Amount of substance key terms

relative atomic mass

The weighted average mass of an element's isotopes compared to one twelfth of the mass of a carbon-12 atom.

carbon-12

The standard isotope of carbon used to define the relative atomic mass scale, with an atomic mass of exactly 12 units.

relative molecular mass

The mass of a molecule relative to carbon-12, calculated by summing the relative atomic masses of all atoms in the molecular formula.

carbon-12

The standard isotope of carbon used to define the relative atomic mass scale, with an atomic mass of exactly 12 units.

relative formula mass

The sum of the relative atomic masses of all atoms in a formula, used to calculate the mass of ionic compounds.

ionic compound

A compound formed from the electrostatic attraction between positively and negatively charged ions.

relative molecular mass

The mass of a molecule calculated as the sum of the relative atomic masses of all atoms in the molecular formula, relative to carbon-12.

relative atomic mass

The weighted average mass of an atom of an element compared to one twelfth of the mass of a carbon-12 atom.

Avogadro constant

The number of particles in one mole, approximately 6.022 x 10^23. In The mole and the Avogadro constant, Avogadro constant is used to explain explain the Avogadro constant as the number of particles in one mole with A-Level Chemistry precision.

mole

A unit of measurement for amount of substance, defined as containing exactly 6.022 x 10^23 particles.

mole

A mole is the amount of substance that contains as many particles as there are atoms in exactly 12 grams of carbon-12.

Avogadro constant

The Avogadro constant is the number of particles in one mole of a substance, approximately 6.022 x 10^23 particles/mol.

Avogadro constant

The number of particles in one mole, approximately 6.022 x 10^23. In The mole and the Avogadro constant, Avogadro constant is used to explain calculate amounts using particle number and the Avogadro constant with A-Level Chemistry precision.

particle number

The total count of individual particles, such as atoms or molecules, in a sample. In The mole and the Avogadro constant, particle number is used to explain calculate amounts using particle number and the Avogadro constant with A-Level Chemistry precision.

mole

A mole is the amount of substance that contains the same number of entities as there are in 12 grams of carbon-12, approximately 6.022 x 10^23 particles.

relative molecular mass (Mr)

Relative molecular mass (Mr) is the sum of the relative atomic masses of all atoms in a molecular formula, calculated using the carbon-12 scale.

concentration

The amount of solute present in a given volume of solution, typically expressed in mol/dm³ or g/dm³.

moles

A unit of measurement for amount of substance, defined as the quantity containing the same number of entities as there are atoms in 12 grams of carbon-12.

mole

A unit of measurement used in chemistry to express amounts of a chemical substance, defined as the amount of substance that contains the same number of entities as there are in 12 grams of carbon-12.

Avogadro constant

The number of particles (atoms, molecules, ions, etc.) in one mole of a substance, approximately equal to 6.022 x 10^23.

Ideal Gas Equation

The equation pV = nRT relates pressure (p), volume (V), number of moles (n), ideal gas constant (R), and temperature (T) for an ideal gas.

Avogadro's Constant

Avogadro's constant is the number of particles in one mole, approximately 6.022 x 10^23 particles/mol.

Ideal Gas Equation

The equation pV = nRT relates pressure (p), volume (V), amount of gas (n), the gas constant (R), and temperature (T).

Rearranging the Ideal Gas Equation

The process of manipulating the ideal gas equation to solve for one variable, such as pressure, volume, or temperature.

Ideal Gas Equation

The equation pV = nRT relates pressure (p), volume (V), amount of gas (n), the gas constant (R), and temperature (T) in SI units.

SI Units

Standard International units used for measurements, including meters (m) for length, kilograms (kg) for mass, and Kelvin (K) for temperature.

unit consistency

The requirement that all units used in calculations must be compatible to ensure accurate results.

ideal gas calculations

Mathematical computations involving the ideal gas equation pV = nRT, which relate pressure, volume, temperature, and amount of gas.

empirical formula

The simplest whole-number ratio of atoms of each element in a compound. In Empirical and molecular formula, empirical formula is used to explain calculate empirical formulae from percentage composition data with A-Level Chemistry precision.

percentage composition

The mass percentage of each element in a compound, calculated from the formula.

empirical formula

The simplest whole-number ratio of atoms of each element in a compound. In Empirical and molecular formula, empirical formula is used to explain calculate empirical formulae from experimental mass data with A-Level Chemistry precision.

percentage composition

The percentage by mass of each element in a compound, calculated using the formula: (mass of element / molar mass of compound) x 100.

molecular formula

A representation of a compound that shows the number and type of atoms present in a molecule.

empirical formula

The simplest whole-number ratio of atoms of each element in a compound. In Empirical and molecular formula, empirical formula is used to explain derive molecular formulae from empirical formulae and relative molecular mass with A-Level Chemistry precision.

combustion analysis

A technique used to determine the empirical formula of a compound by burning it in excess oxygen and measuring the resulting products.

empirical formula

The simplest whole-number ratio of atoms of each element in a compound, derived from combustion analysis data.

empirical formula

The simplest whole-number ratio of atoms of each element in a compound. In Empirical and molecular formula, empirical formula is used to explain distinguish empirical formula from molecular formula with A-Level Chemistry precision.

molecular formula

The actual number of atoms of each element in a molecule of a compound. In Empirical and molecular formula, molecular formula is used to explain distinguish empirical formula from molecular formula with A-Level Chemistry precision.

balanced equation

An equation that shows the reactants and products of a chemical reaction with equal numbers of each type of atom on both sides.

reacting mass

The mass of a substance that participates in a chemical reaction, calculated using the molar mass and the amount in moles.

reacting mass

The mass of a reactant or product involved in a chemical reaction, calculated using a balanced equation.

balanced equation

An equation that shows the reactants and products of a chemical reaction with equal numbers of each type of atom on both sides.

limiting reagent

The reactant that is completely consumed in a chemical reaction, limiting the amount of product formed.

balanced equation

An equation that has the same number of atoms of each element on both sides, ensuring the law of conservation of mass is followed.

percentage yield

The ratio of the actual yield of a product to the theoretical yield, expressed as a percentage.

theoretical yield

The maximum amount of product that can be formed from the given amounts of reactants, calculated based on stoichiometry.

atom economy

A measure of the efficiency of a reaction, calculated as the ratio of the relative formula mass of the desired product to the sum of the relative formula masses of all products, expressed as a percentage.

percentage yield

The ratio of the actual yield of a product to the theoretical yield, multiplied by 100, indicating the efficiency of a reaction.

percentage yield

The ratio of the actual yield of a product to the theoretical yield, expressed as a percentage.

atom economy

A measure of the efficiency of a reaction in converting reactants into useful products, calculated as the relative formula mass of the desired product divided by the sum of the relative formula masses of all products.