video Flashcards
for G = -vFE,, what are the units for G
J/mol
also,, standard E gives u standard G
when E is positive,, what is favoured
product formation
when G is negative,, what is favoured
product formation
what K value is needed for products to be favoured
a large positive number
much greater than 1
negative E means
non spontaneous in forward direction
reactants are favoured
positive G means
not spontaneous forward reaction
reactants are favoured
what k value is needed for reactants to be favoured
K needs to be very very small
not negative tho!!
gibbs and rate constant
G = -RTln(k)
cell diagram,, what goes on the LHS of the salt bridge
the ‘anode’
the thing that is oxidised
start with solid, then aq
large Q number
lots of products
pro/rea to rea/pro
1/Q answer
how do we find ratio of pro and rea
use nernst equation but find Q
when balancing 2 equations do u multiply voltage
nope
u multiply everything esle so
when theres no solid,, only ions,, how do u write the cell notation
highest oxidation state, lower oxidation state | Pt(s)
we can use Pt bc its inert!!
in cell notations,, do we add the big numbers from balancing equations
nope!! dont add the big numbers girl 💗
how to balance
balance core element
then oxygens
then hydrogens
then charges
then to combine make sure e- cancel out <3
how to balance under basic conditions
do it in acidic ones,, then add X OH to match XH+ to both sides
which turns it into H2O
which u then cancel from both sides
then make sure the charges are equal!!
make sure u add OH- to both sides tho <3
what happens when u increase conc of a reactant
more products form
reaction becomes more spontaneous in the forward reaction
more positive Ecell,, CELL POTENTIAL GOES UP!!! more positive = larger number
what happens if u decrease the concentration of the reactants
backward reaction occurs to oppose the lower concentration.
backward reaction becomes spontaneous
Ecell gets more negative
forward reaction is less spontaneous
CELL POTENTIAL GOES DOWN,, less positive
smaller Ecell
increase product concentration
backward reaction is favoured
forward reaction is less spontaneous. backward reaction is spontaneous. reactants are favoured
Ecell gets smaller!!!
decrease product concentration
forward reaction is favoured as le chatliers principle explains how more products will be formed to oppose the lower conc. this means the forward reaction is favoured and more spontaneous
this makes Ecell larger!! due to larger Q, making E larger
how do u increase the cell potential
products need to be larger : nominator for Q.
aka formward dreaction must be favoured
aka decrease products
aka increase reactants
how do u decrease cell potential
reactants need to be larger (denominator)
aka increase product conc
aka lower reactant conc
when is Ecell greater than E*cell
low product conc
high rea conc
when is Ecell smaller than E*cell
increase pro conc
decrease rea conc
what is Q girl
reaction quotient
basically K ,, but not during equilibrium
conc of pro / conc of rea
POWER OF STOICHIOMETRY!!
only aq allowed ,, no solids
E cell =
cathode - (-anode)
cathode + correct anode
anode and its mass
loses it
X(s) -> 2e- + X(aq)
cathode and its mass
gains it
X(aq) + 2e- -> X(s)
in salt bridge,, anions flow towards the
anode
in salt bridge cations flow towards the
cathode
what does the salt bridge do
prevents the build up of charge
keeps the solutions equal
Zn2+ goes to cathode (cation) bc that side is gaining e- and getting more negative
SO4 2- goes to anode (anion) bc that side is losing e- and getting more positive
no salt bridge
equilibrium will occur
e- would start going back to anode
what is voltage
the potential difference between 2 points
current equation
current = charge / seconds
amp = 1c / second
c = coloumb of charge
C is
coloumb
charge
J is
energy
work
1 volt =
1J / 1C
i = Q / t
current (amps) = charge (coloumb) / second
when a battery has a positive cell potential,, Ecell,, what can occur
spontaneous reaction
meaning charge is created
work can be done to power things
aka light a light bulb etc
when Ecell = 0.00V,, the cell is dead,, u need a new bettery
what do we need to add to a cell notation
states and concentration and pressure!! pressure in atm
cell notation conc and pressure when not given
conc = 1M
pressure = 1atm
rate constant,, K,, at equilibrium
1
why do cations travel towards the cathode
attracted to the e- flowing to the cathode
Zn and Cu in
ZnSO4
CuSO4
Al and Co in
AlCl3
CoCl3 // CoCl2 depending on the ions (both 1M)
maximum amount of work that can be done =
DELTA G
can u multiply gibbs to get diff answers
yes
can u multiply Ecell to get diff answers
nope
