1. Laws of Thermodynamics
Sections 7.1 & 7.2

2. Learning Objectives… Define energy
Explain how energy is related to work and heat
Give examples of potential energy and kinetic energy
State the first and second law of thermodynamics
Discuss how the laws of thermodynamics relate to organisms

3. Energy
Energy = the capacity to cause change, the ability to rearrange matter
Work energy is measured in kilojoules (kJ)
Thermal energy (heat) is measured in kilocalories (kcal)
How we usually measure energy stored in food

4. 2 types of energy: Kinetic energy = energy of motion
Ex. A person walking
Heat = the kinetic energy of randomly moving particles
Is unable to do work
Potential energy = stored energy
Is due to location or structure
Ex. Chemical bonds in a molecule

6. Thermodynamics Thermodynamics = the study of energy
First Law of Thermodynamics = energy cannot be created or destroyed, but it can change forms
Known as “Conservation of Energy”
The total energy in a system plus its surroundings doesn’t change
Means organisms can NOT create energy
Must capture energy from the environment and transform it into a usable form

9. Second Law of Thermodynamics = when energy changes forms, some energy is converted to heat & disperses into the surroundings
No energy transfer is 100% efficient, some energy is always lost as heat!
As a result, the total amount of entropy in the universe continually increases

10. Entropy = a measure of the amount randomness or disorder in a system
Shown as the symbol “S”
Usable energy has low entropy
Heat has high entropy

12. Complex Life Forms & The 2nd Law of Thermodynamics
As organisms grow & develop they become more organized & complex
Is the 2nd law of thermodynamics wrong?
2nd law is still true because organisms can only maintain order with a constant input of energy
As they become more ordered the universe around them becomes more random
Happens because heat is released as organisms convert energy they obtain into a usable form