cell potential, Ecell, electromotive force (emf)
1 joule of work / coulomb of charge transferred
J/C = units
2nd law of thermodynamics
entropy of an isolated system is never decreasing, only if it is in a 2 or more system
3rd law of thermodynamics
if a reaction is thermodynamically favorable
G, S, H
S = entropy
G = Gibbs free energy
H = heat energy
exergonic reaction
products have less energy than reactants, spontaneous, graph will end lower than it started
how K and G relate to each other
G = negative = k>1
G = positive = k<1
k is close to 1, G is close to zero
k is far from 1, G is far from zero
volumes proportionality with entropy
(sum of S products) - (sum of S reactants)
DO NOT FORGET TO ACCOUNT FOR THE MOLES IN THE REACTION!!!
y + z --> Y+ + Z- (G<0)
is H < 0 and S < 0
as matter disperses, entropy increase, so, going from solid to liquid to gas would increase entropy, whilst going from gas to liquid to solid would decrease it
in an isolated system energy can neither be created or destroyed; only transferred or converted, meaning E lost = negative E gained
cathode
reduction happens, gaining electrons
if a reaction is kinetically favorable
galvanic cell
galvanic cell vs electrolytic cell
galvanic = anode is negative and cathode is positive
electrolytic = anode is positive and cathode is negative
entropy
degrees of freedom of a molecule
voltage equation
is H < 0 and S > 0
oxidation half-reaction
non-spontaneous is...
thermodynamically unfavorable
is H > 0 and S > 0
what is Gibb's free energy
the energy of a system related to changes in enthalpy and entropy, at a constant temperature.
basically implies that the system is at 1 atm and using 1 M solutions.
how do you calculate Gibbs free energy
how a reaction that is thermodynamically unfavorable occur
anode
oxidation happens, losing electrons
charging a battery vs using a battery
charging = non-spontaneous
using = spontaneous
Cell potential equation
Ecell = E (cathode) - E (anode)
IMPORTANT: if the reaction gets reversed (in order to balance, sometimes it will need to be reversed), the sign of the Ecell must switch, however if it gets multiplied (in order to balance) IT REMAINS THE SAME!!
