Oxidation Number

The maximum oxidation state of an element depends on its group number and the number of valence electrons. For example, manganese (Mn) in Group 7 of the periodic table has an oxidation state of in (permanganate ion). Thus, is the maximum oxidation state.

Understanding Oxidation Numbers in Peroxides:
In most compounds, oxygen has an oxidation number of -2. However, in peroxides, oxygen atoms are bonded to each other in an O–O single bond, which affects their oxidation state.

Example of a peroxide:
Hydrogen peroxide (H₂O₂)

Step-by-step calculation in H₂O₂:
Let the oxidation number of each oxygen be x.
Hydrogen has an oxidation number of +1.
The overall charge of the molecule is 0.
So the equation becomes:
(2 × +1) + (2 × x) = 0 → 2 + 2x = 0 → x = -1

Final Answer: Option 1: -1

Step 1: Understand the chemical formula.
Sulfuric acid is represented as H₂SO₄.

Step 2: Know the oxidation numbers of known elements:
- Hydrogen (H) has an oxidation number of +1.
- Oxygen (O) has an oxidation number of -2.

Step 3: Let the oxidation number of sulfur (S) be x.
Total oxidation number of the molecule is 0 (since H₂SO₄ is a neutral compound).

Step 4: Write the oxidation number equation:
(2 × +1) + (1 × x) + (4 × -2) = 0
⇒ 2 + x - 8 = 0
⇒ x = 6

Final Answer: +6

In , hydrogen has an oxidation state of +1, oxygen has an oxidation state of -2. Let the oxidation state of sulfur be . The sum of oxidation states in a neutral compound must be zero. Therefore: Thus, the oxidation state of sulfur in is +6.

Concept: The sum of oxidation states of all atoms in a neutral molecule is zero. Standard oxidation numbers: - Hydrogen - Oxygen
Step 1: {Assign oxidation numbers.} Let the oxidation state of phosphorus be . For : Hydrogen contribution: Oxygen contribution:
Step 2: {Apply the oxidation state rule.}

Concept: The oxidation state of an element is calculated by assuming:

• Hydrogen =
• Oxygen =
• Sum of oxidation states in a neutral compound =

Step 1: {Find oxidation state of P in .} Let oxidation state of phosphorus =
Step 2: {Find oxidation state of P in .} Let oxidation state of phosphorus =
Step 3: {Conclusion.}

Concept: The oxidation state represents the hypothetical charge assigned to an atom in a compound assuming complete transfer of electrons. For oxygen, the common oxidation states are:

• in most oxides (e.g., )
• in peroxides (e.g., , )
• in superoxides

Peroxides contain an O–O single bond, which changes the oxidation state of oxygen.
Step 1: {Consider hydrogen peroxide as an example.} The oxidation state of hydrogen is . Let the oxidation state of oxygen be .
Step 2: {Apply the rule that total oxidation state equals zero for a neutral molecule.}
Step 3: {State the result.} Thus, the oxidation state of oxygen in peroxides is