Red P+Alkali `toNa_(4)P_(2)O_(6)+P_(2)H_(4)`

Options

A. For disproportionation reaction.
B. For comproportionation reaction.
C. For either intermolecular redox reaction or displacement reaction
D. For either thermal combination redox reaction or thermal decomposition redox reaction.

Answer

To solve the question regarding the reaction of red phosphorus (P) with an alkali to produce sodium metaphosphate (Na4P2O6) and phosphine (P2H4), we need to analyze the oxidation states of phosphorus in the reactants and products. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Reactants and Products
The reactants are red phosphorus (P) and an alkali (we can assume sodium hydroxide, NaOH). The products are sodium metaphosphate (Na4P2O6) and phosphine (P2H4).

### Step 2: Determine the Oxidation State of Phosphorus in Reactants
In red phosphorus (P4), the oxidation state of phosphorus is 0 because it is in its elemental form.

### Step 3: Determine the Oxidation State of Phosphorus in Products
1. **For Na4P2O6:**
- Sodium (Na) has an oxidation state of +1.
- Oxygen (O) has an oxidation state of -2.
- Let the oxidation state of phosphorus be \( x \).
- The equation for the oxidation states will be:
\[ 4(+1) + 2x + 6(-2) = 0 \]
Simplifying this gives:
\[ 4 + 2x - 12 = 0 \implies 2x - 8 = 0 \implies 2x = 8 \implies x = +4 \]
- Therefore, the oxidation state of phosphorus in Na4P2O6 is +4.

2. **For P2H4:**
- Hydrogen (H) has an oxidation state of +1.
- Let the oxidation state of phosphorus be \( y \).
- The equation for the oxidation states will be:
\[ 2y + 4(+1) = 0 \]
Simplifying this gives:
\[ 2y + 4 = 0 \implies 2y = -4 \implies y = -2 \]
- Therefore, the oxidation state of phosphorus in P2H4 is -2.

### Step 4: Analyze the Changes in Oxidation State
- In the reaction, phosphorus changes from an oxidation state of 0 in P4 to +4 in Na4P2O6 (oxidation) and to -2 in P2H4 (reduction).
- This indicates that the same element (phosphorus) is undergoing both oxidation and reduction.

### Step 5: Conclusion
Since phosphorus is both oxidized and reduced in the reaction, this is classified as a **disproportionation reaction**.

### Final Answer
The reaction is a **disproportionation reaction**.

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