Final answer:
To find the number of moles of POCl₃ in 10.0 grams of POCl₃, you first calculate the molar mass of POCl₃ and then divide the given mass by that molar mass. The calculation results in approximately 0.0652 moles, and the closest answer choice is A. 6.51 × 10⁻² mol.
Step-by-step explanation:
To calculate the number of moles of POCl₃ in 10.0 grams, you should first determine the molar mass of POCl₃. Phosphorus (P) has an atomic mass of approximately 30.97, oxygen (O) has an atomic mass of 16.00, and chlorine (Cl) has an atomic mass of approximately 35.45.
Since POCl₃ includes one atom of phosphorus, one atom of oxygen, and three atoms of chlorine, the molar mass is calculated by adding these atomic masses together: 30.97 (P) + 16.00 (O) + 3 × 35.45 (Cl) = 153.32 grams per mole.
Then, to find the moles of POCl₃, divide the given mass by the molar mass:
10.0 grams POCl₃ × (1 mol POCl₃ / 153.32 grams POCl₃) = 0.0652 moles of POCl₃
The closest answer choice in the selection provided is A. 6.51 × 10⁻² mol, which rounds to approximately 0.0651 moles.