Question 1

How is carbon's oxidation number calculated in methane?

Accepted Answer

Hydrogen has oxidation number +1, so each of the four C-H bonds contributes −1 to carbon. Carbon in CH₄ therefore has oxidation number −4, which makes methane a strongly reduced organic compound.

Question 2

Why is carbon −2 in methanol?

Accepted Answer

Three C-H bonds contribute −3 and the single C-O bond contributes +1 because oxygen attracts the assigned bonding electrons. Thus −3 + 1 = −2. Carbon is approximately sp³-hybridized in methanol.

Question 3

Why does carbon have oxidation number +4 in carbon dioxide?

Accepted Answer

CO₂ is linear, O=C=O. Each double C=O bond contributes +2 to carbon under formal electron assignment, so the total is +2 + +2 = +4.

Question 4

Does reversing the reaction arrow automatically reduce carbon dioxide?

Accepted Answer

No. Reversing an arrow does not by itself describe a reaction. A suitable reducing agent must donate electrons or hydrogen so that the oxidation number of carbon decreases.

Question 5

What is the contribution of a carbon-carbon bond?

Accepted Answer

Both carbon atoms have the same electronegativity, so the bonding electrons are divided equally. A C-C bond therefore contributes zero to the oxidation numbers of both carbon atoms.

Organic Redox 3D: Track Carbon's Oxidation Number

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