00:01
Hello.
00:02
In this question, we are asked to determine the oxidation number of chlorine in each of these compounds.
00:15
Okay, so our first one, we have sodium chloride.
00:22
To answer this one, we're going to use the rule that says the oxidation number in an ionic compound, the oxidation number is the same as the ion charge.
00:39
So in nacl, the sodium is in group one of the periodic table, so it has a single positive charge, and chlorine is in group 7a, so when it forms an ion, it has a single negative charge.
00:53
Therefore, the oxidation number of the chlorine in this compound is simply negative 1.
01:02
In letter b, we have mgclo4 ,2.
01:10
Well, clo4 is the chloride ion, and it has a single negative charge.
01:19
Well, we know that for a polyatomic ion, the oxidation numbers add up to the charge of that polyatomic ion.
01:39
We also know that oxygen, unless it's in a peroxide, has an oxidation number of negative two.
01:55
So if the oxygen is negative two here, and there are four of those, four times negative negative 2 plus whatever the chlorine's oxidation number is has to add up to the charge of the polyatomic ion, which is negative 1.
02:17
So what we have here is x minus 8 equals negative 1.
02:23
Adding 8 to each side, we see that x equals positive 7...