Gen Chem II: Exam 3 Flashcards
what happens at the eq. pt.?
moles of titrant equals moles of analyte
when the indicator changes color
end point
how are indicators chosen?
they must change color near the eq. pt. pH
pH indicators are —
organic acids and dyes
SB/SA the pH at the eq. pt. is —
7
SA/SB before the eq. pt., pH is determined by —
excess acid
SA/SB after the eq. pt., pH is determined by —
excess base
WA/SB half eq. pt.
mid point
the mid point is located where
in the buffer region
WA/SB — equals — at the mid-point
pH, pKa
WA/SB the pH at the equivalence point is — bc —
greater than 7, the reaction bt the conjugate base and water
WA/SB before the titration begins, pH is determined by —
the weak acid and Ka
WA/SB after the titration begins, but before the eq pt, you have a — and pH can be calculated by —
buffer, H-H equation
WA/SB at the eq pt, pH is determined by the —
conjugate base and Kb
WA/SB after the eq pt, pH is determined by —
excess added base
WB/SA the pH at the eq pt is — bc of —
less than 7, reaction bt conjugate acid and water
WB/SA before the titration begins, pH is determined by —
weak base and Kb
WB/SA after the titration begins, but before the eq pt, you have a — and pH can be calculated by —
buffer, H-H equation (must convert to pKa)
WB/SA at the eq pt, pH is determined by the —
conjugate acid and Ka
WB/SA after the eq pt, pH is determined by —
excess added acid
amino acids are —
polyprotic acids
an amino acids contains a — and a — in the same molecule
weak acid and weak base
how much of a salt can dissolve in a given amount of solvent at a given temp
solubility
units of molar solubility
M
for a slightly soluble ionic compound in water, equilibrium bt a – and —
solute and aqueous ions
what happens when a common ion is added to an “insoluble” compound?
the equilibrium shifts to the left and the solubility decreases and a precipitate forms
the additions of H3O+ will — the solubility of a salt that contains the anion of a weak acid (basic anions); the equilibrium will shift tot he —
increase, right
when no more solid can dissolve
saturated
when Q=K
the solution is saturated and no change will occur
when Q > K
precipitate will form until the remaining solution is saturated
when Q
precipitate will not form bc the solution is unsaturated
used to separate a solution containing a mixture of ions
selective precipitation
added to the solution until the Q of the more soluble compound is almost equal to its K
precipitating ion
the — soluble compound precipitates to max amt
less
the — soluble compound remains in solution
more
need lone pair, NH3 is an example
ligand
consist of a central metal ion (lewis acid) covalently bonded to 2 or more anions or molecules, called ligands
complex ion
why are complex ions favorable?
enhances solubility of “insoluble” compounds
complex ion formation is a
stepwise process (Kf= Kf1 x Kf2 x Kf3 x Kf4)
reducing agent is —
oxidized
when the oxidation number increases
oxidation
when the oxidation number decreases
reduction
oxidizing agent is —
reduced
uses a spontaneous redox reaction to generate electrical energy
voltaic or galvanic cell
uses electrical energy to drive a nonspontaneous reaction
electrolytic cell
electrochemical cells
voltaic and electrolytic
both electrochemical cells consist of –
two electrodes placed in an electrolytic solution
the difference in electrical potential bt the anode and cathode is called: (3)
cell voltage, electromotive force, cell potential
— will always lose mass
anode
— will always gain mass
cathode
the voltage associated with a reduction reaction at an electrode when all solutes are 1 M and all gases are at 1 atm
standard reduction potential (E)
all half-cell potentials are measured relative to —
SHE- standard hydrogen electrode
Ecell for spontaneous reactions
positive
each half-reaction contains a — and a —
reducing agent and a oxidizing agent
the — oxidizing and reducing agents react to spontaneously form the — ones
stronger, weaker
a spontaneous redox reaction will occur between a — and —
oxidizing agent and any reducing agent that lies below it in the emf series
known concentration
titrant
unknown concentration
analyte
k>1 favors —
products
k
reactants
extensive
favors products
non extensive
favors reactants
battery
voltaic cell
recharger
electrolytic cell
cations move to —
cathode
anions move to —
anode
Formation constant (complex ion formation)
Kf
Formation constant
If
Kf=
[products]/[reactants]
