Welcome to Chemistry!!

Candy Question You will be given a package of candy. It is your job to find the mass percent of each color. Remember that percents are written as a partial amount out of a whole amount: Example: 50/100 = 50% ¾ = 75%

Candy Question We can use this same technique to find the mass percent in different compounds.

Percent Composition We can use the information from the formula of compound to find the percent composition We use the mass of each element in 1 mole of the compound

Percent Composition For example, we are going to use the compound ethanol with the formula C2H5OH First find the molecular weight of ethanol

Percent Composition Mass of C = 12.01 x 2 = 24.02 Mass of H = 1.008 x 6 = 6.048 Mass of O = 16.00 x 1 = 16.00 Sum = 46.07g = molecular mass

Percent Composition Solve for mass percent of each element MP of C = 24.02/46.07 x 100% MP of C = 52.14%

Percent Composition MP of H = 6.048/46.07 x 100% MP of H = 13.13% MP of O = 16.00/46.07 x 100% MP of O = 34.73%

Percent Composition The easiest way to check is to make sure that all your percents total 100%!!!