How do you use half-equations to represent redox processes?

Half-equations are used to represent redox processes by showing the oxidation or reduction of individual species separately.

In a redox process, there are two simultaneous reactions happening: oxidation and reduction. Oxidation is the loss of electrons, while reduction is the gain of electrons. To represent these processes, we use half-equations. A half-equation is a chemical equation that shows how a species gains or loses electrons.

To write a half-equation, you first identify the species that is being oxidised or reduced. For example, in the reaction between magnesium and oxygen to form magnesium oxide, magnesium is oxidised (loses electrons) and oxygen is reduced (gains electrons). The half-equations would be:

Mg -> Mg2+ + 2e- (Oxidation half-equation)
O2 + 4e- -> 2O2- (Reduction half-equation)

These half-equations show the individual processes of oxidation and reduction. They can be combined to form the overall redox equation.

When writing half-equations, it's important to balance the atoms and charges. In the reduction half-equation above, we added 4 electrons to the left side to balance the charge, and we wrote '2O2-' on the right side to balance the oxygen atoms.

Half-equations are a useful tool in understanding redox processes. They allow us to see the individual steps of oxidation and reduction, and how electrons are transferred in these reactions. By writing and balancing half-equations, you can gain a deeper understanding of the redox process.