In which of the following reactions, oxygen is an oxidant?

Options

A. `2F_(2)+O_(2)to2F_(2)O`
B. `C+O_(2)toCO_(2)`
C. `2C+O_(2)to2CO`
D. `2N_(2)+O_(2)to2N_(2)O`

Answer

To determine in which of the given reactions oxygen acts as an oxidant, we need to analyze the oxidation states of the elements involved in each reaction. An oxidant (or oxidizing agent) is a substance that causes another substance to be oxidized, which means it itself is reduced (gains electrons and its oxidation state decreases).

### Step-by-Step Solution:

1. **Understand the Definition of an Oxidant**:
- An oxidant is a substance that gains electrons in a chemical reaction, leading to a decrease in its oxidation state while causing another substance to be oxidized.

2. **Analyze Each Reaction**:
- We will check the oxidation states of the elements in each reaction to see if oxygen is acting as an oxidant.

3. **Reaction A: 2F2 + O2 → 2F2O**:
- Oxidation states:
- F2: F = 0
- O2: O = 0
- In F2O: F = -1, O = +2
- Change in oxidation states:
- F changes from 0 to -1 (reduction).
- O changes from 0 to +2 (oxidation).
- Conclusion: Oxygen is oxidized, therefore it is a reducing agent, not an oxidant.

4. **Reaction B: C + O2 → CO2**:
- Oxidation states:
- C: C = 0
- O2: O = 0
- In CO2: C = +4, O = -2
- Change in oxidation states:
- C changes from 0 to +4 (oxidation).
- O changes from 0 to -2 (reduction).
- Conclusion: Oxygen is reduced, therefore it is an oxidant.

5. **Reaction C: 2C + O2 → 2CO**:
- Oxidation states:
- C: C = 0
- O2: O = 0
- In CO: C = +2, O = -2
- Change in oxidation states:
- C changes from 0 to +2 (oxidation).
- O changes from 0 to -2 (reduction).
- Conclusion: Oxygen is reduced, therefore it is an oxidant.

6. **Reaction D: 2N2 + O2 → 2N2O**:
- Oxidation states:
- N2: N = 0
- O2: O = 0
- In N2O: N = +1, O = -2
- Change in oxidation states:
- N changes from 0 to +1 (oxidation).
- O changes from 0 to -2 (reduction).
- Conclusion: Oxygen is reduced, therefore it is an oxidant.

7. **Final Conclusion**:
- In reactions B, C, and D, oxygen acts as an oxidant because it causes the reduction of other elements while itself being reduced.

### Final Answer:
Oxygen is an oxidant in reactions B, C, and D.

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