In Chemistry, the Periodic Table is the source of all knowledge. Look on it for the information you need. B = 11 grams / mol F = 19 grams / mol This stuff has a formula of BF3. The 3 only affects the F. There is 1 Boron and 3 florines. If you want a number to affect the Boron, use brackets. In this case, we don't. BF3 = 11 + 3*19 = 11 + 57 = 68 grams / mol
