Question

Assign oxidation numbers to each atom in the following compounds or ions: a. HFb. C/4c. H₂0d. Pl3e. CS₂f. Na₂O₂g.H₂CO3h. NO 2i. SO2-4Deforming the oxidation numbers for iron oxide Fe-On (Recall that oxidation numbers are integers)

Answer 1

Some oxidation number rules

1) The oxidation number of a free element is always 0. The atoms in He and N2, for example, have oxidation numbers of 0.

2) The usual oxidation number of hydrogen is +1.

3 The oxidation number of oxygen in compounds is usually -2. Exceptions include OF2 because F is more electronegative than O, and BaO2, due to the structure of the peroxide ion, which is [O-O]2-.

a) HF, H = +1 F = -1

b)

c) H₂0, H = +1 O = -2

d) Pl3, P = +3 I = -1

e) CS₂, C = +4 S = -2

f) Na₂O₂, Na = +1 O = -1

g) H₂CO3 H = +1 C =+4 O =-2

h) NO2 N = +2 O = -2

i) SO2-4 S =+6 O = -2