Final answer:
In carbon monoxide (CO), the carbon (C) has an oxidation number of +2 while the oxygen (O) has an oxidation number of -2. These oxidation states balance each other out resulting in a molecule with a net charge of zero.
Step-by-step explanation:
The oxidation number of an atom is a figure that represents the total number of electrons that an atom either gains or loses in a chemical reaction. In the molecule carbon monoxide (CO), we have a pair of elements, carbon (C) and oxygen (O). To determine the oxidation number for each, we use the concept that the sum of the oxidation numbers must equal the charge of the molecule, which is neutral in this case.
Generally, oxygen has an oxidation number of -2. Since we have only one oxygen atom, it maintains this oxidation number in carbon monoxide. As the compound must be electrically neutral, and oxygen is -2, the carbon must have an oxidation number that balances this, to sum up to zero. Therefore, we assign the carbon an oxidation number of +2 and the oxygen the usual -2, resulting in a molecule with a net charge of zero. It's important to understand that assigning oxidation numbers is based on a set of rules, one of which is that the sum of oxidation numbers in a neutral compound must be zero.
Carbon in CO is therefore the reducing agent, since it contains the element that is oxidized when these two react with other substances, often taking electrons from the other reactant which is then said to be reduced.