Could someone help me with these Oxidation Numbers? I don't know how to do this?

Question

1) Hg2(BrO3)2

2) Cr2(SO4)3

3) CoSeO4

4) Cu2SO3

5) Mn(ClO3)2

6) Fe2(CrO4)3

7) HgCr2O7

8) Co3(PO4)2

We need the oxidation numbers of all the elements in the compound.

Thanks! =)

Answer 1

To solve this question , u must know some important things:

first any compound has a total oxidation number of zero

second , u must know the most commonly used oxidation numbers like oxygen(-2) mercuric (+2)......etc

now  1)Hg +2 , O -2, Br +4

2)Cr +3  O -2 S +6

3)Co +2 , O -8, Se +6

4)Cu +1 , O -2, S +4

5)O -2, Cl -1, Mn +7

6)O -2, Cr +6 , Fe +3

7)O -2, Cr +6 , Hg +2

8)O -2 , P +5, Co +2

Now , how do i get these?

simple, first count the oxidation number of the known things like oxygen, mercury or any ion

this may need some practice till u memorize the common oxidation numbers then this will be very easy

If u know the oxidation numbers of some ions, it will help a lot

like in your last problem no. 8):

we have phosphate ion which has -3 oxidation number so we can get cobalt (+2) and from knowing oxygen is -2 we can get the phosphorus.

try to answer them Agnan by urself