A level Physical Chemistry Key Definitions (Incomplete)

Question	Answer
Acid dissociation constant, Ka	The extent of acid dissociation. Ka = {(conc.H+)(conc.A-)}/ (conc. HA)
Ionic product of water Kw	The equilibrium constant for the dissociation of water into H+ and OH- ions.
Buffer	Minimises changes in pH when diluted or when small ampounts of strong acid/ base are added.
Salt	Ionic product formed when an acid reacts with a base and the H+ from the acid is replaced by another positive ion.
Monoprotic	Produces one mole of H+ ions in solution.
Diprotic	Produces two moles of H+ ions in solution.
Weak Acid	Proton donor that partially dissociates into its ions.
Weak Base	Proton acceptor that partially dissociates into solution.
Strong Acid	Proton Donor that completely dissociates into its ions.
pH	A measure of acidity according to the concentration of H+ ions in the solution.
Amphoteric	Can act as both acid and base.
Amphiprotic	Can both donate and accept a proton.
Conjugate acid base pair	A pair of species differing only by a single proton.
Alkali	Soluble base which releases OH- ions in solution.
Bronsted-Lowry Acid	Releases H+ ions in solution
Bronsted-lowry base	Proton acceptor.
Standard enthalpy change of reaction.	The enthalpy change that accompanies a reaction in the molar quantities expressed in the balanced equation, under standard conditions.
Standard enthalpy change of combustion.	The enthalpy change that takes place when one mole of a compound is reacted completely with oxygen, under standard conditions.

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	Created by Irene Binil over 6 years ago