Oxidation — Science definition

Increase in oxidation number; electron loss in a half-reaction.

Where it is taught

In use

Redox describes electron transfer and changes in oxidation number.

Oxidation Numbers & Redox Equations

Questions using oxidation

Problem 1

Find nitrogen oxidation number in NO₃⁻ with O=−2.
Hints

Write the relationship first; substitute with consistent units.

Answer and explanation

5

x−6=−1, x=+5.

Problem 2

Find carbon oxidation number in CO₂ using O=−2.
Hints

List the given quantities, select a relationship, and check units before substituting.

Answer and explanation

4

x−4=0, x=+4.

Problem 3

For Mg+2Ag⁺→Mg²⁺+2Ag, identify oxidation, reduction, both agents and the electron amount per mole of Mg reacted.
Answer and explanation

Mg goes 0→+2 and is oxidized/reducing agent. Ag⁺ goes +1→0 and is reduced/oxidizing agent. One mole Mg transfers two moles electrons, consumed by two moles Ag⁺ in the selected complete account.

Mg goes 0→+2 and is oxidized/reducing agent. Ag⁺ goes +1→0 and is reduced/oxidizing agent. One mole Mg transfers two moles electrons, consumed by two moles Ag⁺ in the selected complete account.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the chemical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 4

Find iron oxidation number in Fe₂O₃ with O=−2.
Hints

Write the relationship first; substitute with consistent units.

Answer and explanation

3

2x−6=0, x=3.

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