ForceEnergyEntropy
Free Energy
What is Force ?
F=ma
force mass accel.
What is Force ?
S F=ma“Sum of the forces on an object is (directions matter) is equal to the mass of that object multiplied by it’s acceleration”
What is Force ? S F=ma
“Sum of the forces on an object is (directions matter) is equal to the mass of that object multiplied by it’s acceleration”
Gravitational Fg=mg m
This is a special case. When one of the two objects is Earth
Gravitation
m1
Fg=Gm1m2
r2
m2
r
G = 6.67×10−11 N m2 kg−2
Electrostatic
q1
Fe=ke
q1q2
r2
q2
r
ke=9.0 x 109 Nm2/C2
q is the amount of charge on each object
Charge of an electrone = 1.6 * 10-19 C
C= Coulomb a unit of charge
SarahAshley
ChristianZack P.
CharlieJeremy
DominiqueCarly
TrevorKarsten
JessyZack J.
SamAhmet
John
CoreyAakashHunterCarson
ShaneNickMax
1 2 3
4 5 6
Nanocalc Teams
What is Energy?Capacity to do Work. … What
does this mean?
Energy
Stored (Potential) Chemical Nuclear
MagneticElectrostatic
Mass
EM Radiation Light X-raysmicrowaves
Motion (Kinetic)
Energetics of an Explosion
TNT
In what form is the energy?
Energetics of an Explosion
Bang!
In what form is the energy?
Potential Energy U (or E)
Potential Energy U (or E)
F
Force, Energyand Bonding
Force, Energyand Bonding
A
B
ShakyNano Property #2:
All things shake, wiggle, shiver and move all around at the nanoscale.
Brownian Motion
In both cases the fluorescent particles are 2 microns in diameter. The left picture shows particles moving in pure water; the right picture shows particles moving in a concentrated solution of DNA, a viscoelastic solution in other words. The movies are 4 seconds of data, total; you can see a slight jump in the movie when it loops around. http://www.deas.harvard.edu/projects/weitzlab/research/brownian.html
Basic ThermodynamicsZeroth Law: If two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other.
First Law: Energy in the universe is conserved (it is also conserved in a closed system).
Second Law : Entropy increases
What is Entropy ?
What is entropy ?
A count of the number of equivalent states of a system
Equivalent ?
States ??
What is Temperature anyway?
What is it a measure of ?
MOTION
In specific Scientific Terms: Temperature is a measure of the average kinetic energy of the particles in a system.
TEMPERATURE
Heat is nano-scopic motionVery, Very cold
Warm
Hot
Flow of Heat
Thermal EnergyEthermal=1/2 k * Temperature
k = Botzmann’s constant (1.38*10-23J/K)
Ethermal=1/2 kTAverage Energy of each degree of freedom in a system.
At room Temperature, Ethermal= 4*10-21 J
or 0.025 eV
Fahrenheit, Celsius, Kelvin
Kelvin
3000 100-200 -100-273 200
273 373173730 473 573
57232 212-328 -148-459 392
Celsius
Fahrenheit
Kinetic Energy
Ekinetic=1/2 (mass)*(velocity)2
Ekinetic= 1/2 mv2
We can set the thermal energy of an object equal to its kinetic energy to see how fast it is moving. This is appropriate for relatively “free” particles.
Ekinetic=Ethermal
1/2 mv2 = 1/2 kTv=(kT/m)1/2
Thermally induced Kinetic Energy
v=(kT/m)1/2 (appropriate for a free particle)
Person 100kg 6*10-12m/s
Grain of Sand 10 mg 7*10-8m/s (10nm/s)
10 micron bead 4*10-12kg 20 microns/s
1 micron bead 4*10-15kg 700 micron/s
Virus 5*10-19kg 9 cm/s
Oxygen Molec. 5*10-26kg 270 m/s
Thermal Vibrations:Carbon Nanotube
Entropy
Entropy
DS < 0
Entropy
Entropy
DS < 0
Entropy
Entropy
DS > 0
Bonding/Assembly
Bond Energy vs. Thermal Energy
Force, Energyand Bonding
Free EnergyEnthalpy and Entropy
Pot
enti
al E
nerg
y
xEb=bond energy
x
Transition State
Ub
0
Uactiv.
x
Bonding / Assembling
x
Disassociating
Pot
enti
al E
nerg
y
xUb
x
0
Bonding / Assembling
Pot
enti
al E
nerg
y
xUb
x
0
Disassociating
Effects of thermal energy on Bond StrengthP
oten
tial
Ene
rgy
xUb
kBT
Thermal Energy affects the Dissociation Constant and Bond Strength.
Thermal Energy aids the dissociation of a bond.
0
Bond Strength: Boltzman FactorWhat is the probability that a bond will spontaneously dissociate????
P=e-Ub/kTkT at room temperature = 0.025 meV
The rate of dissociation
rd = w e-Ub/kBT
Attempt frequencyVibrational frequency of bond orinverse relaxation time
Probability per attempt
Rate of dissociation
Force, Energyand Bonding
Force, Energyand Bonding
A
B
DU = UB –UA < 0Spontaneous & Stable
Gibbs Free Energy
G = - H TS
Thermodynamic Potential
Helmholtz Free Energy
F = U - TS
Temp EntropyEnthalpy
U + PV
Potential Energy (chemical typically)
Thermodynamic Potential
Helmholtz Free Energy
F = U - TSDF = DU - TDS
When change in free energy is negative, process is spontaneous
Define System
DF = DU – TDS
DU = ? > or < 0 ?DS = ? > or < 0 ?
When change in free energy is negative, process is spontaneous
Bond Strength: Boltzman FactorWhat is the probability that a bond will spontaneously dissociate????
P=e-Ub/kTkT at room temperature = 0.025 meV
The rate of dissociation
rd = w e-Ub/kBT
Attempt frequencyVibrational frequency of bond orinverse relaxation time
Probability per attempt
Rate of dissociation
DU > or < 0 ?DS > or < 0 ? DF = DU - TDS
DU > or < 0 ?DS > or < 0 ? DF = DU - TDS
AB
C
D
EWhich representative state of the fiber has highest entropy?
