Water of Hydration
Hydration - to be surrounded by H2O
A polar molecule is hydrated by the partial charge interaction of the water molecule
Multiple H bonds increase solubility
Van der Waals Attraction
Non-specific attractions 3-4 in distance
CHM 4900 Thermodynamics
Allows a prediction as to the spontaneous nature of a chemical reaction:
Will this reaction proceed in a forward direction as the reaction is written:
Will A react with B to form C or not?
Is this reaction g
A cage of water molecules surrounding the non-polar molecule
This cage has more structure than the surrounding bulk media.
G = H -TS
Entropy decreases! Not favorable! Nature needs to be more disorganized. A driving force.
The f = for formation.
By convention, the free energy of the elements is taken as zero at 25 oC
The free energies of any compound can be measured as a sum of components from the free
energies of formation.
Standard State for Biochemistry
STP = Standard Temperature and Pressure and at 1M concentration.
We calculate DGs under these conditions.
aA + bB
cC + dD
We can calculate a G for each component
Combining (1) and (2)
Now if we are at equilibrium or DG = 0
Entropy (S) measure the degree of randomness
S = kbLnW
Each molecule has an inherent amount of energy which drives it to the most probable state or
kb or Boltzmans constant equates the arrangement probability to calories (joules
CHM 4900 Enthalpy
At constant pressure w = P V + w1
w1 = work from all means other than pressure-volume work.
PDV is also a state function.
By removing* this type of energy from U, we get enthalpy or to warm in
*remember the signs and directi
Physical properties of ice and water are a result of intermolecular hydrogen bonding
Heat of sublimation at 0 oC is 46 kJ/mol yet only 6 kJ/mol is gaseous kinetic energy and the heat
of fusion of ice is 6 kJ/mol which is only 15% o
Chemical Evolution - Life developed from carbon-based self replicating RNA molecules
RNA World Catalytic RNA
Chemical Evolution from HCN, NH3, H2O give rise to adenine or carbohydrates
By sparking CH4, NH3, H2O and H2 these are formed:
Molecules in life processes
C, H, O, N, P, and S all readily form covalent bonds.
Only 35 naturally occurring elements are found in life processes.
Earths Crust 47%
O2, 28% Si, 7.9%
Al, 4.5% Fe
B, C, N, Si and P can form three or more bo