The Mole 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 one mole of a substance?

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

Front

What is the molar mass of an element?

Back

The molar mass of an element is the mass of one mole of that element, typically expressed in grams per mole (g/mol). It is numerically equivalent to the atomic mass of the element in atomic mass units (amu).

Front

How do you calculate the number of moles from mass?

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

Front

What is the relationship between moles, mass, and molar mass?

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The relationship is given by the formula: mass = moles x molar mass.

Front

What is a chemical formula?

Back

A chemical formula is a way of expressing the composition of a compound using symbols for the elements and numerical subscripts to indicate the number of atoms of each element.

Front

How do you determine the number of atoms in a compound from its chemical formula?

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To determine the number of atoms in a compound, add the subscripts of all the elements in the chemical formula. For example, in C2H5OH, there are 2 (C) + 5 (H) + 1 (O) = 8 total atoms.

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What is the difference between empirical and molecular formulas?

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

Front

What is percent composition?

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Percent composition is the percentage by mass of each element in a compound, calculated by dividing the mass of the element in one mole of the compound by the molar mass of the compound and multiplying by 100.

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How do you find the percent composition of a compound?

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Percent composition = (mass of element in 1 mole of compound / molar mass of compound) x 100.