support Equipment
Propane, matches

Description
Fill a balloon with air and it is popped by the flame. Fill another balloon with water and it doesn't pop in the flame.

Equipment
One air balloon, one water balloon
Support Equipment
Propane, matches, tongs

Purpose
Observe the change in volume of a container as the temperature of the gas within that container decreases.

Description
Pour liquid nitrogen over an inflated balloon and observe balloon's volume to shrink, let it warm back up to room temperature.
Cautions: Always use eye and hand protection!
1. Arrange for obtaining Liquid N2 the day prior to the demonstration.
2. Place an inflated and tied off medium sized balloon into a large basin.
4. Pour LN2 over the balloon & stir the balloon about. (Stirring allow for a quicker result)
Note: Do not use too much LN2 - the purpose of this demo is to observe volume's dependence on temperature, not to observe a phase change.
5. Use tongs to pick up the deflated balloon and observe the balloon reinflate as it warms up to room temp.

Equipment
Balloon
Support Equipment
Liquid Nitrogen, large beaker, goggles, tongs, basin

Purpose
Observe the change in volume of a container as the temperature of the gas within that container decreases.

Description
- Boil a small amount of water in a can, shake can as heating progresses to insure that air/ vapors within can are thoroughly heated.
- Remove can from flame and immediately seal. Let cool.
Alternate: For a more dramatic effect - use a soda pop can. Heat water within this smaller can; quickly turn can over and place inverted top into a shallow pan of water.

Equipment
Gas Can w/ Lid
Support Equipment
Bunsen Burner, matches, beaker, water

Purpose
Observe the change in pressure of a gas as the volume container decreases.

Description
Using the Boyle's Law Unit, squeeze on syringe and quantitatively observe the increase in pressure while decreasing the volume.

Equipment
Boyle's Law Unit
Support Equipment
Overhead Projector

Purpose
Observe the change in volume of a container (balloon) as the air pressure outside of the container decreases.

Description
Observe the change in volume of an inflated balloon within a bell jar as the pressure of the air within the bell jar (surrounding the balloon) is decreased.
Alternate: Instead of using a balloon - try a marshmallow on a watch glass, or shaving cream in a beaker

Equipment
Balloon
Support Equipment
Large Bell Jar