In the reaction `PCl_(3) + Cl_(2) to PCl_5`, which of the following is correct?

Options

A. `PCl_(3)` is acting as a reductant.
B. `Cl_(2)` is acting as a reductant.
C. Both `PCl_(3) and Cl_(2)` are acting as reductants
D. Both `PCl_(3) and Cl_(2)` are acting as oxidants

Answer

To solve the question regarding the reaction \( PCl_3 + Cl_2 \to PCl_5 \) and determine which statements about the reactants and products are correct, we will analyze the oxidation states of the elements involved in the reaction.

### Step-by-Step Solution:

1. **Identify the Reactants and Products**:
- The reactants are \( PCl_3 \) (phosphorus trichloride) and \( Cl_2 \) (chlorine gas).
- The product is \( PCl_5 \) (phosphorus pentachloride).

2. **Determine the Oxidation States**:
- For \( PCl_3 \):
- Chlorine (Cl) usually has an oxidation state of -1.
- Let the oxidation state of phosphorus (P) be \( x \).
- The equation for \( PCl_3 \) is:
\[ x + 3(-1) = 0 \implies x - 3 = 0 \implies x = +3 \]
- Thus, the oxidation state of phosphorus in \( PCl_3 \) is +3.

- For \( PCl_5 \):
- Again, let the oxidation state of phosphorus be \( x \).
- The equation for \( PCl_5 \) is:
\[ x + 5(-1) = 0 \implies x - 5 = 0 \implies x = +5 \]
- Thus, the oxidation state of phosphorus in \( PCl_5 \) is +5.

- For \( Cl_2 \):
- The oxidation state of chlorine in \( Cl_2 \) is 0 (as it is in its elemental form).

3. **Analyze the Changes in Oxidation States**:
- Phosphorus changes from +3 in \( PCl_3 \) to +5 in \( PCl_5 \). This indicates that phosphorus is being oxidized (losing electrons).
- Chlorine changes from 0 in \( Cl_2 \) to -1 in \( PCl_5 \). This indicates that chlorine is being reduced (gaining electrons).

4. **Identify the Reducing and Oxidizing Agents**:
- Since phosphorus is oxidized, \( PCl_3 \) acts as a reducing agent (it donates electrons).
- Since chlorine is reduced, \( Cl_2 \) acts as an oxidizing agent (it accepts electrons).

5. **Conclusion**:
- The correct statement is that \( PCl_3 \) is acting as a reductant (reducing agent).
- Therefore, the answer to the question is: **Option 1 is correct: \( PCl_3 \) is acting as a reductant.**