What is the empirical formula a for a compound that is 15.3% magnesium, 44.5% chlorine, and 40.2 % oxygen

Explanation:

When calculating an empirical formula from percentages, assume you have a 100g sample. This allows you to convert the percentages directly to grams, because X % of 100g is X grams.

So:

15.3 % = 15.3g Mg, 44.5% = 44.5g Cl, 40.2% = 40.2g O

The next step is to divide each mass by their molar mass to convert your grams to moles.

15.3/24.3 = .630 mol

44.5/35.5 = 1.25 mol

40.2/16.0 = 2.5 mol

Then you will divide all of your mol values by the SMALLEST number of moles. This gives you whole numbers that are the mole ratio (subscripts) of the empirical formula.

.630 mol/.630mol = 1

1.25 mol/.630mol = 2

2.5 mol/.630mol = 4

So the empirical formula is

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.