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 percent composition?

Back

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

Front

What is the percent by mass of sodium in NaCl?

Back

39%.

Front

What is the percent by mass of oxygen in MgO?

Back

40%.

Front

Which of the following is NOT needed to calculate percent composition?

Back

Avogadro's Number.

Front

Which element in KCN has a percent composition of 60.0%?

Back

K.

Front

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

Back

49%.

Front

What is the molar mass of NaCl?

Back

58.44 g/mol.

Front

What is the molar mass of MgO?

Back

40.31 g/mol.

Front

If a compound has a molar mass of 100 g/mol and contains 25 g of carbon, what is the percent composition of carbon?

Back

25%.