Thermodynamic Laws

Question 1

State the Zeroth Law of Thermodynamics.

Answer 1

If two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other.

Question 2

What does the First Law of Thermodynamics state?

Answer 2

ΔU = Q − W

Energy is conserved in all processes.

Question 3

What is the perpetual motion machine of the first kind (PMM1)?

Answer 3

A hypothetical machine that violates the First Law by creating energy.

Question 4

What does the Second Law of Thermodynamics state?

Answer 4

The state of entropy of the entire universe, as an isolated system, will always increase over time, and changes in entropy can never be negative.

Question 5

What does the Third Law of Thermodynamics state?

Answer 5

At absolute zero, the entropy of a perfect crystal approaches zero.

Question 6

What is entropy?

Answer 6

ΔS= ∫ δQ/T

Entropy measures the disorder or randomness of a system.

Question 7

How is entropy production calculated for irreversible processes?

Answer 7

ΔS_universe = ΔS_system + ΔS_surroundings
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For irreversible processes,
ΔS_universe > 0