Percent Composition

Front

What is percent composition?

Back

Percent composition is the percentage by mass of each element in a compound, calculated by dividing the mass of the element by the total mass of the compound and multiplying by 100.

Front

How do you calculate the percent composition of an element in a compound?

Back

Percent composition = (mass of element in 1 mole of compound / molar mass of compound) x 100.

Front

What is the percent by mass of fluorine in CaF2 (gram-formula mass = 78 g/mol)?

Back

49%.

Front

What is the percent composition by mass of oxygen in MgSO4 (gram formula mass = 120 g/mol)?

Back

53%.

Front

What is the percent composition of Benzene, C6H6?

Back

C = 92.2%, H = 7.8%.

Front

In which compound is the percent composition by mass of Cl equal to 42%?

Back

HClO3 (gram formula mass = 84 g/mol).

Front

What is the percent by mass of magnesium in MgO?

Back

60%.

Front

What is the formula for calculating the mass percent of an element?

Back

Mass percent = (mass of element / total mass of compound) x 100.

Front

What is the molar mass of CaF2?

Back

The molar mass of CaF2 is 78 g/mol.

Front

If a compound has a molar mass of 100 g/mol and contains 20 g of oxygen, what is the percent composition of oxygen?

Back

Percent composition of oxygen = (20 g / 100 g) x 100 = 20%.