Science 20: Chemistry - Moles and Mole Ratios

Flashcards covering key concepts from Chemistry Topic 3 on Moles and Mole Ratios.

Mole

The SI base unit that measures the amount of a substance, equal to 6.02 x 10²³ elementary entities.

Avogadro's number

The number 6.02 x 10²³, which defines the number of particles in one mole of a substance.

Molar mass

The mass, in grams, of one mole of a substance, measured in g/mol.

Mass vs Molar Mass

Mass refers to the amount of matter in an object, while molar mass refers to the mass per mole of a substance.

Coefficient in a chemical equation

A number that represents the number of moles of a substance in a chemical reaction.

Mole ratio

The ratio of coefficients in a balanced chemical equation that indicates the proportions of reactants and products.

Determining moles

Using the formula n = m/M, where n is the number of moles, m is the mass of the substance, and M is its molar mass.

Chemical reaction

A process in which substances (reactants) are transformed into different substances (products) through the breaking and forming of chemical bonds.

Example of mole ratio

In the reaction 4Ag + 2H₂S + O₂ → 2Ag₂S + 2H₂O, the mole ratio of silver (Ag) to silver sulfide (Ag₂S) is 4:2.

Calculating molar mass of NaCl

Add the molar masses of sodium (Na) and chlorine (Cl) to find the molar mass of sodium chloride (NaCl): 22.99 g/mol + 35.45 g/mol = 58.44 g/mol.

Balance a chemical equation

To ensure that the number of atoms of each element is the same on both sides of the equation.

Universal physical constant of moles

A mole is defined as the amount of a substance that contains as many elementary entities as the number of atoms in 12 grams of carbon-12.