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Oxidation Numbers Example .txt

Notice how in our three examples, our N differed in every example.

Oxidation Numbers Example .txt

In this one, it was a plus three.

Oxidation Numbers Example .txt

In this one, there was a negative three, and this one was a plus five.

Oxidation Numbers Example .txt

Let's look at four.

Oxidation Numbers Example .txt

In four we have an ionic compound, and that means we have an atom and another molecule.

Oxidation Numbers Example .txt

So this atom, since it's in the second group, gets a plus two.

Oxidation Numbers Example .txt

So this is a plus two.

Oxidation Numbers Example .txt

And we see from this example that each individual guy gets a minus one.

Oxidation Numbers Example .txt

So minus one times two gives us a plus two for this whole guy.

Oxidation Numbers Example .txt

Another way of seeing it a minus two, sorry.

Oxidation Numbers Example .txt

Another way of seeing it would have been to realize that this whole compound that is neutral.

Oxidation Numbers Example .txt

So if this is plus two, this must be minus two.

Oxidation Numbers Example .txt

Now, the individual atoms are the same as this example.

Oxidation Numbers Example .txt

Let's look at this guy.

Oxidation Numbers Example .txt

Well, from this example, we know that each ammonia molecule has a plus one charge.

Oxidation Numbers Example .txt

That means two ammonia molecules will have a plus two charge.

Oxidation Numbers Example .txt

Now, since this entire compound is neutral, that means this guy has to be a minus two.

Oxidation Numbers Example .txt

And now let's assign individual oxation numbers to each atom.

Oxidation Numbers Example .txt

So o perceives s that means we assign to o first.

Oxidation Numbers Example .txt

O gets a negative two.

Oxidation Numbers Example .txt

So negative two times four atoms gives you a negative eight for O.

Oxidation Numbers Example .txt

And since we want an overall negative two on this molecule, this S must have a plus six.

Oxidation Numbers Example .txt

Plus six minus eight gives you a negative two.

Oxidation Numbers Example .txt

Now, we're not going to assign anything to this guy because we already did that in example, too.

Oxidation Numbers Example .txt

Let's look at six.

Oxidation Numbers Example .txt

B a.

Oxidation Numbers Example .txt

So four.

Oxidation Numbers Example .txt

So, once again, BA BA, since it's in a second group, must have a plus two.

Oxidation Numbers Example .txt

So BA gets a plus two.

Oxidation Numbers Example .txt

Let's look at so four.

Oxidation Numbers Example .txt

Now, so four from this example, we know has a negative two.

Oxidation Numbers Example .txt

So this guy must be negative two.

Oxidation Numbers Example .txt

Another way of seeing it would have been to realize that this whole thing is neutral.

Oxidation Numbers Example .txt

So if this is plus two, this might be minus two.

Oxidation Numbers Example .txt

Now, we're not going to assign anything to individual atoms, because we did that in this example.

Oxidation Numbers Example .txt

Let's look at seven.

Oxidation Numbers Example .txt

Now, in seven, we have copper and S, right?

Oxidation Numbers Example .txt

S precedes copper.

Oxidation Numbers Example .txt

So S is in the same group as oxygen.

Oxidation Numbers Example .txt

So S must have a minus two.

Oxidation Numbers Example .txt

So S as a minus two.

Oxidation Numbers Example .txt

Now, this whole compound has a neutral charge.

Oxidation Numbers Example .txt

So if this is minus two, our copper must be plus one each, right?

Oxidation Numbers Example .txt

So this makes our two coppers plus two.

Oxidation Numbers Example .txt

Let's look at this guy.

Oxidation Numbers Example .txt

Now, we already did ammonia.

Oxidation Numbers Example .txt

We know that's.

Oxidation Numbers Example .txt

Plus one.

Oxidation Numbers Example .txt

So this whole thing is plus one.

Oxidation Numbers Example .txt

That means this whole guy must be plus one.

