Question

Determine the oxidation number (oxidation state) of each element in the compound CuCO3.

Cu:

C:

O:

Determine the oxidation number of each element in CH4.

C:

H:

Determine the oxidation number of each element in IF.

I:

F:   

Determine the oxidation number of each element in CH2Cl2.

C:

H:

Cl:

Determine the oxidation number of each element in SO2.

S:

O:

Determine the oxidation number of each element in (NH4)2CrO4.

N:

H:

Cr:

O:

Answer 1

CuCO3	Cu	C	O
oxidation number	+2	+4	-2

CH4	C	H
oxidation number	-4	+1
IF	I	F
oxidation number	+1	-1

CH2Cl2	C	H	Cl
oxidation number	0	+1	-1
SO2	S	O
oxidation number	+4	-2
(NH4)2CrO4	N	H	Cr	O
oxidation number	-5	+1	+8	-2

method is; for example (NH4)2CrO4

(NH4)- ,

ox # for H = +1

so ox # for N= -5

let x be ox # for Cr , we know for

(NH4)ion charge = -1 , ox # for O = -2

Total ox # for neutral molecule is zero

then 2(-1) + 4(-2) + x = 0

-2 -6 + x =0

x= +8