This work was created by Dr Jamie Love and licensed under a Creative Commons Attribution-ShareAlike 4.0 International License Creative Commons Licence.

PRINCIPLES OF ALCHEMY

EARTH

Can we turn a compound into an element?

Yes we can, but it will require some different chemicals. Get a small bottle of hydrogen peroxide from my box of stuff. You can get hydrogen peroxide from any drug store because people often use it to clean wounds. It is usually a few percent of hydrogen peroxide in water.

Is it safe?

Well, don't drink it or get it in your eyes. That would not be safe. But you can pour a small amount into the palm of your hand. Go ahead.

Pour the hydrogen peroxide into my palm?

Yes, just a few drops are all you need. Your hand will be OK. Go ahead and see what happens.

It's bubbling! Tiny bubbles.

Yes. Hydrogen peroxide (H2O2) is not very stable. When you take it out of the bottle and put it in your hand the hydrogen peroxide decomposes rapidly.

What do you mean by it "decomposes"?

The compound, hydrogen peroxide (H2O2) breaks up into the elemental molecules of oxygen (O2) and the compound molecules of water (H2O). Like this
H2O2 ------> O2 + H2O
(A balanced equation would be 4H2O2 ------> 2O2 + 4H2O, but that is something we will discuss later.)

So, these tiny bubbles are the gas oxygen (O2)?

Yes. Water is also formed but you don't notice it.

You know, there's a lot of Alchemy you can't see. Right?

Right. But that makes for some pretty boring experiments.

How about one final experiment to show you a really impressive chemical change.

OK. What?

Get some "tincture of iodine" from the cabinet. It is use to clean wounds so you can get it from the same place you got the hydrogen peroxide.

OK. Should I put some in my hand?

No. Put a few drops of the iodine in a glass and then pour water into the glass until it is about half full.

OK. Done. Most of the color from the iodine is gone now.

Yes. I can't see any at all.
Now add a few grains of cornstarch and give it a stir.

It's turning blue! Wow. How? Why?

The iodine and the starch form a complex compound that is blue.
Iodine is an element. Starch is a compound called a carbohydrate (because it is made of carbons, along with oxygen and hydrogen like water). When you combine them they bond to each other and the new compound is blue!

I like that. Very nice. But what is it? Can you write an equation that explains this?

No, I can't. Even the 20th century Alchemists are not really sure why this blue stuff forms or exactly what it is!

But, it's such a simple and easy experiment.

Yes, but hard to explain.

So it's a useless chemical change?

No, not at all. It's very useful.
This is a common test for starch. The more starch you add the more blue it gets. No one has come up with a good explanation of it, but we Alchemists use it all the time to test for the presence of carbohydrates.

Let me get this straight. You have no idea how it works? No idea at all? But you still use it to test for carbohydrates?

That's right. And you can too. Make up a batch of iodine in water. Dilute the iodine until you can barely see any color. Mix it real good and pour some "iodized water" into a series of glasses. You can make as many glasses of iodine as you like. You can make as many glasses of iodine as you like. Then to each one you can add something to it. If the solution turns blue....

... then that something you added must contain starch!

Right. The more blue it gets, the more carbohydrates it has in it.

What would happen if I put a piece of apple into iodine?

Try it and find out.

What would happen if I put a piece of cereal into iodine?

Try it and find out.

What would happen if I put a piece of string into iodine?

Try it and find out.

What would happen if I put a goldfish into iodine?

Ah, don't try that. The fish would not like being blue. It would probably die!
The point here is that you can use this iodine to test for the presence of a carbohydrate.

If it has carbohydrate the water will turn blue.

Yes. Or the water may stay clear but the thing you put in it will turn blue. It's that surface effect like with the copper wire. Sometimes the chemical change only occurs on the surface and you would need to chop up the material to let all the carbohydrate out. That's why it is good to start the experiment with cornstarch. The cornstarch is finely chopped up carbohydrate.

You know, I could do a whole bunch of experiments to test for starch. I could test lots of things. I could make, say five glasses of iodine, and then add different amounts to cornstarch to each. Then I would have a bunch of glasses, some more blue than others.

That's right. Try putting just one grain of starch into one glass, two grains into another, and so on.

I bet I would end up with a series of glasses each more blue than the previous one because it would have more starch in each. More starch makes more blue.

That's right. You can even begin to compare the glasses to figure out how much starch is in something else.

What do you mean?

Well, if you had those five glasses with different amounts of cornstarch in each, you would have a series of blue glasses. Each glass would have a known amount of cornstarch because you know how much you added.

So?

So, you could use those five glasses for a comparison. If you ground up a bit of cereal and put it into a sixth glass of iodine water, it would turn blue because of the starch in the cereal.

Yeah? So?

So, you could compare the "blueness" of the glass containing the cereal, with the "blueness" of the other five glasses.

Oh, I see. If I found a glass which is just as blue as the glass with the cereal, I would know the cereal has as much carbohydrate as the amount I put in that glass. Right?

Right! We call the five glasses with known amounts of starch the "standards", because we use them as a "standard" amount of blue for each amount of cornstarch. You know how much of the starch is in each standard because you put a known amount in each.

I see. That way I can figure out if something contains starch (which is a carbohydrate) and even how much it contains.

Right.
This is an example of an "assay". Alchemists do assays all the time. An assay is a test for a substance and some assays, like this one, can even tell you how much is present.

I'll make a lot of iodine water and test a lot of things.

Good idea. But be sure you get permission and clean up when you are done.


This work was created by Dr Jamie Love and licensed under a Creative Commons Attribution-ShareAlike 4.0 International License Creative Commons Licence.