CHEM 3A: Redox Reactions

Comprehensive vocabulary flashcards covering the key concepts, rules for assigning oxidation numbers, mnemonics, and reaction types from the Unit 2 Redox Reactions lecture in Chem 3A.

Redox Reactions

Stands for 'Reduction - Oxidation Reactions': two simultaneous processes in which electron(s) are transferred from one reactant to another.

Oxidation

The chemical process involving the loss of electrons, resulting in an increase in oxidation number.

Reduction

The chemical process involving the gain of electrons, resulting in a decrease in oxidation number.

LEO says GER

A mnemonic for redox reactions: Loss of Electrons is Oxidation, Gain of Electrons is Reduction.

OIL RIG

A mnemonic for redox reactions: Oxidation Is Loss of electrons, Reduction Is Gain of electrons.

Reducing Agent

The reactant that loses electrons, becomes more positive, and experiences an increase in oxidation number.

Oxidizing Agent

The reactant that gains electrons, becomes more negative, and experiences a decrease in oxidation number.

Oxidation Number (Oxidation State)

The charge an element in a compound would possess if the compound were completely ionic.

Oxidation Number of Free Elements (Rule 1)

If an element is alone without a listed charge, its oxidation number is $0$ (e.g., $N_2(g)$ and $Na(s)$).

Oxidation Number of Monatomic Ions (Rule 2)

The oxidation number of an ion equals its charge (e.g., $Na$ is $+1$ in $NaCl$, and $Cu^{2+}(aq)$ is $+2$).

Oxidation State Rules for Hydrogen, Oxygen, and Fluorine (Rule 3)

$H$ prefers $+1$ (with nonmetals) or $-1$ (with metals); $O$ prefers $-2$ unless bound to $F$ or itself; $F$ prefers $-1$.

Total Oxidation Number Rule (Rule 4)

The total oxidation number of all atoms in a neutral molecule or polyatomic ion must equal its overall charge.

Identifying Redox Reactions

A criterion stating that ONLY in redox reactions will the oxidation numbers for two elements change: the reducing agent's oxidation number increases, and the oxidizing agent's oxidation number decreases.

Single Displacement Reaction

A type of redox reaction in which one element replaces another element in a compound ($A + BC \rightarrow AC + B$).

Metals in Acid Solutions

A single displacement reaction where a metal reacts with an acid solution to produce an aqueous ionic compound and hydrogen gas ($H_2(g)$), such as $Mg(s) + 2HCl(aq) \rightarrow MgCl_2(aq) + H_2(g)$.

Group 1 Metal in Water

A single displacement reaction where an alkali metal reacts with water to produce a metal hydroxide and hydrogen gas ($H_2(g)$), such as $2Na(s) + 2H_2O(l) \rightarrow 2NaOH(aq) + H_2(g)$.

Combustion Reactions

A type of redox reaction that emits a significant amount of energy; the combustion of hydrocarbons (containing C, H, and sometimes O) always forms $CO_2(g)$ and $H_2O(l)$.