Mole, Empirical and Molecular Formulas

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What is a mole in chemistry?

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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.

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What is an empirical formula?

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

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What is a molecular formula?

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

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

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To find the empirical formula, divide the subscripts in the molecular formula by their greatest common divisor.

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What is the percent composition of an element in a compound?

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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 by the total molar mass of the compound and multiplying by 100.

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How do you calculate the molar mass of a compound?

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To calculate the molar mass, sum the atomic masses of all the atoms in the molecular formula.

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What is the significance of a balanced chemical equation?

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A balanced chemical equation provides the mole ratio of reactants and products, which is essential for stoichiometric calculations.

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How many moles are in 18 grams of water (H2O)?

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To find the number of moles, divide the mass of the substance by its molar mass. For water, molar mass = 18 g/mol, so 18 g H2O = 1 mole.

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What is the relationship between moles and volume for gases at STP?

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At standard temperature and pressure (STP), 1 mole of any gas occupies 22.4 liters.

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What is the formula for calculating percent composition?

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