* Oxygen: Oxygen usually has an oxidation state of -2, except in peroxides (like O2²⁻) where it has an oxidation state of -1.
* Hydrogen: Hydrogen usually has an oxidation state of +1.
* Overall Charge: The peroxoborate ion has a charge of -1.
Let's break down the oxidation states:
* Two peroxide groups (O2²⁻): Each peroxide group has two oxygen atoms with an oxidation state of -1, giving a total of -2 per peroxide group. Since there are two peroxide groups, the total contribution from peroxide oxygen is -4.
* Two hydroxide groups (OH⁻): Each hydroxide group has one oxygen atom with an oxidation state of -2 and one hydrogen atom with an oxidation state of +1. This gives a net oxidation state of -1 per hydroxide group, and a total of -2 for both.
Now, let's represent the oxidation state of boron as 'x':
x + (-4) + (-2) = -1
Solving for x:
x = -1 + 4 + 2 = +5
Therefore, the oxidation state of boron in the peroxoborate ion is +5.
