How do you determine the molar mass of #BF_3#?

1 Answer
Jul 17, 2016

#color(hotpink)("67.81 g/mol")#


#color(purple)"We will use the formula below to answer the question:"#

atomic weight of element #xx#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:

#color(red) ("10.811 g/mol + 57.00 g/mol = 67.81 g/mol")#