what is the empirical formula for a compound if a sample contains 3.72 g of p and 21.28 g of cl?\no pcl5\no…

Answer:

A. $\text{PCl}_5$

Explanation:

Step1: Calculate moles of P

Molar mass of P is 30.97 g/mol. Moles of P = $\frac{3.72\ g}{30.97\ g/mol}\approx0.12\ mol$

Step2: Calculate moles of Cl

Molar mass of Cl is 35.45 g/mol. Moles of Cl = $\frac{21.28\ g}{35.45\ g/mol}\approx0.6\ mol$

Step3: Find mole - ratio

Divide moles of each element by moles of P (smaller value). Mole - ratio of Cl to P = $\frac{0.6\ mol}{0.12\ mol}= 5$. So empirical formula is $\text{PCl}_5$.