Percent Composition By Mass

How is the percent composition by mass of an element in a compound calculated?

• (Total molar mass of the element / Molar mass of the whole compound) * 100%

• (Molar mass of the whole compound / Total molar mass of the element) * 100%

• (Total molar mass of the element + Molar mass of the whole compound) * 100%

• (Total molar mass of the element * Molar mass of the whole compound) / 100%

What is the percent composition by mass of Hydrogen in H2O? (Atomic mass of H = 1.01 g/mol, O = 16.00 g/mol)

• 11.2%

• 88.8%

• 2.02%

• 18.02%

Calculate the percent composition by mass of Iron in FeCl3. (Atomic mass of Fe = 55.85 g/mol, Cl = 35.45 g/mol)

• 65.57%

• 34.43%

• 55.85%

• 162.2%

Determine the percent composition by mass of Carbon in C6H10O4. (Atomic mass of C = 12.01 g/mol, H = 1.01 g/mol, O = 16.00 g/mol)

• 72.06%

• 146.2%

• 49.29%

• 50.71%