The Mole

Front

What is a mole in chemistry?

Back

A mole is a unit of measurement used to express amounts of a chemical substance, defined as exactly 6.022 x 10^23 particles (atoms, molecules, ions, etc.).

Front

What is molar mass?

Back

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all atoms in a molecule.

Front

How do you calculate the molar mass of a compound?

Back

To calculate the molar mass, multiply the atomic mass of each element by the number of atoms of that element in the compound, then sum all the values.

Front

What is the empirical formula?

Back

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

Front

How do you determine the empirical formula from percentage composition?

Back

Convert the percentage of each element to grams, then to moles, and find the simplest ratio of moles of each element.

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

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 moles to grams?

Back

To convert moles to grams, multiply the number of moles by the molar mass of the substance.

Front

What is the formula for calculating the number of moles?

Back

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

Front

What is the significance of Avogadro's number?

Back

Avogadro's number (6.022 x 10^23) allows chemists to count particles by weighing them, linking the macroscopic and microscopic worlds.