How are redox reactions balanced?

Redox reactions are balanced by ensuring the number of electrons lost in the oxidation half-reaction equals the number gained in the reduction half-reaction.

In a redox reaction, there is always a transfer of electrons from one species to another. The species that loses electrons is oxidised, and the one that gains electrons is reduced. To balance a redox reaction, you need to ensure that the number of electrons lost in the oxidation half-reaction is equal to the number gained in the reduction half-reaction. This is known as the principle of conservation of charge.

The first step in balancing a redox reaction is to identify the oxidation and reduction half-reactions. This can be done by assigning oxidation numbers to each atom in the reaction and identifying which atoms increase or decrease in oxidation number. The species that increases in oxidation number is being oxidised, and the one that decreases is being reduced.

Next, balance the atoms in each half-reaction. This is done by adding coefficients to the species in the reaction. For example, if there are two oxygen atoms on one side of the reaction and only one on the other, you would add a coefficient of 2 to the species with one oxygen atom.

After the atoms are balanced, balance the charges in each half-reaction by adding electrons to the appropriate side. If the half-reaction is oxidation, add electrons to the right side of the equation. If it's reduction, add them to the left side.

Finally, combine the balanced half-reactions. Multiply each half-reaction by a factor that makes the number of electrons in the two half-reactions equal. Then, add the half-reactions together and simplify to get the balanced redox reaction.

Remember, practice makes perfect. Balancing redox reactions can be tricky at first, but with practice, you'll get the hang of it.