# How do you determine the molar mass of BF_3?

Jul 17, 2016

$\textcolor{h o t \pi n k}{\text{67.81 g/mol}}$

#### Explanation:

$\textcolor{p u r p \le}{\text{We will use the formula below to answer the question:}}$

atomic weight of element $\times$number of atoms given by subscript $=$ molar mass

First, you want to have a periodic table available so you can determine the atomic weight of B and F:

• B has an atomic weight of 10.811 g/mol
• F has an atomic wight of 19.00 g/mol

From the chemical formula, we have 1 boron atom, so the atomic mass would just be 10.811 g/mol

Next, you have 3 fluorine atoms, so you would multiply the atomic mass of F by 3 to obtain an atomic weight of 57.00 g/mol

Now you want to add the mass of each atom together to obtain the molar mass of the entire compound:

$\textcolor{red}{\text{10.811 g/mol + 57.00 g/mol = 67.81 g/mol}}$