Ch 6Redox Reactions — Class 11 Chemistry, concept-first.

Redox is a short form for the two words 'oxidation' and 'reduction' occurring together in one reaction. Redox reactions are not a rare, specialised topic -- they run through everyday life.

Classically, oxidation was defined narrowly as combination with oxygen. Carbon burning, C(s) + O2(g) → CO2(g), and magnesium burning, 2Mg + O2 → 2MgO(s), are both oxidations by this definition, since…

The classical, substance-based definitions of Section 6.1.1 can all be re-derived from a single, more fundamental idea: oxidation is loss of electrons, and reduction is gain of electrons.

The electron-transfer picture in Section 6.1.2 describes redox reactions cleanly when the species involved are genuinely ionic, with a complete transfer of one or more whole electrons from one species…

Eight rules fix the oxidation number of any atom in any compound or ion. Rule 1: an atom of an element in its free, uncombined state has oxidation number zero -- every atom in H2, Cl2, O3, S8, P4, or…

Stock notation, named after the German chemist Alfred Stock, is a compact way of showing an element's oxidation number directly inside a compound's formula: the oxidation number is written as a Roman…

With the idea of oxidation number in hand, oxidation, reduction, oxidising agent and reducing agent can all be redefined in one general way that covers both ionic and covalent redox reactions.

Once a reaction has been confirmed as redox and its oxidant and reductant identified, the next task is to write a correctly BALANCED equation for it -- one where the number of atoms of every element,…

The oxidation number method balances a redox equation in five steps. Step I: write the unbalanced (skeletal) equation and balance every atom EXCEPT hydrogen and oxygen first; then identify which atoms…

The ion-electron (half-reaction) method balances a redox equation in seven steps by keeping the oxidation process and the reduction process completely separate until the very end.

Section 6.1.1 already noted that a displacement reaction is a kind of redox reaction; this section develops that link further using Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s) as the running example, showing…

The standard electrode potential, written , is the electrode potential measured under one fixed, agreed set of conditions: every species taking part in the electrode reaction at unit concentration, an…