Thermodynamics Adapted By: Mr. Kling 

Laws of Thermodynamics The study of thermodynamics is about energy flow in natural systems The Laws of Thermodynamics describe what is known about energy transformations in our universe

First Law of Thermodynamics Law of conservation of energy “Energy is neither created nor destroyed but can be transformed from one form to another” Energy of the universe is constant

Transfer vs. transformation Transfer involves a change in location e.g. water falling as rain, running off the land into a river then to the sea Transformation involves a change in state e.g. evaporation of water from a lake into the atmosphere Energy examples

Second Law of Thermodynamics Entropy Law Entropy = disorder, randomness or chaos “In an isolated system, entropy tends to increase spontaneously” Every energy transformation or transfer results in an increase in the disorder of the universe

Second Law continued Most conversions are less than 100% efficient and therefore some energy is lost or wasted Usually this energy is lost in the form of HEAT (= random energy of molecular movement) e.g. only 25% of chemical energy stored in gasoline is transformed in to motion of the car 75% is lost as heat!! Without adding energy to a system, the system will break down e.g. a house

Energy vs. materials Within a system energy cannot be re-used BUT materials can be recycled over and over with little to no loss of utility Energy flows through systems while materials circulate around systems e.g. photosynthesis - E and carbon

Stock (or storage) Stock = stored energy or material Examples Water Carbon Energy

Equilibrium A state of balance among the components of a system Steady state equilibrium - despite fluctuations, average condition of the system remains unchanged over time

Equilibrium in natural systems In nature, most open systems are in steady state equilibrium Steady state equilibrium compared to static equilibrium…

Equilibrium Static equilibrium - no change in the system

Stability of an Equilibrium Stable equilibrium - system returns to the same equilibrium after disturbance

Stability of an Equilibrium Unstable equilibrium - system reaches a new equilibrium after disturbance

Feedback The return of part of the output of a system as input so as to affect subsequent outputs Responsible for maintenance of equilibria e.g. thermostat

Negative feedback Feedback that tends to neutralize or counteract any deviation from an equilibrium Self-regulation leading to steady state equilibrium Promotes stability e.g. sea otter and sea urchin populations

Positive feedback Feedback that amplifies or increases change and leads to a deviation from equilibrium ‘vicious cycle’ e.g. global warming and melting ice caps

Complexity and stability Most natural systems are very complex with energy and material flow and feedback loops The more complex a system, the more stable it is e.g. old growth forest versus replanted monoculture