A compound of carbon and bromine contains 6.99% carbon and has a molar mass of 515.4 g/mol. What is the empirical formula of this compound?

Question

cuanchi · Answer

with the percentage of carbon and the molar mass you can calculate the mass of carbon per mol of the compound. Then with this value you can calculate the number of moles of carbon per mole of the compound by using the atomic mass of carbon.
If you calculate the difference of mass between the compound and the mass of carbon you will have the mass of bromine. If you now divide the mass of bromide by the atomic mass of bromide you will find the number of moles of bromide by mole of the compound. 
Whit the number of mole of carbon and the number of mol of bromide you can write your formula

cuanchi · Answer

because the problem is asking you the empirical formula if you can you have to simplify the sub-index in the molecular formula