Final answer:
Percent composition in chemistry refers to the proportion of each element within a compound by mass. It can be used to verify the Law of Multiple Proportions and to determine empirical formulas by providing the mass ratios of the elements in a compound.
Step-by-step explanation:
Understanding Percent Composition in Compounds
The concept of percent composition is crucial in chemistry as it represents the proportion, by mass, of each element within a compound. This property is used to determine the mass of individual elements in a given mass of the compound.
For example, consider a compound containing carbon and oxygen. If we have two such compounds where the first has 42.9% carbon and 57.1% oxygen, and the second has 27.3% carbon and 72.7% oxygen, we can apply the Law of Multiple Proportions. This law states that when two elements form more than one compound, the ratios of the masses of the second element that combine with a fixed mass of the first element are simple whole numbers.
In this scenario, if we calculate the mass ratios of oxygen to carbon for both compounds, we find that the oxygen masses combine with a fixed amount of carbon in a 2:1 ratio. Thus, it is consistent with the Law of Multiple Proportions. Furthermore, to determine the empirical formula of a compound, such as one with 69.94% iron and 30.06% oxygen, we divide the percent composition by the atomic mass of each element and express the result as the simplest whole number ratio.