Ch 10: Acids and Bases Flashcards
Arrhenius acids
dissociate to produce excess hydrogen ions in soln
Arrhenius bases
dissociate to produce excess hydroxide ions in soln
Bronsted-Lowry acids
species that can donate hydrogen ions
Bronsted-Lowry bases
electron-pair donors
all ____ are Bronsted-Lowry acids and bases, and all Bronsted-Lowry acids and bases are ____ but the reverse of this is not true
Arrhenius acids and bases
Lewis acids and bases
Lewis acids are
electron-pair acceptors
Lewis bases are
electron-pair donors
amphoteric
behave as acid or base
amphiprotic species are
amphoteric species that specifically can behave as Bronsted-Lowry acids and bases
ex: water
conjugate species of polyvalent acids and bases can behave as
amphoteric and amphiprotic species
water dissociation constant, Kw
10^-14 at 298K
like other equilibrium constants, only affected by temperature
pH and pOH =
14 at 298K
strong acids and bases
complete dissociate
weak acids and bases
do not completely dissociate and have dissociation constants (Ka and Kb)
Neutralization reactions
form salts and sometimes water
equivalent is defined as
one mole of the species of interest
in acid-base chemistry, normality is
the concentration of acid or base equivalents in solution
polyvalent acids and bases
those that can donate or accept multiple electrons. The normality of a solution containing a polyvalent species is the molarity of the acid or base times the number of protons it can donate or accept
titrations
used to determine the concentration of a known reactant in the solution
titrant
known concentration and is added slowly to the titrand to reach the equivalence point
titrand
unknown concentration but a known volume
half-equivalence point
midpoint of the buffering region, which half of the titrant has been protonated (or deprotonated); thus [HA] = [A-] and a buffer is formed
equivalence point
indicated by the steepest slope in a titration curve; it is reached when the number of acid equivalents in the original solution equals the number of base equivalents added, or vice-versa
strong acid and strong base titrations have equivalence points at
pH = 7
weak acid and strong base titrations have equivalence points at
ph > 7
strong acid and weak base titrations have equivalence points at
ph
weak acid and weak base titrations can have equivalence points
above or below 7, depending on the relative strength of the acid or base
indicators are
weak acids or bases that display different colors in their protonated and deprotonated forms
indicator chosen for a titration should have a pKa close to the pH of the expected equivalency point
endpoint of a titration
is when the indicator reaches its final color
multiple buffering regions and equivalence points are
observed in polyvalent acid and base titrations
buffer solutions
consist of a mixture of a weak acid and its conjugate salt or a weak base and its conjugate salt; they resist large fluctuations in pH
buffering capacity
refers to the ability of a buffer to resist changes in pH; maximizing buffering capacity is seen within 1 pH point of the pKa of the acid in the buffer solution
Henderson-Hasselbach equation
quantifies the relationship between pH and pKa for weak acids and between pOH and pKb for weak bases; when a solution is optimally buffered pH = pKa and pOH = pKb
