Percent composition and empirical formula problems show all your work when solving the following problems. be sure to include units and label your answer.
1. find the empirical formula of a compound containing 32.0 g of bromine and 4.9 g of magnesium.

MgBr₂

Explanation:

Here we need to find the molar proportions of the two elements which will give us the empirical formula of the compound. To do that,we need  to determine the number of moles the grams given represent, and then convert them to whole numbers to find their proportions.

Atomic weght Br = 79.904 g/mol mol

⇒ mol Br = 32.0 g/ 79.904 g/mol = 0.40 mol

Atomic weight Mg = 24.305 g/mol  

⇒ mol Mg = 4.9 g/24.305 g/mol = 0.20 mol

Their proportions are

0.40 Br ÷ 0.20 Mg = 2 Br ÷ 1 Mg

Empirical formula = MgBr₂