Question

Use oxidation numbers to identify the OA and RA, and to balance the following equation in acidic conditions.

Answer 1

Oxidation number, also called Oxidation State, the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom. The iron ion Fe3+, for example, has an oxidation number of +3 because it can acquire three electrons to form a chemical bond, while the oxygen ion O2− has an oxidation number of −2 because it can donate two electrons. 

Example:

The oxidation number of P increased, and the oxidation number of N decreased. Therefore, the oxidizing agent (OA) is NO3- and the reducing agent (RA) is P4.

In acidic conditions: