Acids and Bases Flashcards
Arrhenius acid
anything that produces hydrogen ions in aqueous solution
Arrhenius base
anything that produces hydroxide ions in aqueous solution
Bronsted and Lowry
acids - anything that donates a proton
bases - anything that accepts a proton
Lewis acids and bases
acids - anything that accepts a pair of electrons
bases - anything that donates a pair of electrons
*most general definition
pH =
pH = -log[H+]
log(1) =
0
log(10) =
1
log(AB) =
log(A) + log(B)
hydronium ion
H3O+
conjugate acid and base
the products that correspond to acid and base
HA is conjugate acid of base A-
A- is conjugate base of acid HA
*stronger the acid, weaker the conjugate base
stronger the base, weaker the conjugate acid
weak acid - strong or weak conjugate
amphoteric
act as acid or base,depending on their environment
strong acids
hydroionic acid - HI hydrobromic acid - HBr hydrochloric acid -HCl nitric acid - HNO3 perchloric acid - HClO4 chloric acid - HCLO3 sulfuric acid - H2SO4
strong bases
sodium hydroxide - NaOH potassium hydroxide - KOH amide ion - NH2- hydride ion - H- calcium hydroxide - Ca(OH)2 sodium oxide - Na2O calcium oxide - CaO
polyprotic acids
can donate more than 1 proton
diprotic- can donate 2 electrons
3 factors that deterime if molecule will release its hydrogen into solution and act as an acid
strength of bond holding hydrogen
polarity of bond
stability of conjugate base
with oxyacids, more oxygens means ….
stronger acid
hydrides
binary compounds containing hydrogen
basic, acid, or neutral
metal hydrides are…
basic or neutral
nonmetal hydrides are…
acidic or neutral
increasing acidity to the right and down the table
autoionization of water
H2O + H2O –> H3O+ + OH-
K(_w) is equilibrium constant
K(_w)
equilibrium constant for autoionization of water
= [H+][OH-]
= 10^-14 at 25C
pH + pOH =
pK(_w) = 14
acid dissociation constant, K(_a)
base dissociation constant, K(_b)
acid/base’s equilibrium constant in water
K(_a)K(_b) = K(_w)q
pK(_a) + pK(_b) =
pK(_w) = 14
K_a and pK_a for strong acid
K_a great than 1
pK_a less than zero
salts
ionic compounds that dissociate in water
titration
drop by drop mixing of an acid and base
to find the concentration of an unknown by comparing it with the titrant (added drop by drop)
titration curve
sigmoidal curve
equivalence point/stoichiometric point of titration curve
midpoint of vertical part of titration curve, equal equivalents of acid and base in solution
for equally strong acid-base titrations, equivalence point will be at pH _
pH 7
titration curve of weak acid with strong base
2 flat parts, equivalence point not as predictable
half equivalence point
point where exactly half of the acid has become base, concentration of acid is equal to concentration of its conjugate base
at midpoint of section of graph that is most like horizontal line
can add largest amount of base or acid with least change in pH
where solution is most buffered
pH of solution = pK_a of acid
buffered
can add largest amount of base or acid with least change in pH
Henderson-Hasselbalch equation
pH = pK_a + log([A-]/[HA])
pH of solution = pK_a of acid at half equivalence point (log1 = 0)
to make buffer solution, start with acid whose pK_a is
closest to pH at which want the buffer solution
mix equal amount of acid with its conjugate base
buffer solution is made from…
equal and copious amounts of weak acid and its conjugate base
adding a small amount of water to and ideally dilute buffered solution will…
have no effect on the pH
indicator used to find the ___
equivalence point
indicator is usually…
weak acid whose conjugate base is a different color
indicator range
pH values of the two points of color change
can be predicted from Henderson-hasselbalch
point where indicator changes color is the ___
endpoint
which indicator to use?
one with pK_a as close as possible to pH of the titrations equivalence point
polyprotic titration
more than one equivalence point
first proton completely dissociates before 2nd begins to dissociate
