Mastering Thermodynamics: Understanding Heat and Entropy

1. Thermodynamics Entropy

2. Heat and Entropy • In general, if the laws of nature are allowed to act without interference, a disorderly arrangement is more likely to result than an orderly one • Entropy is a measure of a system’s disorder • Systems with maximum disorder are favored • Once a system has reached a state of greatest disorder, it will tend to remain in that state and have maximum entropy

3. Heat and Entropy • Increasing disorder reduces the energy available for work • If all of the gas particles in an engine were moving toward the piston, more work would be done than due to random motion of the particles • Solids are more ordered than liquids; liquids are more ordered than gases • Local decreases entropy must be offset by increases elsewhere in the universe • Perform work on or add energy to the system

4. Heat and Entropy • The universe will eventually settle into a state of thermal equilibrium and reach maximum entropy • The transfer of heat and the ability to do work will be impossible • All physical, biological and chemical processes in the universe will stop • Known as the heat death of the universe • Projected to happen about 100 trillion years in the future