Question

Which one of the following is not a true peroxide? (d) \(\overline{\mathrm{H}_{2} \mathrm{SO}_{4}}\) (a) \(\overline{\mathrm{PbO}_{2}}\) (b) \(\mathrm{BaO}_{2}\) (c) \(\mathrm{Na}_{2} \mathrm{O}_{2}\)

Short answer

(d) Sulfuric acid ( \(\overline{\mathrm{H}_{2} \mathrm{SO}_{4}}\) ) is not a true peroxide.

Step-by-step solution

Understanding the Definition of a Peroxide

A peroxide is a compound that contains an oxygen-oxygen single bond, represented as (-O-O-) . In peroxides, the oxidation state of each oxygen atom is (-1) .

Analyzing Each Compound

For each option, check if it contains the (-O-O-) bond:- (a) \(\overline{\mathrm{PbO}_{2}}\) : Lead(IV) oxide does not contain an (-O-O-) bond; it is not a true peroxide.- (b) \(\mathrm{BaO}_{2}\) : Barium peroxide, which contains the (-O-O-) bond; it is a true peroxide.- (c) \(\mathrm{Na}_{2} \mathrm{O}_{2}\) : Sodium peroxide, which contains the (-O-O-) bond; it is a true peroxide.- (d) \(\overline{\mathrm{H}_{2} \mathrm{SO}_{4}}\) : Sulfuric acid does not contain an (-O-O-) bond; it is not a true peroxide.

Identifying the Compound That Is Not a True Peroxide

From the analysis, compounds (b) \(\mathrm{BaO}_{2}\) and (c) \(\mathrm{Na}_{2} \mathrm{O}_{2}\) contain (-O-O-) bonds, making them true peroxides. Compound (a) \(\overline{\mathrm{PbO}_{2}}\) , although named 'peroxide', does not have the typical dioxygen linkage and is not classified as a true peroxide. Compound (d) \(\overline{\mathrm{H}_{2} \mathrm{SO}_{4}}\) is sulfuric acid and does not contain the (-O-O-) bond.

Key concepts

Oxygen-Oxygen Bond

The oxygen-oxygen bond, also known as the peroxo bond, is a defining feature in peroxides. It consists of a single bond that directly links two oxygen atoms. In chemical notation, this bond is often represented by the structural unit (-O-O-). The presence of this bond is a key indicator that a compound is a peroxide.
Common examples include hydrogen peroxide (\( H_2O_2 \)), barium peroxide (\( BaO_2 \)), and sodium peroxide (\( Na_2O_2 \)). It is important to recognize this bond, as it signifies that each oxygen in the bond has an oxidation state of -1. This distinctive bond sets peroxides apart from other oxygen-containing compounds.

Oxidation State of Oxygen

In most compounds, oxygen typically exhibits an oxidation state of -2 due to its high electronegativity. However, in peroxides, the situation is different. Here, each oxygen atom in the oxygen-oxygen bond has an oxidation state of -1. This unique characteristic helps identify true peroxide compounds.
Understanding the oxidation state is crucial when analyzing chemical formulas, as it can reveal the nature of chemical bonds and compound classifications. The alteration in the oxidation state is a result of the unique bonding between the two oxygen atoms, emphasizing the special nature of peroxides in chemistry.

Barium Peroxide

Barium peroxide (\( BaO_2 \)) is a prototypical example of a peroxide compound. It is recognized by the presence of the oxygen-oxygen bond, which classifies it as a true peroxide. As a solid, barium peroxide appears as a white or grayish powder. It serves various industrial purposes, such as in the production of hydrogen peroxide.
Chemically, barium peroxide decomposes upon heating to produce barium oxide (\( BaO \)) and oxygen gas (\( O_2 \)). This decomposition underscores the useful oxidation properties of peroxides, making them valuable in applications that require oxygen release.

Sodium Peroxide

Sodium peroxide (\( Na_2O_2 \)) is another true peroxide characterized by the presence of the (-O-O-) bond. In sodium peroxide, each oxygen maintains an oxidation state of -1, consistent with peroxide classification. When it interacts with water, sodium peroxide reacts to form sodium hydroxide (\( NaOH \)) and oxygen gas (\( O_2 \)).
Its ability to release oxygen upon decomposition makes it useful in various settings, such as chemical industry and emergency oxygen supply systems. The properties of sodium peroxide highlight the significant reactivity typical of peroxides, particularly their role in oxidizing reactions.