Today we've got some really beautiful chemistry for you.

And we're going to show you that science and art are quarrelsome lovers who in

reality can't live without each other. We're going to be making copper one

dioxide. Our first procedure is a rather exotic reduction method. First we've got

here 10 grams of anhydrous copper sulfate which is our copper source.

Remember that the anhydrous powder is a light gray almost white color like this.

If you're using the hydrated salt then you'll need

to adjust the weight accordingly. Next up is our reducing agent. We've

weighed out 6.5 grams of hydroxylamine hydrochloride crystals. This is exotic

and not easily OTC but don't worry we'll be showing you another much easier and

better way later on. And last up is 5 grams of solid sodium

hydroxide. We've got some rats on this to stop it absorbing water from the

atmosphere.

Okay that's the lineup for our first preparation method. We're going to

dissolve the copper sulfate and hydroxylamine in water. Then add the

sodium hydroxide solution. Simple.

First let's make up a solution of the sodium hydroxide. We've got the beaker

and a stir bar set up here on a magnetic stirrer. And we're going to use 40 mils

of water to get the sodium hydroxide into solution.

A little bit of heat generated. Okay we'll cover this up and chill it down now

so it's nice and cool again. Here's our reaction beaker. Use a nice large beaker

as the mixture is going to foam a little bit. Again we've got some strong magnetic

stirrin. Let's start off with 30 mils of water.

And first we'll add the copper sulfate. It's going to give off a bit of heat as it

hits the water, but don't be a wuss. Nice. Let's leave this stirrin for a bit to dissolve.

Add a little more water if you need to.

Okay we've got a nice blue solution now of copper to sulfate.

Let's add our reducing agent,

the hydroxylamine hydrochloride.

As you add it all the color changes, to a green color. This is probably a copper hydroxylamine

complex.

And now let's chill the mixture by placing an ice cube in here.

We're doing this just because the reduction is a little bit exothermic.

Okay let's rock and roll with the chilled sodium hydroxide solution.

There's a dark precipitate, a yellow color, a white precipitate, and some foam produced.

Don't add the sodium hydroxide too fast or the mixture could bubble over.

It soon settles down to form a white precipitate.

And then on adding more sodium hydroxide solution, turns a light orange color.

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We made up another batch of 4 grams of sodium hydroxide in water, and added this in order

to make sure that all the white precipitates had converted to orange.

The exact reaction we're not sure about, but essentially the copper in the two-oxidation

state is being reduced to copper in orange.

The one-oxidation state by the hydroxylamine, which is probably being oxidized to nitrogen

gas.

The sodium hydroxide then precipitates the copper as copper oxide.

Copper hydroxide seems to be very unstable and doesn't exist, immediately forming

the oxide instead.

The beautiful orange color is our hotel forests.

Thats our copper oxide forming.

We leave this turned for a few minutes and make sure that when we take out the upper

and then let the mixture settle.

Let's filter the solid.

We've got a slight problem.

The yellow-orange-colored copper oxide is such a fine precipitate

that it's going straight through our Grade 3 center.

So we got everything back in the original beaker again.

Let's wait and let this settle for a bit.

And then we'll pour off the supernatant liquid.

Okay, let's try again using a paper filter this time.

A little bit coming through, but much better now.

We washed the precipitate with water and then dried it on the pump.

But this is what we got.

On exposure to air, the outer layer of the product very quickly turns black.

It's being oxidized to black-colored copper dioxide.

Doesn't look great, does it?

What we found is that the product from the reduction depends on the reducing agent.

Use a strong agent like hydroxylamine or hydrazine,

and you end up with a very, very fine precipitate.

You can't tell it's fine because the color is closer to a yellow than a red when it forms.

And the finer the precipitate, the more easily it oxidizes in the air.

This is more like dog poo than copper dioxide.

So let's try a Plan B approach.

Okay, this time we're going to do it differently.

We'll whiz through the preparation a bit faster

because you're probably bored of watching us mix ship together by now.

Here's our four ingredients for the second preparation we tried out.

From left to right.

First up, copper to sulfate again.

And again we're using 10 grams of the anhydrous salt.

Now the reducing agent.

This time we're going to use 10 grams of sodium bisulfite,

which is a fine white powder.

Next, 20 grams of sodium chloride crystal.

And finally, 8 grams of sodium hydroxide,

which we've got covered up to protect it as before.

Let's see if this motley crew of assorted chemicals can do the job better.

First let's make up the sodium hydroxide.

Using just over 30 mils of water.

We'll chill this down as before so it's nice and cold.

A nice big beaker again.

Note this mixture can also foam up as well.

First of all, we add about 100 mils of boiling hot water to the beaker.

Let's get stirring.

Okay, let's dissolve the copper sulfate.

And then add the sodium chloride.

That's looking nice.

As the sodium chloride goes in you can see a color change to a light green color.

This is the copper-chloral complex forming in solution.

And now let's carefully add the sodium bisulfite to the mixture.

Do this slowly.

Wow!

It's now turned a red-orange color.

Now our final ingredient.

Let's add the sodium hydroxide solution.

Beautiful!

This time you can see the color is more like an orange-red.

We'll leave it stirring for a few minutes.

And then as before we'll let the mixture settle a bit before we try to filter.

This time we'll go straight to paper.

Not too much coming through the filter.

We washed the solid on the filter with 2 portions of 20 mils of absolute ethanol in an attempt

to get as much water out as possible.

Here's what we got. It's a semi-dry paste still at the moment, but it is a beautiful intense orange color and doesn't seem to be oxidizing in the air as you can see.

It dries out fairly quickly leaving a fine orange powder.

And we ended up with around 3 grams of product, which is a 67% yield on starting copper sulfate. So we definitely recommend this as a better preparation method.

The filtered paper looks pretty funky.

Let's see what happens when we add a few drops of concentrated nitric acid.

Brown nitrogen dioxide is produced and the copper is oxidized to blue copper to nitrate.

Very pretty.

Let's add some 15% hydrogen peroxide now.

The copper oxide catalyses the decomposition of the hydrogen peroxide forming oxygen, but at the same time some of the orange copper oxide is oxidized to black colored copper oxide, forming a dark brown color.

The colors are beautiful.

So we decided we would try out a little experiment using another filtered paper which we coated with some of the copper oxide.

Enjoy the show!

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Thank you.

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Thank you.