Redox Reactions and Oxidation States

Vocabulary-style flashcards covering the definitions, rules, and agents involved in oxidation-reduction chemistry as per the lecture transcript.

Oxidation State/Oxidation Number

The numerical value of the charge on an atom in a compound.

Oxidation State Rule for Elemental Form

Assign "$0$" to any elemental form of an atom.

Oxidation State Rule for 1st Group

Assign "$+1$" to any member of the 1st Group in a compound.

Oxidation State Rule for 2nd Group

Assign "$+2$" to any member of the 2nd Group in a compound.

Oxidation State Rule for Aluminium

Assign "$+3$" to an aluminium atom in a compound.

Oxidation State Rule for 7th Group

Assign "$-1$" to any member of the 7th Group in a compound.

Oxidation State Rule for Oxygen

Assign "$-2$" to an oxygen atom in a compound.

Oxidation State Rule for Hydrogen (with non-metals)

Assign "$+1$" to a hydrogen atom when bonded with non-metals.

Oxidation State Rule for Hydrogen (with metals)

Assign "$-1$" to a hydrogen atom when bonded with metals.

Redox Reaction

A type of chemical reaction in which both oxidation and reduction take place at the same time.

Reduction (Hydrogen/Oxygen)

Defined by the gain of hydrogen or the loss of oxygen.

Reduction (Electrons/Oxidation State)

Defined by the gain of electrons or a decrease in oxidation state.

Oxidation (Hydrogen/Oxygen)

Defined by the loss of hydrogen or the gain of oxygen.

Oxidation (Electrons/Oxidation State)

Defined by the loss of electrons or an increase in oxidation state.

OIL RIG

A mnemonic for electron transfer where Oxidation Is Loss and Reduction Is Gain.

Identification of Redox Reactions (Elemental)

If an elemental form is present on either side of the reaction, it must be a redox reaction.

Non-Redox Reactions

Acid-Base neutralization, Acid-Carbonate reactions, and Precipitation reactions are examples that can never be redox reactions.

Oxidizing Agent

A chemical substance that helps in oxidation and itself gets reduced; it acts as an electron acceptor.

Potassium manganate (VII)

An oxidizing agent with the formula $KMnO_4$ that changes color from purple to colorless as it reduces to $Mn^{2+}$.

Potassium dichromate (VI)

An oxidizing agent with the formula $K_2Cr_2O_7$ that changes color from orange to green as it reduces to $Cr^{3+}$.

Reducing Agent

A chemical substance that helps in reduction and itself gets oxidized; it acts as an electron donor.

Potassium bromide (as a reducing agent)

Changes from $Br^-$ to $Br_2$, resulting in a color shift from colorless to reddish brown.

Potassium iodide (as a reducing agent)

Changes from $I^-$ to $I_2$, resulting in a color shift from colorless to brown/violet/black.

Displacement Reaction

A type of redox reaction where a more reactive element displaces a less reactive element from its compound.

Disproportionation Reaction

A type of redox reaction in which the same element is both oxidized and reduced, such as in the reaction $Cl_2 + H_2O \rightarrow HCl + HClO$.

Ethanol (Redox character)

Acts as a reducing agent, capable of changing acidified potassium dichromate (VI) from orange to green.

Sulfur dioxide (Redox character)

Acts as a reducing agent that decolourises acidified aqueous potassium manganate (VII).