U5 Exam on Moles

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

How do you calculate the molar mass of a compound?

Back

To calculate the molar mass, sum the atomic masses of all the atoms in the molecular formula of the compound, expressed in grams per mole.

Front

What is the relationship between moles and mass?

Back

Mass (in grams) = Number of moles x Molar mass (g/mol).

Front

What is percent composition by mass?

Back

Percent composition by mass is the percentage by mass of each element in a compound, calculated as (mass of element in 1 mole of compound / molar mass of compound) x 100%.

Front

What is the empirical formula?

Back

The empirical formula is the simplest whole-number ratio of atoms of each element in a compound.

Front

What is the molecular formula?

Back

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

Front

How do you convert grams to moles?

Back

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

Front

What is the significance of Avogadro's number?

Back

Avogadro's number (6.022 x 10^23) is the number of particles in one mole of a substance, allowing chemists to count particles by weighing them.

Front

How do you find the number of moles in a given mass of a substance?

Back

Number of moles = Mass of substance (g) / Molar mass (g/mol).

Front

What is the formula for calculating the mass of a substance from moles?

Back

Mass = Moles x Molar mass.