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Force Energy Entropy Free Energy

Force Energy Entropy Free Energy. What is Force ?. F = m a. accel. force. mass. What is Force ?. S F = m a. “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 ?.

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Force Energy Entropy Free Energy

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  1. Force Energy Entropy Free Energy

  2. What is Force ? F=ma accel. force mass

  3. 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”

  4. What is Force ? “Sum of the forces on an object is (directions matter) is equal to the mass of that object multiplied by it’s acceleration” S F=ma

  5. Fg=mg Gravitational m This is a special case. When one of the two objects is Earth

  6. m1m2 Fg=G Gravitation r2 G = 6.67×10−11 N m2 kg−2 m2 m1 r

  7. q1q2 q is the amount of charge on each object Fe=ke Electrostatic r2 Charge of an electron e = 1.6 * 10-19 C C= Coulomb a unit of charge ke=9.0 x 109 Nm2/C2 q2 q1 r

  8. Nanocalc Teams 1 2 3 4 5 6

  9. What is Energy? Capacity to do Work. … What does this mean? EM Radiation Light X-rays microwaves Energy Stored (Potential) Chemical Nuclear Magnetic Electrostatic Mass Motion (Kinetic)

  10. Energetics of an Explosion TNT In what form is the energy?

  11. Energetics of an Explosion Bang! In what form is the energy?

  12. Potential Energy U (or E)

  13. Potential Energy U (or E) F

  14. Force, Energyand Bonding

  15. Force, Energyand Bonding A B

  16. ShakyNano Property #2: All things shake, wiggle, shiver and move all around at the nanoscale.

  17. 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

  18. Basic Thermodynamics Zeroth 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

  19. What is Entropy ?

  20. What is entropy ? A count of the number of equivalent states of a system Equivalent ? States ??

  21. TEMPERATURE 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.

  22. Heat is nano-scopic motion Very, Very cold Warm Hot

  23. Flow of Heat

  24. Thermal Energy Ethermal=1/2 k * Temperature k = Botzmann’s constant (1.38*10-23J/K) Ethermal=1/2 kT Average Energy of each degree of freedom in a system. At room Temperature, Ethermal= 4*10-21 J or 0.025 eV

  25. Fahrenheit, Celsius, Kelvin Kelvin 0 73 173 273 373 473 573 100 Celsius 0 -200 200 -100 300 -273 Fahrenheit -459 -328 -148 32 212 392 572

  26. 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 kT v=(kT/m)1/2

  27. 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*10-26kg270 m/s

  28. Thermal Vibrations:Carbon Nanotube

  29. Entropy

  30. Entropy DS < 0

  31. Entropy

  32. Entropy DS < 0

  33. Entropy

  34. Entropy DS > 0

  35. Bonding/Assembly Bond Energy vs. Thermal Energy

  36. Force, Energyand Bonding

  37. Free EnergyEnthalpy and Entropy

  38. x Potential Energy Transition State Uactiv. 0 x Ub Eb=bond energy

  39. Bonding / Assembling x

  40. Disassociating x

  41. Bonding / Assembling x Potential Energy 0 x Ub

  42. Disassociating x Potential Energy 0 x Ub

  43. Effects of thermal energy on Bond Strength Thermal Energy affects the Dissociation Constant and Bond Strength. Thermal Energy aids the dissociation of a bond. Potential Energy 0 x Ub kBT

  44. Bond Strength: Boltzman Factor What is the probability that a bond will spontaneously dissociate???? kT at room temperature = 0.025 meV P=e-Ub/kT The rate of dissociation rd = we-Ub/kBT Rate of dissociation Attempt frequency Vibrational frequency of bond or inverse relaxation time Probability per attempt

  45. Force, Energyand Bonding

  46. Force, Energyand Bonding A B DU = UB –UA < 0 Spontaneous & Stable

  47. Thermodynamic Potential Gibbs Free Energy G = H - TS Enthalpy U + PV Temp Entropy Helmholtz Free Energy F = U - TS Potential Energy (chemical typically)

  48. Thermodynamic Potential Helmholtz Free Energy F = U- TS DF=DU- TDS Define System When change in free energy is negative, process is spontaneous

  49. DF=DU– TDS DU = ? > or < 0 ? DS = ? > or < 0 ? When change in free energy is negative, process is spontaneous

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