Unit Test 4: Ch15 (titration curves), Ch18, & Organic Chem Flashcards
(21 cards)
Buffer solution?
Buffer capacity?
Explain how a buffer solution of CH3COOH & CH3COO- would resist changes in pH
how to apply henderson hasselbach equation?
composed of a weak acid and conjugate base. Resists changes in pH
Amount of acid or base the buffer can neutralize before pH begins to change significantly
CH3COOH + OH- -> CH3COO- + H2O; CH3COO- + H+ -> CH3COOH
used to calculate pH of a buffer solution.
pH of a buffer is determined by ratio or magnitude of conjugate acid and base?
what about buffer capacity?
ratio
magnitude
to choose a weak acid for a buffer solution, pKa should be as close as possible to
desired pH
when calculating concentration of an acid or conjugate base in solution, you divide the mmol of acid/base by
total mmol of solution (acid + base)
Strong Acid + Strong Base Titration Curve:
- initial pH determined by?
-between initial and EQ point: as base is added, pH does what? pH is determined by?
-at EQ point, pH is ____.
- acid concentration = [H+]
- increases slowly then faster near EQ. strong acid concentration
-7
Weak Acid Titrated by Strong Base:
-Initial pH determined by?
-how to calculate pH between initial and EQ points?
-to calculate pH halfway to EQ point?
-at eq point, pH is always? why?
-after EQ, pH is determined by?
- concentration of acid, use ICE table
- write rxns and calcualte mmol changes/new concentrations. Use ice table.
- pH = pKa! :D
->7, there is no acid and only weak conjugate base in solution! - excess base!
Titration of Weak base w/ strong acid
-intial pH?
-between initial and EQ?
-at EQ? pH is always?
-after EQ?
-determined by weak base concentration. Use ice table
- mix of weak base and conjugate acid. use stoichiometry to calculate concentrations & calc new pH!
-weak conjugate acid is all that is present. <7.
-determined by excess H+
in a voltaic/galvanic cell ___ energy is converted to ____ energy
chemical, electrical
cathode vs. anode?
RED CAT, AN OX
Reduction occurs at cathode, anode has oxidation!
this is consistent between cell types!
purpose of salt bridge/porous disk?
how does a salt bridge work?
to maintain charges in solution, or else electrons wont be supplied.
contains a solution of aqueous salt ions, anions flow to anode, cations flow to cathode!
Standard conditions for a cell?
1M concentrations, 1atm for gases, and 25*C
E*cell is a measure of
calculated by
standard cell voltage
Ecell = Ecathode - E*anode
where these are the standard half-rxn-reduction-rxns (anode’s sign is not reversed)
the more ___ the potential, the more thermodynamically favorable a reduction rxn is
positive
describe line notation
Anode is listed on left
cathode is listed on right
Single verticle line separates phase differences
Double line separates salt bridge/porous disk
electrodes are on the outermost part of the line notation
ΔG* = -nFE*
what does this equation relate? through what variables?
change in free energy of the system in relation to moles of electrons transferred per mole rxn, Faraday’s constant, and standard cell potential!
Describe relationship between Ecell, E* cell, and concentrations in voltaic cells
Under standard conditions, Q = 1!
if we change concentrations, Q will change
if Q goes down, rxn will run more forward to reach K
K is very very large since rxn is spontaneous
So Ecell > E*cell whenever Q < 1
the opposite applies when Q>1, rxn slows down since it is closer to K
E*cell > Ecell
Electrolytic cells use supplied voltages to drive ____ reactions
thermodynamically unfavorable
in electrolytic cells, cathode’s sign is __ and anode’s is ___
this is the opposite/same as voltaic cells?
where does oxidation and reduction occur?
-, +
opposite!
same as always, RED CAT AN OX!!!!
what is plating?
current (I) = ?
we can use this to calculate what?
depositing neutral metal on electrode by reducing ions.
Δq/Δt….
mass changes!
Δq = I* Δt;
from Δq you can calculate mole e- using faraday’s constanst
then mole rxn
then mole of product!!!!!!!!!!!!!!!!!!!!
oxidizing agent?
reducing agent?
oxidizes something else, so the agent itself is reduced/accepts electrons readily.
reduces something else, so the agent itself is oxidized/donates electrons readily.
Know how to name alkanes/clycloalkanes
know how to name alkenes/cycloalkenes
know how to name alkynes
packets in notebook!
just practice these
