Redox Reactions and Oxidation States

The branch of chemistry that studies the relationship between chemical reactions and electricity.

Chemical reactions involving the transfer of electrons. They involve both oxidation and reduction.

A process that involves the addition of oxygen or the removal of hydrogen. It's the "loss" of electrons.

A process that involves the addition of hydrogen or the removal of oxygen. It's the "gain" of electrons.

Reactions that occur without needing an external energy source. They release energy spontaneously.

In redox reactions, the total loss of electrons by the species undergoing oxidation must equal the total gain of electrons by the species undergoing reduction.

A reaction that releases energy and occurs without needing an external energy source.

Chemical reactions involving the transfer of electrons between reacting species. One substance is oxidized, while the other is reduced. These are also known as redox reactions.

A chemical component in a reaction that gains electrons, becoming reduced.

In its pure form, an element has an oxidation state of zero.

The oxidation state of a single charged atom is the same as its charge.

The sum of the oxidation states of all atoms in a neutral molecule equals zero.

The sum of the oxidation states of all atoms in a polyatomic ion equals the charge of the ion.

In most compounds, hydrogen carries an oxidation state of +1. But in metal hydrides, it's -1.

An electrochemical cell where a spontaneous chemical reaction produces an electric current.

A setup with two half-cells connected by a salt bridge. Each half-cell contains an electrode in a solution of its own salt, and they are connected by an external wire.

A process where a substance loses electrons, often by gaining oxygen or losing hydrogen. It happens at the anode.

A process where a substance gains electrons, often by gaining hydrogen or losing oxygen. It happens at the cathode.

A chemical reaction that occurs without the need for external energy input. It releases energy.

The electrode where oxidation occurs, losing electrons and releasing positive ions into the solution.

The electrode where reduction occurs, gaining electrons and accepting positive ions from the solution.

Zn metal is oxidized, losing electrons and forming Zn²⁺ ions, which dissolve in the solution.

Cu²⁺ ions in the solution gain electrons and are deposited as solid Cu atoms on the electrode.

The overall chemical reaction in a Daniel Cell, combining the oxidation and reduction half-reactions.