A sample of an oxide of antimony (Sb) contained 25.0 g of antimony combined with 8.2 g of oxygen. The simplest formula for the oxide is?

Answer 1

Convert 25.0 g Sb to moles.
Convert 8.2 g oxygen to moles.
Find the ratio of one element to the other in small whole numbers. The easiest way to do that is to divide the smaller number of moles by itself. That assures a 1.000 for that numbers. Then divide the other by the same small whole number, round to whole numbers and that should be the empirical formula. [Note: In rounding to a whole number, be careful that you don't "round" too much; i.e., a 0.25 could become a whole number by multiplying everything by 4, a 0.5 could become a whole number by multiplying everything by 2, etc).