Question

In all oxides, peroxides and superoxides, the oxidation state of alkali metals is (a) \(+1\) and \(-1\) (b) \(+1\) and \(+2\) (c) \(+1\) only (d) \(+1,-1\) and \(+2\)

Short answer

The oxidation state of alkali metals in oxides, peroxides, and superoxides is +1 only, so the correct option is (c) +1 only.

Step-by-step solution

Understand the Composition of Oxides, Peroxides and Superoxides

Oxides are compounds that contain the oxygen anion (O^2-) combined with another element. Peroxides contain the peroxide anion (O2^2-) and superoxides contain the superoxide anion (O2^-).

Determine the Oxidation State of Alkali Metals in Oxides

Alkali metals (Group 1 elements) in oxides have a stable +1 oxidation state because they donate one electron to form a cation (M^+), which then combines with oxygen which has a -2 charge, to form the compound (M2O).

Analyze the Oxidation State in Peroxides and Superoxides

In peroxides, alkali metals also exhibit a +1 oxidation state interacting with the peroxide anion (O2^2-), resulting in compounds like M2O2. In superoxides, alkali metals maintain the +1 oxidation state despite oxygen being in a different form, resulting in compounds like MO2.

Conclude the Oxidation State

Considering the behavior of alkali metals in these compounds, it can be concluded that the oxidation state of alkali metals in oxides, peroxides, and superoxides is always +1.

Key concepts

Oxides Chemistry

Oxides form a vast and vital part of chemistry, especially when discussing the behavior of alkali metals. An oxide is any chemical compound that includes at least one oxygen atom and one other element, arranged in various ways and exhibiting diverse properties. The most common type of oxide is where the oxygen atom is bonded to another element with a -2 oxidation state. Alkali metals, which are members of Group 1 on the periodic table, react with oxygen to form simple oxides. Considering their active nature, these metals readily lose their single outer electron to achieve a stable electron configuration, corresponding to a +1 oxidation state.

Alpha ChenIn their oxide form, alkali metals combine with oxygen to produce a binary compound with a general formula of M2O, where 'M' represents the alkali metal. These compounds are ionic in nature, characterized by a high melting point and the ability to conduct electricity when melted or dissolved in water. Common examples include sodium oxide (Na2O) and potassium oxide (K2O).

Peroxides

Peroxides are a class of compounds where the oxygen-oxygen pairing is prominent, with the two oxygen atoms bonded together and each carrying a -1 oxidation state. This unique arrangement results in the peroxide anion (O2^2-). When alkali metals form peroxides, they do so by donating one electron, similar to how they form oxides, keeping their oxidation state at +1.

In the case of peroxides, the general structure they form with alkali metals is M2O2. It's important to note that peroxides can act as a source of hydrogen peroxide (H2O2) upon reaction with dilute acids. They also serve as important bleaching agents and are prevalent in various industries such as textile and paper manufacturing. Additionally, hydrogen peroxide itself is an example of a pure peroxide compound, frequently used as a disinfectant and bleaching agent.

Superoxides

Superoxides represent another oxide category where the oxygen species involved is superoxide, an anion with a chemical formula of O2^- and each oxygen atom having an apparent oxidation state of -1/2. However, the overall charge of superoxide is -1 because the anion comprises two oxygen atoms.

When bound to an alkali metal, the metal retains its +1 oxidation state, but the formula adopts a slightly different structure, typically MO2, indicating a more complex interaction between the metal and the oxygen species. Superoxides are powerful oxidizing agents and are known to be unstable due to the presence of an unpaired electron on the superoxide ion, which imparts radical-like properties. These compounds have significant biological implications, acting as byproducts of metabolic processes in cells that can contribute to oxidative stress. Potassium superoxide (KO2) is often used in life support systems to both provide oxygen and remove carbon dioxide from breathing air.