What is the formula weight of barium phosphate, Ba3(PO4)2? 601.9 amu
The Correct Answer and Explanation is:
Correct Answer: 601.9 amu
Explanation:
The formula weight (also called the molecular weight or molar mass) of a compound is the sum of the atomic weights of all atoms in its chemical formula. In this case, we are asked to find the formula weight of barium phosphate, which has the chemical formula Ba₃(PO₄)₂.
To calculate the formula weight, we need to consider how many atoms of each element are present and multiply by their respective atomic masses. Let’s break this down:
Step 1: Determine the number of atoms:
- Barium (Ba): 3 atoms
- Phosphorus (P): 2 atoms (since there are 2 phosphate groups)
- Oxygen (O): 8 atoms (each phosphate group has 4 oxygen atoms × 2)
Step 2: Use the atomic weights from the periodic table:
- Barium (Ba): 137.33 amu
- Phosphorus (P): 30.97 amu
- Oxygen (O): 16.00 amu
Step 3: Multiply the atomic weights by the number of atoms:
- Barium: 3 × 137.33 = 411.99 amu
- Phosphorus: 2 × 30.97 = 61.94 amu
- Oxygen: 8 × 16.00 = 128.00 amu
Step 4: Add all the contributions together:
- Total formula weight = 411.99 + 61.94 + 128.00 = 601.93 amu
Rounded to one decimal place, the formula weight of Ba₃(PO₄)₂ is 601.9 amu.
This value represents the mass of one formula unit of barium phosphate in atomic mass units (amu), which is essential for stoichiometric calculations in chemistry such as determining moles, mass relationships, and reaction yields.
