F325 Flashcards
Acid dissociation constant
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Bond dissociation enthalpy
The enthalpy change that takes place when breaking by homolytic fission 1 mol of a given bond in the molecules of a gaseous species.
Acid–base pair
A species that is a proton, H+, donor. A pair of two species that transform into each other by gain or loss of a proton.
Brønsted–Lowry acid
A species that is a proton, H+, donor.
Activation energy
A species that is a proton, H+, acceptor. The minimum energy required to start a reaction by the breaking of bonds.
Brønsted–Lowry base
A species that is a proton, H+, acceptor.
Adsorption
The process that occurs when a gas, liquid orsolute is held to the surface of a solid or, more rarely, aliquid.
Buffer solution
A system that minimises pH changes on addition of small amounts of an acid or a base.
Alkali
A type of base that dissolves in water to form hydroxide ions, OH- (aq) ions.
Catalyst
A substance that increases the rate of a chemical reaction without being used up in the process.
Average bond enthalpy
The average enthalpy change that takes place when breaking by homolytic fission 1 mol of a given type of bond in the molecules of a gaseous species.
Complex ion
A transition metal ion bonded to one or more ligands by coordinate bonds (dative covalent bonds).
Boltzmann distribution
A diagram showing the distribution of energies of the molecules at a particular temperature.
Conjugate acid
A species formed when a proton is added to a base.
Conjugate base
A species formed when a proton is
added to an acid.
Electron shielding
The repulsion between electrons in different inner shells. Shielding reduces the net attractive force from the positive nucleus on the outer shell electrons.
Coordination number
The total number of coordinate bonds formed between the central metal ion and any ligands.
Electronegativity
A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond.
Displacement reaction
A reaction in which a more reactive element displaces a less reactive element from an aqueous solution of its ions.
End point
The point in a titration at which there are equal concentrations of the weak acid and conjugate base forms of the indicator. The colour at the end point is midway between the colours of the acid and conjugate base forms.
Disproportionation
The oxidation and reduction of the same species in a redox reaction.
Endothermic
A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surrounding.
Dynamic equilibrium
The equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction.
(Standard) enthalpy change
of atomisation
The enthalpy change that takes place when one mole of gaseous atoms forms from the element in its standard state.
(First) electron affinity
The enthalpy change required to add one electron to each atom in one mole of gaseous atoms to form one mole of gaseous 1– ions.
(Standard) enthalpy change of
combustion
The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions, all reactants and products being in their standard states.
(Second) electron affinity
The enthalpy change required to add one electron to each ion in one mole of gaseous 1– ions to form one mole of gaseous 2– ions.
(Standard) enthalpy change of formation
The enthalpy change that takes place when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.
(Standard) enthalpy change of hydration
The enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in water, forming one mole of aqueous ions, under standard conditions.
Entropy, S
The quantitative measure of the degree of disorder in a system.
(Standard) enthalpy change of neutralisation
The energy change that accompanies the neutralisation of an aqueous acid by an aqueous base to form one mole of H2O(l), under standard conditions.
(Standard) entropy change of
reaction
The entropy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standard states.