How do you calculate percent composition in chemistry?

Percent composition is an important concept in chemistry that measures the percentage by mass of each element in a compound. It is calculated by dividing the mass of each element by the total mass of the compound, then multiplying by 100. The resulting percentage represents the relative mass of each element in the compound.

To calculate the percent composition of a compound, you first need to determine the molar mass of the compound by adding up the atomic masses of all the elements in the compound. Then, you can calculate the mass of each element in the compound by multiplying the number of atoms of that element by its atomic mass. Once you have the mass of each element, you can calculate the percent composition by dividing the mass of each element by the total mass of the compound and multiplying by 100.

For example, let's calculate the percent composition of water (H₂O). The molar mass of water is 18.015 g/mol. The mass of hydrogen in water is 2.016 g/mol (2 atoms x 1.008 g/mol) and the mass of oxygen is 15.999 g/mol (1 atom x 15.999 g/mol). To calculate the percent composition of hydrogen in water, divide the mass of hydrogen by the total mass of the compound and multiply by 100: (2.016 g/mol / 18.015 g/mol) x 100 = 11.19%. To calculate the percent composition of oxygen in water, divide the mass of oxygen by the total mass of the compound and multiply by 100: (15.999 g/mol / 18.015 g/mol) x 100 = 88.81%.