Question

oxygen is acting as an oxidizing agent in all of the following reactions except
a.
2 c(s) + o₂(g) → 2 co(g)
b.
s(s) + o₂(g) → so₂(g)
c.
2 f₂(g) + o₂(g) → 2 of₂(g)
d.
2 na(s) + o₂(g) → na₂o₂(s)
e.
2 mg(s) + o₂(g) → 2 mgo(s)

Explanation:

To determine when oxygen is not an oxidizing agent, we analyze the oxidation state of oxygen in each reaction:

• In an oxidizing agent, the element (oxygen here) gains electrons, so its oxidation state decreases.
• Option A: In \(O_2\) (oxidation state = 0), in \(CO\), O has oxidation state -2. So O gains electrons (oxidation state decreases from 0 to -2), so \(O_2\) is an oxidizing agent.
• Option B: In \(O_2\) (0), in \(SO_2\), O has -2. O gains electrons, so \(O_2\) is an oxidizing agent.
• Option C: In \(O_2\) (0), in \(OF_2\), O has +2 (since F is -1, and \(2\times(-1)+x = 0\) gives \(x = +2\)). O loses electrons (oxidation state increases from 0 to +2), so \(O_2\) is a reducing agent here (not an oxidizing agent).
• Option D: In \(O_2\) (0), in \(Na_2O_2\), O has -1. O gains electrons (oxidation state decreases from 0 to -1), so \(O_2\) is an oxidizing agent.
• Option E: In \(O_2\) (0), in \(MgO\), O has -2. O gains electrons (oxidation state decreases from 0 to -2), so \(O_2\) is an oxidizing agent.

Answer:

C. \(2 F_2(g) + O_2(g)
ightarrow 2 OF_2(g)\)