Mole REVIEW

Front

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

Back

27%.

Front

What is a molecular formula?

Back

A molecular formula shows the number of each type of atom in a molecule, e.g., CH2O.

Front

How do you calculate the number of moles from grams?

Back

Number of moles = mass (g) / molar mass (g/mol).

Front

What is the empirical formula?

Back

The simplest whole-number ratio of atoms in a compound.

Front

What is the molar mass of Al(OH)3?

Back

Al: 27 g/mol, O: 16 g/mol, H: 1 g/mol; Molar mass = 78 g/mol.

Front

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

Back

(mass of element in 1 mol of compound / molar mass of compound) x 100.

Front

What is the empirical mass of CF2?

Back

Empirical mass = 12 (C) + 19 (F) x 2 = 50 g/mol.

Front

What is the molecular formula if the molecular mass is 200.04 g/mol and the empirical formula is CF2?

Back

C4F8.

Front

What is the significance of the molecular formula?

Back

It indicates the actual number of atoms of each element in a molecule.

Front

How do you determine if a formula is a molecular formula or an empirical formula?

Back

A molecular formula is a multiple of the empirical formula.