Oxidation Numbers Example .txt

Now this whole guy must be minus one.

Oxidation Numbers Example .txt

And we saw that in this example, it was minus one.

Oxidation Numbers Example .txt

So this whole guy is minus one.

Oxidation Numbers Example .txt

Now let's look at individual atoms.

Oxidation Numbers Example .txt

Individual atoms are the same exact as these two guys.

Oxidation Numbers Example .txt

This must be negative two times three, negative six.

Oxidation Numbers Example .txt

For three oxygen molecules to create a negative one.

Oxidation Numbers Example .txt

Overall, on this molecule, this N must be a plus five.

Oxidation Numbers Example .txt

Plus five, minus six, negative one.

Oxidation Numbers Example .txt

You can check that.

Oxidation Numbers Example .txt

And it works for Ammonium, the same thing that we did here.

Oxidation Numbers Example .txt

This H is assigned first, so it gets a plus one times four, a plus four.

Oxidation Numbers Example .txt

So this guy gets a plus four.

Oxidation Numbers Example .txt

And this end, to create a plus one or charge, must be negative three.

Oxidation Numbers Example .txt

So negative three plus four gives you positive one works.

Oxidation Numbers Example .txt

Let's look at the last one, this guy.

Oxidation Numbers Example .txt

Well, we already know from this example, in this example that so four is negative two.

Oxidation Numbers Example .txt

So four must be negative two.

Oxidation Numbers Example .txt

So our Zn must be plus two because we want a mutual atom.

Oxidation Numbers Example .txt

Now let's look at individual guys.

Oxidation Numbers Example .txt

Well, it's the same thing as we did here.

Oxidation Numbers Example .txt

This guy assigned first to oxygen.

Oxidation Numbers Example .txt

So oxygen gets a negative two, times four, negative eight.

Oxidation Numbers Example .txt

And we want an overall of negative two.

Oxidation Numbers Example .txt

That means our S must get a plus six.

Oxidation Numbers Example .txt

Plus six minus eight gives us a negative two.

Cell diagram .txt

Electrochemical cells can be represented using something called a cell diagram or an electrochemical cell diagram.

Cell diagram .txt

Now, this is simply a simplification of this drawing here, and it looks like this.

Cell diagram .txt

So let's examine our full drawing.

Cell diagram .txt

So within our anode, there's an oxidation reaction.

Cell diagram .txt

So copper solid is oxidized into aqueous copper and it releases electrons.

Cell diagram .txt

Electrons travel in this conductor to this metal bar, the cadmium.

Cell diagram .txt

The cadmium solid.

Cell diagram .txt

And then the electrons react with our aqueous cadmium, forming our solid cadmium.

Cell diagram .txt

So reduction occurs in the cathode and oxidation occurs in the anode.

Cell diagram .txt

Now, this diagram is very tedious to draw.

Cell diagram .txt

We can represent this diagram in a simple way using a cell diagram seen on this side.

Cell diagram .txt

So these guys are equivalent representations.

Cell diagram .txt

Now, the double bar in the middle of the vertical double bar represents our sold bridge.

Cell diagram .txt

The single vertical lines represents our separation of phases.

Cell diagram .txt

For example, we have our solid copper and our aqueous copper.

Cell diagram .txt

So acreage copper sound and solution and beaker one.

Cell diagram .txt

And the solid copper is this electrode bar, the same way that we have the electrode bar this side and acreage copper on this side.

Cell diagram .txt

And this is our separation of phases.

Cell diagram .txt

The same concept on this side.

Cell diagram .txt

This cadmium bar is separated by phases in the solution.

Cell diagram .txt

So we have the ions here and the solid cadmium in the bar the same way that this bar here, this vertical line represents these two phases.

Cell diagram .txt

Now, this is their anode and this is their cathode.

Cell diagram .txt

So the thing on your left is always the anode.

Cell diagram .txt

The thing on your right is always the cathode.