One mole of calcium phosphide on reaction with excess of water gives

Options

A. one mole of phosphine
B. two moles of phosphoric acid
C. two moles of phosphine
D. one mole of phosphorus pentoxide.

Answer

To solve the problem of what one mole of calcium phosphide (Ca3P2) produces when it reacts with excess water, we can follow these steps:

### Step 1: Write the chemical equation for the reaction
Calcium phosphide reacts with water to form calcium hydroxide and phosphine. The balanced chemical equation for the reaction is:

\[ \text{Ca}_3\text{P}_2 + 6 \text{H}_2\text{O} \rightarrow 3 \text{Ca(OH)}_2 + 2 \text{PH}_3 \]

### Step 2: Analyze the stoichiometry of the reaction
From the balanced equation, we can see the following stoichiometric relationships:
- 1 mole of calcium phosphide (Ca3P2) produces 3 moles of calcium hydroxide (Ca(OH)2).
- 1 mole of calcium phosphide (Ca3P2) produces 2 moles of phosphine (PH3).

### Step 3: Determine the products from one mole of calcium phosphide
Since we are starting with 1 mole of calcium phosphide:
- It will produce 3 moles of calcium hydroxide.
- It will produce 2 moles of phosphine.

### Step 4: Identify the correct answer from the options
The question asks what is produced when one mole of calcium phosphide reacts with excess water. From our analysis, we found that 2 moles of phosphine are produced. Therefore, the correct answer is:

**Option 3: 2 moles of phosphine (PH3)**.

### Summary of the Solution
1. Write the balanced chemical equation:
\[ \text{Ca}_3\text{P}_2 + 6 \text{H}_2\text{O} \rightarrow 3 \text{Ca(OH)}_2 + 2 \text{PH}_3 \]
2. From the equation, determine that 1 mole of Ca3P2 produces 2 moles of PH3.
3. Conclude that the answer is Option 3: 2 moles of phosphine.