Nature of Oxides

Q. Suboxides are a class of oxides wherein the electropositive element is in excess relative to the “normal” oxides - True or False?

1. True
2. False

Q.

The formation of the oxide ion, $O_{\left(g\right)}^{2-}$ from oxygen atom requires first an exothermic and then an endothermic step as shown below:
$O_{\left(g\right)}+e^{-}\to O_{\left(g\right)}^{-};{\Delta }_f{H}^{\circ }=-141kJmo{l}^{-1}{O}_{\left(g\right)}^{-}+e^{-}\to O_{\left(g\right)}^{2-};{\Delta }_f{H}^{\circ }=+780kJmo{l}^{-1}$
Thus, process of formation of $O^{2-}$ in gas phase is unfavourable even though $O^{2-}$ is isoelectronic with neon. It is due to the fact that,

1. $O^{-}$ ion has comparatively smaller size than oxygen atom.

2. oxygen is more electronegative

3. addition of electron in oxygen results in larger size of the ion.

4. electron repulsion outweighs the stability gained by achieving noble gas configuration.

Q.

The formation of the oxide ion, $O_{\left(g\right)}^{2-}$ from oxygen atom requires first an exothermic and then an endothermic step as shown below:
$O_{\left(g\right)}+e^{-}\to O_{\left(g\right)}^{-};{\Delta }_f{H}^{\circ }=-141kJmo{l}^{-1}{O}_{\left(g\right)}^{-}+e^{-}\to O_{\left(g\right)}^{2-};{\Delta }_f{H}^{\circ }=+780kJmo{l}^{-1}$
Thus, process of formation of $O^{2-}$ in gas phase is unfavourable even though $O^{2-}$ is isoelectronic with neon. It is due to the fact that,

1. $O^{-}$ ion has comparatively smaller size than oxygen atom.

2. oxygen is more electronegative

3. addition of electron in oxygen results in larger size of the ion.

4. electron repulsion outweighs the stability gained by achieving noble gas configuration.

Q. Which of the following is true for Super oxides?

1. Chemical formula of anion is $O_2^{-}$
2. They are also called hyperoxide
3. Both (A) and (B)
4. None of these