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 / molar mass of compound) x 100.

Front

What is the percent composition by mass of magnesium in MgSO4 (molar mass = 120 g/mol)?

Back

20%.

Front

What is the percent composition by mass of sulfur in MgSO4 (molar mass = 120 g/mol)?

Back

27%.

Front

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

Back

53%.

Front

What is the molar mass of CaF2?

Back

78 g/mol.

Front

What is the percent by mass of calcium in CaF2 (molar mass = 78 g/mol)?

Back

51%.

Front

What is the percent composition by mass of chlorine in HClO3 (molar mass = 84 g/mol)?

Back

42%.

Front

How do you find the molar mass of a compound?

Back

Add the atomic masses of all the atoms in the compound's formula.

Front

What is the percent composition of an element if its mass is equal to the total mass of the compound?

Back

100%.