Percent Composition Practice

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

To calculate the percent composition of an element, use the formula: (mass of element in 1 mole of compound / molar mass of compound) x 100.

Front

What is the percent composition of magnesium in Mg3(PO4)2?

Back

27.48% Mg.

Front

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

Back

20%.

Front

Find the percent composition of Cu2S.

Back

%Cu = 79.854%, %S = 20.145.

Front

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

Back

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

Front

If an element sample is 44% Zinc and has a mass of 5.0 g, what is the mass of Zinc in the sample?

Back

2.2 g.

Front

What is the formula for calculating mass percent?

Back

Mass percent = (mass of component / total mass of mixture) x 100.

Front

What is the molar mass of Mg3(PO4)2?

Back

The molar mass of Mg3(PO4)2 is approximately 262.86 g/mol.

Front

How do you find the mass of an element in a sample given its percent composition?

Back

Multiply the total mass of the sample by the percent composition (as a decimal).