Definitions Flashcards
Enthalpy of formation
Enthalpy change when one mole of a substance is formed from its constituent elements with all reactants and products in standard states under standard conditions.
Enthalpy of combustion
Enthalpy change when 1 mole of a substance is completely burned in oxygen with all reactants and products in standard states under standard conditions.
Enthalpy of neutralisation
Enthalpy change when one mole of water is formed in a reaction between an acid and an alkali under standard conditions.
Hess’s law
The enthalpy change for a reaction is independent of the route taken.
Relative atomic mass (Ar)
The average mass of an atom of an element compared to 1/12th the mass of an atom of carbon-12.
Relative molecular mass (Mr)
The average mass of a molecule compared to 1/12th the mass of an atom of carbon-12.
Avogadro constant
The number of particles in a mole.
Empirical formula
The simplest whole number ratio of atoms of each element in a compound.
Molecular formula
The actual number of atoms of each element in a compound.
Relative isotopic mass
The mass of an atom of an isotope of an element compared to 1/12th the mass of an atom of carbon-12.
First ionisation energy
The enthalpy change (KJ/mol) when one mole of gaseous atoms form one mole of gaseous ions with a single positive charge.
Enthalpy change
Heat change at constant pressure.
Coordinate / dative covalent bond
A covalent bond where both shared electrons have originated from one atom.
Electronegativity
the ability of an atom to withdraw electron density in a covalent bond.
Van der Waals forces
Temporary induced dipole-dipole interactions. (Weakest IMF)
