non-spontaneous is...
thermodynamically unfavorable
2nd law with entropy
volumes proportionality with entropy
as V goes up, so does S
as the more temperature, the more energy, the mor entropy
is H < 0 and S < 0
T=100k
spontaneous, low temperature, T delta S is small
delta S =
(sum of S products) - (sum of S reactants)
DO NOT FORGET TO ACCOUNT FOR THE MOLES IN THE REACTION!!!
2nd law of thermodynamics
oxidation half-reaction
x --> X+ + e-
if a reaction is thermodynamically favorable
delta G and the energy of the product is lower than that of the reactants
1. G = negative = k>1; G = positive = k
how a reaction that is thermodynamically unfavorable occur
a reaction can be coupled with a reaction that is favorable to push it forward
Examples:
- photosynthesis
- ATP
- Charging a battery with electricity
is H < 0 and S > 0
spontaneous at all Temps, delta G <0
oxidation happens, losing electrons
G, S, H
S = entropy
G = Gibbs free energy
H = heat energy
entropy
degrees of freedom of a molecule
if a reaction is kinetically favorable
it has k>1, relatively low activation energy
how K and G relate to each other
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!!
chemical energy is converted to electrical energy with spontaneous redox reaction
Voltage
consists of oxidizing agent in one compartment that pulls electrons through a wire from a reducing agent
how do you calculate Gibbs free energy
overall cell reaction
1 joule of work / coulomb of charge transferred
J/C = units
charging = non-spontaneous
using = spontaneous
1st law of thermodynamics
in an isolated system energy can neither be created or destroyed; only transferred or converted, meaning E lost = negative E gained
3rd law of thermodynamics
galvanic = anode is negative and cathode is positive
electrolytic = anode is positive and cathode is negative
is H > 0 and S > 0
T = 500k
spontaneous, high temperature, T delta S is large
what is Gibb's free energy
cathode
reduction happens, gaining electrons
products have less energy than reactants, spontaneous, graph will end lower than it started
voltage equation
