Final answer:
The molecular formula of a compound with a molar mass of 381 g/mol and an empirical formula of PS2 is P4S8. This is determined by calculating the molar mass of the empirical formula PS2 and comparing it to the compound's molar mass to find they differ by a factor of 4.
Step-by-step explanation:
To determine the molecular formula of a compound with a molar mass of approximately 381 g/mol and an empirical formula of PS2, you must first calculate the molar mass of the empirical formula and then compare it to the molar mass of the compound.
- First, calculate the molar mass of PS2:
- Phosphorus (P) has a molar mass of about 30.97 g/mol.
- Sulfur (S) has a molar mass of about 32.06 g/mol.
- The molar mass of PS2 = 30.97 g/mol + 2(32.06 g/mol) = 95.09 g/mol.
- Next, divide the molar mass of the compound by the molar mass of the empirical formula:
- 381 g/mol ÷ 95.09 g/mol ≈ 4.
- This indicates that the molecular formula contains 4 times the number of atoms in the empirical formula.
- Therefore, the molecular formula is P4S8, which is option (a) P4S8.