Studied by 25 peoplemake buffers with
weak acid and salt of conjugate base or vice versa
Group I and II metal cation with anion of a weak acid:
basic
Group I or II metals cations
neutral
factors affecting acid strength
H-A bond must be polarized w 8/S+ on H and 8/S- on A
acid stronger when bonds weaker
stable anion; stronger acid
determine pH of weak acid and strong base (equimolar)
from conjugate base of weak acid eq point, ICE for [OH], find Kb
Hydronium Ion
The H3O+ ion; a hydrated proton
7 Strong Acids
HCl, HBr, HI, HNO3, H2SO4, HClO4, HF
Strong Bases
soluble hydroxides (alkali/alkaline earth metal hydroxides)
Strong Acids and Strong Bases
completely dissociates/ionizes
pH=
-log[H3O+]
pOH=
-log[OH-]
[H3O+] represents
an acid
[OH-] represents
a base
pH+pOH=
14
equation for dissociation (weak acid)
Ka=([H3O+][A-])/[HA]
larger K value
stronger acid
pH from Ka method
chemical equation for ionization equilibrium
equilibrium constant expression
table for initial/change in/equilibrium conc (put in terms of x)
substitute equilibrium conc.s into constant expressions, solve for x
determine pH of strong acid and base
excess divided by reactant excess
determine pH of weak acid and strong base (weak acid in excess)
pH=pKa+log [A-]/[HA]
determine pH of weak acid and strong base (strong base in excess)
Molarity of base
determine pH of strong acid and weak base (weak base in excess)
HH equation
determine pH of strong acid and weak base (strong acid in excess)
Molarity of solution from excess hydronium ions
determine pH of strong acid and weak base (equimolar)
conjugate acid of base
determine pH of weak acid and base
will reach equilibrium
polyprotic acids
more than one acidic proton; easier to remove first proton
Binary Acids
H + 1 other element
factors of binary acids
H-A bond most important factor
bond polarity most important within a group
pKa goes down, acid goes up
electronegativity decreases; weaker bonds
oxyacids
H + O + other element
factors of oxyacids
electronegativity of nonmetal increases acidity
more Os, more acidic
electron density decreases, acidity increases
resonance structures increase, anion more stable
inductive effects
add more electronegative atoms, acid strength increases
increased electronegative atoms makes base weaker
carboxylic acid
contain COOH
factors of carboxylic acid
other O-C takes from O-H and increases polarity
conjugate base has resonance forms to stabalize anion
Nitrogenous Bases
contains N; usually properties of bases; in DNA and RNA
anions of strong acids
are neutral
anions of weak acids
are conjugate bases; produce OH- in H20
Ka>Kb for ion
anion acicdic
Kb>Ka for ion
anion basic
hydrolysis:
reaction with H2O to produce H+ or OH-
polyatomic cations
usually conjugate acid of weak base
transition and post-transition metal cations
are acidic
Group I and II metal cation w anion of strong acid:
neutral
t/pt metal cation of polyatomic cation with anion of strong acid:
acidic
t/pt cation or polyatomic cation with anion of weak acid:
greater Ka or Kb determines pH
titration
change ration of acid and conjugate base
equivalence point:
acid and conjugate base equimolar
each indicator
has own pH range for color change
buffers:
weak conjugate acid-base pair restricts drastic change in pH
optimal pH:
pH=pKa
Note
Flashcard