In which of the following compounds, oxygen exhibits an oxidation state of \(+2\) ? (a) \(\mathrm{H}_{2} \mathrm{O}_{2}\) (b) \(\mathrm{OF}_{2}\) (c) \(\mathrm{H}_{2} \mathrm{O}\) (d) \(\mathrm{H}_{2} \mathrm{SO}_{4}\)

Chemical compounds are substances formed by the chemical combination of two or more elements in definite proportions and held together by chemical bonds. Each element within a compound is present in a specific ratio, giving the compound its unique properties. For instance, water, with its molecular formula of H₂O, consists of two hydrogen atoms bonded to one oxygen atom. The properties of compounds are determined by the nature of the elements involved and how they are bonded together.

Identifying each element's oxidation state in a compound is crucial to understanding its chemical behavior. For example, in hydrogen peroxide (H₂O₂), oxygen has a different oxidation state than in water because of the arrangement and type of bonds between the atoms. As we explore the various compounds such as H₂O₂, OF₂, H₂O, and H₂SO₄, we notice that oxygen's oxidation state varies, providing insight into the compound's chemical reactivity and how it might interact with other substances.

The oxidation state, often known as the oxidation number, is a concept used in chemistry to help keep track of electron transfers in oxidation-reduction (redox) reactions. Oxidation states are assigned to atoms based on a set of rules. Typically, the oxidation state of oxygen in compounds is -2, but there are exceptions that we need to be aware of:

• In peroxides, such as H₂O₂, each oxygen atom has an oxidation state of -1 due to the single bond between the two oxygen atoms.
• With more electronegative elements like fluorine, oxygen can have a positive oxidation state because fluorine will attract the bonding electrons more strongly, as seen in compounds like OF₂.

To determine the oxidation state of an element in a compound, one must consider these rules alongside the total charge of the molecule. By applying these principles, as done in the steps of our solution, we can deduce that in the compound OF₂, oxygen has a rare positive oxidation state of +2 to balance the more electronegative fluorines.

Electronegativity is a measure of an atom's ability to attract and hold onto electrons within a chemical bond. It is a fundamental property that affects how atoms interact with each other in a molecule. The Pauling scale is the most commonly used system to quantify electronegativity, with higher values indicating greater electronegativity.

In the context of determining oxidation states, electronegativity plays a pivotal role. Typically, the more electronegative element in a bond acquires a negative oxidation state due to its ability to attract shared electrons. For example, fluorine is the most electronegative element and will almost always have an oxidation state of -1 in its compounds, overpowering oxygen's usual oxidation state of -2.

In the case of OF₂, because fluorine (F) is more electronegative than oxygen (O), it retains a -1 oxidation state, while oxygen (O), being less electronegative in this scenario, is assigned a +2 oxidation state. Understanding how electronegativity determines the distribution of electrons in a compound can help predict the compound's chemical and physical properties.