What are the oxidation numbers for ClO-?

1 Answer
Jan 20, 2016

Here's what I got.


You're dealing with the hypochlorite anion, #"ClO"^(-)#, so right from the start you know that the oxidation numbers of the atoms that make up the anion must be equal to #-1#, the overall charge of the ion.

This means that you can write

#ON_"chlorine" + ON_"oxygen" = -1#

Now, oxidation numbers are all about electronegativity. As you know, oxidation numbers are assigned with one concept in mind - that more electronegative atoms will take the bonding electrons from the bond it has with a less electronegative atom.

When oxygen is pairred with a less electronegative atom, its oxidation state is always equal to #color(blue)(-2)#.

In this case, oxygen is indeed more electronegative than chlorine, so you can say that

#ON_"chlorine" + (color(blue)(-2)) = -1#

This means that you have

#ON_"chlorine" = -1 + 2 = color(blue)(+1)#

The oxidation numbers for the atoms that make up the ion are

#stackrel(color(blue)(+1))("Cl") stackrel(color(blue)(-2))("O"^(-))#