00:02
Hi there.
00:03
In this question, we want to determine the oxidation number of x in this polyatomic ion.
00:10
Well, to do that, we need to know a couple of the rules for assigning oxidation numbers.
00:14
One of those is, for an ion, which this is, the oxidation numbers, the sum of the total oxidation numbers, has to add up to the ion charge.
00:41
So for this one, since the ion charge is negative 1, oxidation numbers must add up to negative one.
00:52
The other one that we need to answer this question is that oxygen has an oxidation number of negative 2 except when it isn't a peroxide, but this is not a peroxide.
01:10
So that means oxygen is going to have an oxidation number of negative 2.
01:14
Let's go ahead and assign that and let's figure out what we have here.
01:18
So we have x, whatever its oxidation number is, plus we have four oxygens that each have an oxidation number of negative two, and when we add these together, the sum has to be negative one...