Redox Reactions and Oxidation States

Redox Reactions

• A redox reaction is a chemical reaction involving the transfer of electrons from one substance to another.
• Also known as oxidation-reduction reactions.

Oxidation

• Loss of one or more electrons by an atom, molecule, or ion.
• Results in an increase in oxidation state (number of electrons lost).
• Example: 2Mg → 2Mg²⁺ + 4e⁻ (magnesium loses electrons to form magnesium ions)

Reduction

• Gain of one or more electrons by an atom, molecule, or ion.
• Results in a decrease in oxidation state (number of electrons gained).
• Example: Cu²⁺ + 2e⁻ → Cu (copper ions gain electrons to form copper)

Redox Couples

• A pair of species that differ by only one electron.
• Example: Fe³⁺ / Fe²⁺, Cu²⁺ / Cu⁺

Oxidizing and Reducing Agents

• Oxidizing agent (oxidizer): a substance that causes oxidation by accepting electrons.
• Reducing agent (reducer): a substance that causes reduction by donating electrons.
• Example: In the reaction between hydrogen and fluorine, hydrogen is the reducing agent and fluorine is the oxidizing agent.

Balancing Redox Equations

• Half-reaction method:
  1. Write two half-reactions: oxidation and reduction.
  2. Balance each half-reaction separately.
  3. Combine the half-reactions to form the overall reaction.
• Example: Balancing the reaction between permanganate and iron(II) in acidic solution.

Redox Reaktioner

• En redox reaktion er en kemisk reaktion, hvor der overføres elektroner fra et stof til et andet.
• Også kendt som oxidation-reduktion reaktioner.

Oxidation

• Tab af en eller flere elektroner af et atom, molekyle eller ion.
• Resulterer i en øgning i oxidationstilstand (antal elektroner tabt).
• Eksempel: 2Mg → 2Mg²⁺ + 4e⁻ (magnesium taber elektroner og danner magnesiumioner).

Reduktion

• Opnåelse af en eller flere elektroner af et atom, molekyle eller ion.
• Resulterer i en nedgang i oxidationstilstand (antal elektroner opnået).
• Eksempel: Cu²⁺ + 2e⁻ → Cu (kopperioner opnår elektroner og danner kopper).

Redox Par

• Et par af arter, der kun adskiller sig ved ét elektron.
• Eksempel: Fe³⁺ / Fe²⁺, Cu²⁺ / Cu⁺.

Oxiderende og Reducerende Agenser

• Oxiderende agens (oxidator): et stof, der forårsager oxidation ved at acceptere elektroner.
• Reducerende agens (reducer): et stof, der forårsager reduktion ved at donere elektroner.
• Eksempel: I reaktionen mellem hydrogen og fluor, er hydrogen reducerende agens og fluor er oxiderende agens.

Balancering af Redox Ligninger

• Halvreaktions-metoden:
  • Skriv to halvreaktioner: oxidation og reduktion.
  • Balancer hver halvreaktion separat.
  • Kombiner halvreaktionerne til at danne den overordnede reaktion.
• Eksempel: Balancering af reaktionen mellem permanganat og jern(II) i sur løsning.