What is a redox reaction?
1st definition: Oxidation is gain of oxygen. Reduction is loss of oxygen
2nd definition: Oxidation is loss of hydrogen. Reduction is gain of hydrogen
Modern definition: Oxidation is loss of electrons. Reduction is gain of electrons.
“The Elephant Toothpaste experiment earned its name from the foamy byproduct of the rapid decomposition of hydrogen peroxide. Mixing yeast with hydrogen peroxide catalyzes its decomposition into water and oxygen gas via an exothermic reaction. Adding some dish soap causes the explosion of foam!”
This demonstration is based on the decomposition of hydrogen peroxide into water and oxygen gas.
Reactions like these that are both oxidations and reductions are known as disproportionation reactions:
2 H2O2(aq) -> 2 H2O(l) + O2(g)
Left on its own at room temperature, this reaction happens at a rate so slow that, for practical purposes, it may as well not even exist. A catalyst is added to speed things along.
What is reduction potential?
Think of a compound as being like a large magnet. A large magnet attracts nails more strongly, and holds them more tightly, than a small magnet. Similarly, a compound with a large (positive) reduction potential attracts electrons more strongly than a small (or even a negative) reduction potential.
Myth: Redox reactions are different from other chemical reactions, like combustion, decomposition, replacement, etc.
Fact: Single-replacement rxns and combustion rxns are always redox. Other types are sometimes redox.
Sodium and fluorine bonding ionically to form sodium fluoride. Sodium loses its outer electron to give it a stable electron configuration, and this electron enters the fluorine atom exothermically. The oppositely charged ions are then attracted to each other. The sodium is oxidized, and the fluorine is reduced.
“LEO the lion says GER”
Loss of Electrons is Oxidation, Gain of Electrons is Reduction.
“RED CAT” and “AN OX”
Reduction occurs at the Cathode, and the Anode is for Oxidation
Oxidation and reduction overview