oxidation states (1 Viewer)

[okhan90]

heyy i was just wondering how to figure out the oxidation state of a compound such as umm.. like juz say

H2SO4

thanxx

 

[Forbidden.]

The total charge on H₂SO₄ is neutral.

Or do you wanna find the oxidation state of the 2H⁺ or SO₄^2-

 

[okhan90]

lol neutral :S... i dont kno we did it in class before something like

H2SO4 = 0

then valency of h x 2 + 4(valency of S and O) = 0 something like that i fink but im not sure

 

[Partisan]

The oxidation number (O.N.) of a monatomic ion is equal to the charge on the ion.

e.g

O.N. of H⁺ = +1
O.N. of H⁺ = 2 x +1

The sum of the oxidation numbers of all atoms in a neutral molecule is zero.
Sum of O.N. of H₂SO₄ = 0 as there is no charge.

e.g if you want to find the O.N. of either ion it's just simple linear algebra.

O.N. of H⁺ in H₂SO₄ is 2x - 2 = 0, solve for x.
(- 2 because O.N. & charge for SO₄^2- is - 2)
(2x because 2H⁺ is diatomic)

O.N. of SO₄^2- in H₂SO₄ is 2 + x = 0, solve for x.

 

[vulgarfraction]

summary:

sum of oxidation numbers for all neutral atoms/molecules is 0
sum of oxidation numbers for ion is valency of the ion

O is -2 (except for in H2O2, where it is 1)
H is always +1

hope that helps

(so in H2SO4: H is +1, O is -2, total is 0 :. S is 6.)

 

[brenton1987]

(2x because 2H⁺ is diatomic)

No it isnt.
2H⁺ is 2 monatomic ions. H₂ is diatomic.

H is always +1

Except in metal hydrides when it is -1.
eg. LiAlH₄ which has Li+1, Al+3 and H-1.

 

[vulgarfraction]

I knew there was an exception.