Laws of Thermodynamics Flashcards
(23 cards)
What do the laws of thermodynamics describe?
The fundamental principles governing energy, heat, and work.
What does the Zeroth Law of Thermodynamics state?
If two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other.
What fundamental property does the Zeroth Law define?
Temperature.
Provide an example illustrating the Zeroth Law.
If a cup of tea and a spoon are both in thermal equilibrium with the air, they are in equilibrium with each other.
What is the First Law of Thermodynamics?
Energy cannot be created or destroyed, only transferred or converted from one form to another.
What is the mathematical expression for the First Law of Thermodynamics?
ΔU = Q - W
What do the variables in the First Law equation represent?
- ΔU: Change in internal energy of a system
- Q: Heat added to the system
- W: Work done by the system
What does the First Law imply about isolated systems?
The total energy of an isolated system remains constant.
Give an example of the First Law in action.
When gas is compressed in a piston, work is done on the gas, increasing its internal energy.
What does the Second Law of Thermodynamics state?
The total entropy of an isolated system always increases over time.
What is the mathematical form of the Second Law of Thermodynamics?
ΔS ≥ 0
What are two implications of the Second Law?
- Heat flows from hot to cold spontaneously.
- Energy conversions are never 100% efficient; some energy is always lost as heat.
Provide an example illustrating the Second Law.
A hot coffee cup cools down, increasing the entropy of the surroundings.
What does the Third Law of Thermodynamics state?
The entropy of a perfect crystal at absolute zero (0 K) is exactly zero.
What is the implication of the Third Law regarding absolute zero?
Absolute zero is physically impossible to reach, as it would require removing all energy from a system.
Provide an example related to the Third Law.
Even in deep space (~2.7 K), absolute zero is never achieved.
How does the First Law apply in engineering?
Design of heat engines and refrigerators.
What role does the Second Law play in cosmology?
Understanding entropy and the fate of the universe.
How is thermodynamics relevant in biology?
Thermodynamics in metabolism and energy transfer in cells.
Summarize the Zeroth Law.
Defines temperature and thermal equilibrium.
Summarize the First Law.
Energy conservation (ΔU = Q - W).
Summarize the Second Law.
Entropy always increases, and energy transformations are inefficient.
Summarize the Third Law.
Absolute zero is unreachable, and entropy approaches zero in a perfect crystal at 0 K.
