Demonstration notebook (paper). This page is a work in progress. Movies will be added as soon as the kids get them made.
I will be doing some demonstrations in class to show you some chemical reactions. You must take notes or drawings as directed by me in class.
You must include the following in your notes.
Some of these demonstrations can be dangerous. Please do not try them at home. If you ever play with chemicals make sure that you know what you are doing and read the safety information.
Below are some of my favorite demonstration I may do for you. They are not in any particular order and I may not even get to them all.
Burning Mg ribbon
2Mg(s) + O2(g) ——> 2MgO(s)
The high temperatures reached during the combustion also allow small amounts of magnesium to react with nitrogen in the air, producing magnesium nitride:
3Mg(s) + N2(g) ——> 2Mg3N2(s)
Bi-Metal strip
Is a metal strip with different metals on each side usually brass and steel. When metals are heated they expand at different rates. These different rates will show as the metal strip curves under the heat. The convex side (outside curve) will expand at a faster rate and therefor become longer or curve around the other metal.
What do you think will happen of this bi-metal strip gets cooled instead of heated?
Mt. Dew raisins
When raisens are added to Mt. Dew they sink. In a little while they will float. Then they will sink. Then they will float... get the picture. Why? Watch the demonstration and figure it out.
Can Crusher (Smasher)
When water is heated to a gas the steam it produces takes up more space than the liquid. The steam (gas) and air escaping from the top of the can creates a lower pressure inside of the can. When the can is cooled down quickly (in the ice bath) the outside air pressure (14.7 psi) pushes in on the can and the can gets crushed until the can is small enough and the pressure is equalized inside and outside of the can. I used a pop can, hot plate and tub of ice. Bill Nye uses a 55 gallon drum, a BBQ grill and a pool! Regarless of size scientific priniples still apply. Air moves from high pressure to low pressure to maintain equilibrium.
You may also notice that water begins to fill the can. Why do you suppose that happens? Think of air pressure and pushing!
This same things happens to your head when you go up in the mountains. Your head has a certain pressure in it here in the valley. when you travel up in elevation there is lower air pressure since there is less air. The air in your head escapes to equalize the pressure. This is when your ears "pop". Air needs to get into your head on the way down.
If you have ever dived in a deep pool or underwater - the opposite effect happens. The outside pressure from the water is greater and it tries to get into your head and you feel pressure pushing on you.
Paint thinner / Styrofoam (water / starch peanuts)
Grain Elevator
We learn about surface area here. When trying to light something like coffee creamer, or lycopodium powder it does not ignite. Much like trying to light a fire by lighting a log with a match. You should use kindling to light a fire and build up to the log. There is more surface area in kindling and thereore more places for oxygen to help feed the fire. Same idea here. The pile of powder leaves very little area for oxygen to help with the combustions plus a smaller peice of material has more surface to burn. Coal fired powerplants use the same theory. Coal is ground up into a powder and blasted into a flame like a jetstream. This ensures all the coal gets burned.
Everyonce in a while silos filed with grains (corn, wheat) explode in this way too. Grain by itself is hard to catch on fire but as you have seen dust is very combustable. Sometimes all it takes is a spark.
P.S. Lycopodium is a moss and the powder are the spores (like seeds).
Goldenrod paper and ammonia
Goldenrod paper has a chemical in it which reacts with Ammonia (NH3). The reaction causes a color change.
Sugar + Sulfuric Acid = stinky snake
This is the one that cleared many classrooms a few years back when I did it... differently. The mixture of sulfuric acid (H2SO4) and sugar (C6H12O6). Creates an exothermic reaction (gives off heat) and creates a black "snake" and wonderful stench!
Mentos Fountain
You know there is CO2 in the soda that is waiting to get out. The addition of Mentos speeds up that process by adding nucleations sites for the CO2 to adhere to. There is a lot of space for the carbon dioxide gas to adhere to and in the process larger bubbles are formed and escape violently out the the top.
Methanol Rocket
Similar to the grain elevator and surface area demonstration above. Liquid methonal is a flammable alcohol however in a gaseous state it has more surface area and is much more combustable. Gasseous fumes can catch on fire to and all it takes is a spark.
Flame tests
Basically anything will burn. It's a matter of at what temperature. We will burn different metals to show you different colors and how fireworks are made.