Question

Which is the molar mass of `BF_3`?

Answer 1

`color(navy)("67.81 g/mol")`

Explanation:

`color(brown)"We will use the formula below to answer the question:"`

**`"number of atoms given by subscript"` `xx` `"atomic weight of element"` `=` 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:

`color(blue) ("10.811 g/mol + 57.00 g/mol = 67.81 g/mol")`