How many moles of phosphine are produced when one of the calcium phosphides reacts with water?

Explanation

To determine how many moles of phosphine (PH₃) are produced when one mole of calcium phosphide (Ca₃P₂) reacts with water, we need to follow these steps:

### Step 1: Write the balanced chemical equation
The reaction between calcium phosphide and water can be represented as follows:

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

### Step 2: Balance the chemical equation
To balance the equation, we need to ensure that the number of atoms of each element is the same on both sides of the equation.

1. **Calcium (Ca)**: There are 3 calcium atoms in calcium phosphide, so we need 3 calcium hydroxide (Ca(OH)₂) on the product side:
\[ \text{Ca}_3\text{P}_2 + \text{H}_2\text{O} \rightarrow 3\text{Ca(OH)}_2 + \text{PH}_3 \]

2. **Phosphorus (P)**: There are 2 phosphorus atoms in calcium phosphide, so we need 2 phosphine (PH₃) on the product side:
\[ \text{Ca}_3\text{P}_2 + \text{H}_2\text{O} \rightarrow 3\text{Ca(OH)}_2 + 2\text{PH}_3 \]

3. **Hydrogen (H)**: Now we count the hydrogen atoms. On the right side, we have:
- From 3 Ca(OH)₂: \( 3 \times 2 = 6 \) hydrogen atoms
- From 2 PH₃: \( 2 \times 3 = 6 \) hydrogen atoms
- Total = 6 + 6 = 12 hydrogen atoms.

4. **Oxygen (O)**: We have 6 oxygen atoms from 3 Ca(OH)₂, and we need 6 water molecules to balance the equation:
\[ \text{Ca}_3\text{P}_2 + 6\text{H}_2\text{O} \rightarrow 3\text{Ca(OH)}_2 + 2\text{PH}_3 \]

### Step 3: Determine the moles of phosphine produced
From the balanced equation, we can see that 1 mole of calcium phosphide (Ca₃P₂) produces 2 moles of phosphine (PH₃).

### Conclusion
Thus, when 1 mole of calcium phosphide reacts with water, it produces **2 moles of phosphine**.