ENERGY AND THERMODYNAMICS

1
ENERGY AND THERMODYNAMICS
2
Thermodynamics

• Study of energy and its transformations

3
1st Law

• Energy cannot be created or destroyed
• Energy can change from one form to another

4
1st Law examples

• Photosynthesis
• Solar energy to chemical energy
• Deer eats a plant
• chemical energy to mechanical energy

5
Lets Review.

• Energy is the ability to do work
• Biological organisms need energy to grow, move,
  reproduce, etc.
• Energy can exist as stored energy or the energy
  of motion

6
Lets Review.

• Potential energy stored energy

7
Lets Review.

• Kinetic energy energy of motion

8
Different Forms of Energy

• Chemical energy stored in the chemical bonds of
  molecules

9
Different Forms of Energy

• Nuclear energy found within atomic nuclei

10
Different Forms of Energy

• Radiant (solar) energy transported from the sun
  as electromagnetic waves

11
Different Forms of Energy

• Heat thermal energy that travels from a hotter
  object to a colder one

12
Different Forms of Energy

• Mechanical energy in the movement of matter

13
So back to the 1st law

• The deer eats the plant. The plant has energy
  stored in molecules (chemical energy). The deer
  converts the chemical energy stored in the plant
  to mechanical energy (using the energy from
  eating the plant for moving around).

14
2nd law

• When energy is converted from one form to another
  some energy that is available to do work is
  degraded into a less usable form (as heat that is
  lost to the environment)

15
2nd law

• Total amount of energy is NOT decreasing (cannot
  be destroyed 1st law), however, energy
  available to do work is being degraded to less
  usable energy
• Less usable energy is more disorganized or random

16
2nd law

• Entropy measure of randomness
• Usable energy low entropy
• Heat high entropy

17
2nd law

• Entropy is continually increasing

18
Summary of 2nd law

• No process requiring an energy conversion is ever
  100 efficient because heat is always lost to the
  environment resulting in an increase in entropy.

19
Summary of 2nd law

• Examples
• Human cells are 50 efficient
• Auto engine chemical energy of gas to heat
  energy to mechanical energy 20-30 efficient

20
Flow of Energy Through Ecosystems

• Energy flow passage of energy in a one-way
  direction through the ecosystem

21
Flow of Energy

• Energy enters as radiant (solar) energy some of
  which is trapped by plants during photosynthesis

22
Flow of Energy

• Photosynthesis
• CO2 H2O radiant energy glucose (C6H12O6)
  H2O O2

23
Flow of Energy

• Energy is now in a chemical form stored in a
  molecule of glucose
• When the molecule glucose is broken down the
  chemical energy becomes available to do work,
  such as to grow

24
Flow of Energy

• Glucose molecules are broken down in a process
  called cell respiration
• Cell respiration releases the chemical energy
  stored in these molecules

25
Cell respiration

• C6H12O6 H2O O2
• CO2 H2O ENERGY

26
Flow of Energy

• Chemical energy stored in food molecules becomes
  available to do work (grow, movement,
  reproducing, etc.) also producing body heat which
  escapes into the environment, no longer a usable
  form of energy

27
Flow of Energy

• Energy CANNOT be recycled