Empirical Formulas and Molecular Structures

Front

What is an empirical formula?

Back

An empirical formula is the simplest whole-number ratio of elements in a compound.

Front

How do you calculate percent by mass of an element in a compound?

Back

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

Front

What is the molar mass of MgO?

Back

Molar mass of MgO = 24.31 g/mol (Mg) + 16.00 g/mol (O) = 40.31 g/mol.

Front

What is the percent by mass of magnesium in MgO?

Back

60%.

Front

What is the percent composition by mass of sulfur in MgSO4?

Back

26.64%.

Front

How do you determine which solution is more concentrated?

Back

Concentration = mass of solute / volume of solution. Compare the ratios.

Front

What is the molar mass of C6H12?

Back

Molar mass of C6H12 = (6 x 12.01 g/mol) + (12 x 1.008 g/mol) = 84.16 g/mol.

Front

How do you calculate the mass of a substance from moles?

Back

Mass = moles x molar mass.

Front

What is the mass of 4.20 moles of C6H12?

Back

353 g.

Front

What is a molecular formula?

Back

A molecular formula shows the actual number of atoms of each element in a molecule.