Which of the following is the molar mass of BF_3?

• A. 48.81 g/mol
• B. 67.81 g/mol
• C. 20.81 g/mol
• D. 86.81 g/mol

Answer: (B)

Verified step by step guidance

1. Identify the elements present in the compound BF_3, which are boron (B) and fluorine (F).
2. Determine the number of atoms of each element in one molecule of BF_3: 1 atom of boron and 3 atoms of fluorine.
3. Find the atomic masses of each element from the periodic table: boron (approximately 10.81 g/mol) and fluorine (approximately 18.998 g/mol).
4. Calculate the total mass contributed by each element by multiplying the atomic mass by the number of atoms: for boron, multiply 10.81 g/mol by 1; for fluorine, multiply 18.998 g/mol by 3.
5. Add the total masses of boron and fluorine together to get the molar mass of BF_3 using the formula: \(\text{Molar mass of BF}_3 = (1 \times 10.81) + (3 \times 18.998)\) g/mol.