Final answer:
The molecular weight of PCl3 is the sum of the atomic weights of one phosphorus atom and three chlorine atoms, resulting in a molecular weight of 137.32 amu.
Step-by-step explanation:
The molecular weight of PCl3 (Phosphorus trichloride) is calculated by summing the average atomic masses of phosphorus (P) and chlorine (Cl) atoms in the molecule. To calculate this, we use the formula:
- P: 1 x 30.97 = 30.97 amu
- Cl: 3 x 35.45 = 106.35 amu (using the average atomic mass of chlorine)
By adding the subtotals of P and Cl, we get:
30.97 amu (for P) + 106.35 amu (for Cl) = 137.32 amu
Therefore, the molecular weight of PCl3 is 137.32 amu. This is the total sum of the individual atoms' average atomic masses within a single molecule of phosphorus trichloride.