weak acid/ base ionization (incompletely forming a dynamic equilibrium)
amphoteric/amphiprotic
in the bronsted lowry theory a substance capable of acting as an acid or base in different chemiccal reactions (a substance that may donate or accept a proton)
ex. baking soda HCO3
could become H2CO3 and OH
or CO3 and H3O
conjugate acid base pair
two substances whos formulas differe only by one H unit
a competition for protons
when a strong acid reacts with water the transter of protons is coplete in the forward direction and almost no transfer of protons occur via the reverse reaction (100% complete)
-high percent reaction
-products are favoured
-low attraction ofr its proton and donates to base
stronger acid
has weaker conjugate base
weaker acid
stronger conjugate base
weak acids
have lower % reaction ionization (reactants are favoured)
strong base
strong attraction to protons
autoionization of water
water molecules react with each toher and produce OH and H3O
reaction between 2 H20 molelcules producting a H3O ion and OH ion
ionization process
where one proton is transferred from one to the other they dont dissociate
ion product constant for water
kw equilibruim constant for the ionization of water 1.0x10^-14
[h] = [oh]
=1.0x10-7
weak acids
acid that partially ionizes in solution but exists primarilly in thre form of molecules
examples of weak acids
natural acids (organic)
and some inorganic are:
HF H2CO3
H2S
H3BO3
weak bases
a base that has a weak attraction for protons
le chaletlier OH shifts equilibruim left in iautoionization of water and HP is greater than 7
-proton acceptors
-reacts non quantitatively incomletely
-compound must possess an atom with a lone pair of valence electrons to accept H from water
examples of weak bases
NH3 and Na3PO4
the stronger the acid
the weaker the conjugate base and vice versa
Ionization constants
ka contstant for acids
kb constant for bases
kw constant for water
Kw=kakb
polyprotic acids
an acid with more than one ionizable acidic proton
ionize in steps
release one H at a time
each ionization reaction has its own constant Ka1 Ka2... etc
salt
solit
anion+cat ion in crystalline lattice
dissoiate into indicidual hydrated ions
neutral salt
salts that consist of cations of strong bases and anions of strong acids have no effect on PH
nacl --> na + cl (both ions dont hydrolize therefore it is neutral)
hydrolysis
a reaction of an ion with water to produce an acidic or basic solution (H3O or OH)
salts that form acidic solutions
cations that are conjugate acids of weak bases atct as weak acids and lower PH
(NH4 andN2H5)
NH4+H20 --> H3O +NH3
group 1 and 2
dont form acidic solutions except for Be
only high charged ions do for acidic solutions for example Al+3
salts that form basic solutions
an anion of a weak acid is strong enough to affect the PH (conjugate base of weak acid)
ex Na C2H3O2 --> Na + C2H3O2
C2H3O2 +H20 --> HC2H3O2 + OH
SALTS that act as acids and bases
if the ka of the acid is > than kb of the base it will be acidic PH <7
Kb>Ka it will be basic PH >7
Kb=Ka it will be neutral PH =7
titration
the precise addition of a solution in a buret into a measured volume of a sample solution
titrant
the solution in a buret during a titration
sample
the solution being analyzed
primary standard
a chemical available in a pure and stable form for which an accurate concetnration can be prepared the solution is then used to determine precisely by means of titratrating the concentration of a titrant
equivalence point
in a titration the measured quantity of titrant recorded at the point at which chemically equivalent amounts have reacted
end point
the point in a titration at which a sharp change in a measureable charateristic property occurs ex colour change in an indicator
titrating a strong acid with a weak base
ph at eq point is less than 7
conjugate acid of weak base
stong base strong acid
ph at eq point is 7
autoionization of water
strong base weak acid
ph is greater than 7
conjugate base of weak acid
buffers
all ph curves witha a weak acid or weak base have a point where a buffering ation occurs
buffer definition
a mixture of a conjugate acid base pair that maintains a nearly constant PH when diluted or when a strong acid or base is added and equal mixture of a weak acid and its conjugate base