Friday afternoon.

Lab class.

Gary - Pure/Impure mixtures.

It was a nice session, and he did some thinking on how he would teach it. And I think Gary did quite well.

He also had some good demonstrations with the Hoffman's experiment using the tube and electrolysis of water to produce Hydrogen and Oxygen gas.

Hydrogen gas ignition and it going "pop" is so cool hehehe
The oxygen didn't work because it wasn't fast enough, but even so, it was still pretty good.

Dan - Particle theory of gas

It didn't go so well for Dan.....
He used the cartesian diver to demonstrate change of pressure in gasses.
But it might have been way too deep for the year 7 and 8 level that it is required for.

As a addition, Tony did some demonstrations for us, as tricks for getting things.

If you can't get oxygen gas, then make it.
All you have to do is get peroxide, which is easy, because it is H2O2 (where the numbers are subscript) and degredation of peroxide produces oxygen gas and water. All you have to do is mix it with manganese oxide, and it should bubble out oxygen.

The other one was the Carbon Snake.
It's one of the most cool demonstrations that you can do.
It has some safety concerns associated, but nothing too major.

Ingredients:
Sugar (50g)
Water
Concentrated Sulphuric Acid (~10M) (50mL)

Equipment:
Tall beaker (250mL, but a long tall, not a regular one)
Stirrer
Lab tray
Fume hood

Method:

All beakers should be on the Lab tray in the Fume hood.
1) Put sugar into tall beaker
2) Moisten the sugar with just enough water to make contents *damp*. Not wet. Mix well.
3) Pour the Sulphuric acid in and mix quickly.
4) Continue to mix until the solution turns black.
5) Step back and watch.

What should happen is the solution will turn back, and steam will generate from the surface.
After a few seconds/minutes (depends on acid concentration and water content), the solution will actually start to foam, and a "snake" will grow and lengthen out of the beaker. You need a small diameter beaker so it "snakes" otherwise a fat beaker makes it look not as impressive.
The snake will continue to grow for quite a bit depending on the sugar,acid, water ratios. The black foam will then cool and turn into disintergratable carbon powder foam.

What is happening?

Sugar is made as a carbohydrate
C(x)H(y)O(z) where x, y, z are numbers.
There is different sugars thus different numbers of carbon, hydrogen and oxygen molecules.

Sulfuric acid
H2S04.

The reaction causes the sugar to lose water molecules as sulphuric acid is a dehydrator. This in turn causes water to be produced, along with hydrogen gas, and carbon.
But the reaction is also generating a lot of heat, so the water is turned into steam.
This steam them "cooks" the carbon foam, and pushes with steam power, the foam out of the beaker as it is being formed.
It is quite a cool demonstration for chemical reactions, and breaking compounds/mixtures into basic elements.