Moles

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, ions, etc.) as there are in 12 grams of carbon-12.

Front

How do you calculate the number of moles from mass?

Back

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

Front

What is the molar mass of a compound?

Back

The molar mass of a compound is the mass of one mole of that compound, calculated by summing the atomic masses of all the atoms in its chemical formula.

Front

How many molecules are in one mole of a substance?

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

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

How do you determine the empirical formula from mass percentages?

Back

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

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What is the difference between empirical and molecular formulas?

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

Front

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

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Mass = number of moles x molar mass.

Front

What is the significance of Avogadro's number?

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Avogadro's number allows chemists to convert between moles and number of particles (atoms, molecules) in a substance.

Front

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

Back

Mass = moles x molar mass of the compound.