Moles Review

Front

What is a mole in chemistry?

Back

A mole is a unit of measurement used to express the amount of a substance. It is defined as the amount of substance that contains as many entities (atoms, molecules, etc.) as there are in 12 grams of carbon-12.

Front

How many atoms are in 1 mole of any substance?

Back

1 mole of any substance contains approximately 6.022 x 10^23 atoms, known as Avogadro's number.

Front

What is the empirical formula?

Back

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

Front

How do you calculate the empirical formula from percent composition?

Back

1. Convert the percentage of each element to grams. 2. Convert grams to moles by dividing by the atomic mass. 3. Divide by the smallest number of moles to find the ratio.

Front

What is the molecular formula?

Back

The molecular formula shows the actual number of atoms of each element in a molecule, which may be a multiple of the empirical formula.

Front

How do you determine the molecular formula from the empirical formula?

Back

To find the molecular formula, divide the molar mass of the compound by the molar mass of the empirical formula, then multiply the subscripts in the empirical formula by this ratio.

Front

What is the difference between empirical and molecular formulas?

Back

The empirical formula represents the simplest ratio of elements, while the molecular formula shows the actual number of atoms in a molecule.

Front

How do you convert grams of a substance to moles?

Back

To convert grams to moles, divide the mass of the substance by its molar mass (grams/molar mass).

Front

What is the molar mass of water (H2O)?

Back

The molar mass of water is approximately 18.02 g/mol.

Front

How many molecules are in 1 mole of water?

Back

1 mole of water contains approximately 6.022 x 10^23 molecules.