The p-p bond energy is 'x' KJ/mole. Then the energy needed for the dissociation of 124 g of white phosphorous is 

Options

A. x KJ
B. 4x KJ
C. 6x KJ
D. 8x KJ

Answer

To solve the problem of calculating the energy needed for the dissociation of 124 g of white phosphorus (P4), we can follow these steps:

### Step 1: Identify the molecular formula and structure of white phosphorus
White phosphorus exists as P4, which means each molecule consists of 4 phosphorus atoms arranged in a tetrahedral structure.

**Hint:** Remember that the molecular formula indicates how many atoms are present in one molecule.

### Step 2: Determine the number of P-P bonds in P4
In the P4 molecule, there are 6 P-P bonds. This can be visualized by drawing the tetrahedral structure and counting the bonds between the phosphorus atoms.

**Hint:** Visualizing the molecular structure can help in counting the number of bonds.

### Step 3: Understand the bond energy given in the problem
The problem states that the P-P bond energy is 'x' kJ/mole. This means that to break one mole of P-P bonds, 'x' kJ of energy is required.

**Hint:** Bond energy is the energy required to break one mole of a specific type of bond.

### Step 4: Calculate the energy required to dissociate one mole of P4
Since there are 6 P-P bonds in one mole of P4, the energy required to dissociate all the P-P bonds in one mole of P4 is:
\[ \text{Energy for 1 mole of P4} = 6 \times x \text{ kJ} \]

**Hint:** Multiply the number of bonds by the energy required to break one bond.

### Step 5: Relate the mass of phosphorus to moles
The molecular weight of phosphorus (P) is 31 g/mol. Therefore, the molecular weight of P4 is:
\[ 4 \times 31 \text{ g/mol} = 124 \text{ g/mol} \]
This means that 124 g of white phosphorus corresponds to 1 mole of P4.

**Hint:** Use the molar mass to convert grams to moles.

### Step 6: Conclude the total energy needed
Since 124 g of white phosphorus corresponds to 1 mole of P4, the energy needed to dissociate 124 g of white phosphorus is the same as the energy needed to dissociate 1 mole of P4:
\[ \text{Energy needed} = 6x \text{ kJ} \]

### Final Answer:
The energy needed for the dissociation of 124 g of white phosphorus is **6x kJ**.

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