Iron ( \(\mathrm{Fe})\) can combine with oxygen \((\mathrm{O})\) to produce any one of the three different iron oxides: \(\mathrm{FeO}, \mathrm{Fe}_2 \mathrm{O}_3\), and \(\mathrm{Fe}_3 \mathrm{O}_4\). Of the three oxides, \(\mathrm{FeO}\) is the most unstable. If \(\mathrm{FeO}\) is exposed to air, it forms \(\mathrm{Fe}_2 \mathrm{O}_3\). Which equation correctly describes this reaction? A. \(\mathrm{FeO}+\mathrm{O}_2 \rightarrow \mathrm{Fe}_2 \mathrm{O}_3\) B. \(\mathrm{FeO}+\mathrm{O}_2 \rightarrow 2 \mathrm{Fe}_2 \mathrm{O}_3\) C. \(2 \mathrm{FeO}+\mathrm{O}_2 \rightarrow \mathrm{Fe}_2 \mathrm{O}_3\) D. \(4 \mathrm{FeO}+\mathrm{O}_2 \rightarrow 2 \mathrm{Fe}_2 \mathrm{O}_3\)

Chemical reactions are processes in which substances, known as reactants, are transformed into different substances called products. These transformations occur because of the rearrangement of atoms.
For the given exercise, the reactants are iron(II) oxide (FeO) and oxygen (O₂). They combine to form iron(III) oxide (Fe₂O₃), a different compound.
When balancing chemical equations, it's essential to ensure that the number of each type of atom is the same on both the reactant and product sides. This follows the Law of Conservation of Mass, which states that matter cannot be created or destroyed in a chemical reaction.
In the example provided, we started with the unbalanced equation: \(FeO + O_2 \rightarrow Fe_2O_3\). By balancing the atoms step by step, we finally arrived at the balanced equation: \(4FeO + O_2 \rightarrow 2Fe_2O_3\). This process involves adjusting coefficients before the chemical formulas to make sure that the number of atoms of each element is the same on both sides of the equation.

Oxidation states, also known as oxidation numbers, help us keep track of how many electrons are gained or lost by an atom in a chemical reaction. They indicate the degree of oxidation (loss of electrons) or reduction (gain of electrons) an atom undergoes.
Iron, for instance, can exist in multiple oxidation states such as +2 (ferrous) and +3 (ferric). In the compound \(FeO\), iron has an oxidation state of +2, meaning it has lost two electrons. In \(Fe_2O_3\), iron is in a +3 oxidation state, indicating the loss of three electrons.
The process of moving from \(FeO\) to \(Fe_2O_3\) involves the oxidation of iron, meaning Fe is transitioning from a +2 to +3 oxidation state. This is a key aspect of understanding the changes during this reaction.

Iron oxides are compounds composed of iron and oxygen atoms. There are several different types of iron oxides, each with distinct chemical compositions and properties.
The most common iron oxides include ferric oxide \(Fe_2O_3\), ferrous oxide \(FeO\), and magnetite \(Fe_3O_4\).

• \(FeO\) is known as iron(II) oxide or ferrous oxide. It is less stable and easily reacts with oxygen to form other oxides.
• \(Fe_2O_3\) is iron(III) oxide or ferric oxide. It is more stable and commonly found in nature as hematite. This is what forms when \(FeO\) reacts with more oxygen.
• \(Fe_3O_4\), or magnetite, is a mixed oxide with iron in both +2 and +3 oxidation states, containing a mix of the properties of \(FeO\) and \(Fe_2O_3\).

In the provided exercise, the transformation of \(FeO\) to \(Fe_2O_3\) involves the combination of iron(II) oxide with oxygen to form iron(III) oxide. Through the balancing process, we ensured that both iron and oxygen atoms are conserved, ultimately yielding a balanced reaction equation.