Question

Correct formula of sodium peroxide is :

• A. NaO
• B. \(\text{Na}_2\text{O}\)
• C. \(\text{NaO}_2\)
• D. \(\text{Na}_2\text{O}_2\)

Hint:

Sodium (Na) forms ions with +1 charge (\(Na^+\)). Oxygen can form different ions:
Oxide: O\(^{2-}\) \(\rightarrow\) Sodium Oxide is \(\text{Na}_2\text{O}\)
Peroxide: O\(_2^{2-}\) \(\rightarrow\) Sodium Peroxide is \(\text{Na}_2\text{O}_2\) (Need two Na\(^+\) to balance O\(_2^{2-}\))
Superoxide: O\(_2^{-}\) \(\rightarrow\) Sodium Superoxide is \(\text{NaO}_2\) (Need one Na\(^+\) to balance O\(_2^{-}\)) The question asks for Sodium {Peroxide}.

Answer 1

The Correct Option is D

Concept: Sodium forms different types of compounds with oxygen: oxides, peroxides, and superoxides, depending on the reaction conditions and the nature of the oxygen species involved.
Oxide ion: O\(^{2-}\)
Peroxide ion: O\(_2^{2-}\) (contains an O-O single bond)
Superoxide ion: O\(_2^{-}\) (contains an O-O bond with bond order 1.5) Sodium (Na) is an alkali metal and typically forms ions with a +1 charge (Na\(^+\)). Step 1: Determine the charges of the ions to form a neutral compound
Sodium ion: Na\(^+\) (charge +1)
Peroxide ion: O\(_2^{2-}\) (charge -2) Step 2: Combine the ions to form a neutral compound (Sodium Peroxide) To balance the charges for sodium peroxide: We need two Na\(^+\) ions to balance the -2 charge of one O\(_2^{2-}\) ion. Total positive charge = \(2 \times (+1) = +2\). Total negative charge = \(1 \times (-2) = -2\). The overall charge is \(+2 + (-2) = 0\). So, the formula for sodium peroxide is \(\text{Na}_2\text{O}_2\). Step 3: Analyzing the options
(1) NaO: If oxygen has a -2 charge (oxide), then Na would need a +2 charge, which is not typical for sodium. If it's Na\(^+\) and O\(^-\), this would be a radical species, not standard sodium oxide.
(2) \(\text{Na}_2\text{O}\): This is Sodium Oxide. Here, two Na\(^+\) ions combine with one O\(^{2-}\) (oxide) ion.
(3) \(\text{NaO}_2\): This is Sodium Superoxide. Here, one Na\(^+\) ion combines with one O\(_2^{-}\) (superoxide) ion.
(4) \(\text{Na}_2\text{O}_2\): This is Sodium Peroxide. Here, two Na\(^+\) ions combine with one O\(_2^{2-}\) (peroxide) ion. Correct. The handwritten "NaO\(_2\)" near the question might be a misinterpretation or a note about superoxide, but the question asks for peroxide. The formula for sodium peroxide is \(\text{Na}_2\text{O}_2\).