Chemical Calculations

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Mole Ratio Noun

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[mohl rey-shee-oh]

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Mole Ratio

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A conversion factor derived from the coefficients of a balanced chemical equation, used to relate moles of different substances.

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Example: This image shows a balanced chemical reaction. The mole ratio is the proportion of molecules; here, 1 methane molecule reacts with 2 oxygen molecules.

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Molar Mass Noun

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[moh-ler mas]

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Molar Mass

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The mass of one mole of a substance, typically expressed in grams per mole, used to convert between mass and moles.

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Example: This image shows that the molar mass of a compound (H₂O) is found by adding the individual atomic masses of its constituent atoms (two Hydrogen, one Oxygen).

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Stoichiometry Noun

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[stoy-kee-om-i-tree]

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Stoichiometry

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The area of chemistry that involves the calculation of quantities of reactants and products involved in chemical reactions.

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Example: This diagram shows that a chemical equation is like a recipe. Two molecules of hydrogen (2H₂) react with one molecule of oxygen (O₂) to produce exactly two molecules of water (2H₂O).

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STP (Standard Temperature and Pressure) Noun

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[es-tee-pee]

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STP (Standard Temperature and Pressure)

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A standard set of conditions, defined as 0°C and 1 atmosphere of pressure, used for measurements involving gases.

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Example: This image defines Standard Temperature and Pressure (STP) as 0°C and 1 atm, and shows that at these conditions, one mole of any gas has a volume of 22.4 liters.

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Molar Volume Noun

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[moh-ler vol-yoom]

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Molar Volume

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The volume occupied by one mole of a substance, which is 22.4 liters for any ideal gas at STP.

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Example: This formula triangle shows the relationship between the volume of a gas, its amount in moles, and the molar volume constant (24 dm³/mol).

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Representative Particles Noun

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[rep-ri-zen-tuh-tiv pahr-ti-kuhls]

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Representative Particles

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The smallest units in which a substance naturally exists, such as atoms, molecules, or formula units, used in stoichiometric calculations.

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Example: This image shows the calculation used to convert the mass of water in grams to the amount of water in moles, using its molar mass.

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Avogadro's Number Noun

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[ah-vuh-gah-drohz nuhm-ber]

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Avogadro's Number

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The number of representative particles in one mole of a substance, which is approximately 6.02 x 10²³ particles per mole.

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Example: This image shows that Avogadro's number (6.02 x 10^23) of carbon atoms has a mass of 12 grams, visually connecting the concept to weighing.

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Sodium Bicarbonate Noun

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[soh-dee-uhm bahy-kahr-buh-neyt]

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Sodium Bicarbonate

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The chemical compound with the formula NaHCO₃, commonly known as baking soda, which decomposes upon heating to produce gas.

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Example: This model shows a Sodium Bicarbonate molecule is made of one sodium (Na), one hydrogen (H), one carbon (C), and three oxygen (O) atoms.