Three laws of thermodynamics
1) Conservation of energy (Energy can’t be created or destroyed).
2) For a spontaneous process, the entropy of the universe increases.
3) A perfect crystal at 0K has zero entropy.
w = -P V
Bond breaking is endothermic ( H>0)
Bond making is exothermic ( H<0)
G = Σn Gf,products - Σn Gf,reactants
ΔG = ΔH - TΔS
1) Elements in their elemental form are in the zero oxidation state.
2) Group 1 metals are +1 and Group 2 metals are +2.
3) Hydrogen is +1 except when bonded to metals (when it’s –1).
4) Transition elements must be determined by context (except Al=+3, Zn=+2, Cd=+2, Ag=+1)
5) The most electronegative elements get their typical oxidation state.
6) The last element not assigned balances the charge of the compound/ion.
Oxidizing Agent/ Reducing agent
The anode is always the site of oxidation
The cathode is always the site of reduction
c) Electrons always flow from anode to cathode
d) Anions flow to the anode and cations to the cathode through the salt bridge
e) In the galvanic/voltaic (spontaneous) cells, the cathode is + and the anode is – The signs are the opposite in electrolytic (non-spontaneous) cells.
f) For metal/metal salt solution cells, the cathode gains mass, while the anode loses mass.
G < 0 (-)
Ecell > 0 (+)
E= E° (.0592/n) log Q