Entropy

Question 1

Define entropy

Answer 1

Measure of disorder in a system

Question 2

Describe the principle of entropy increase

Answer 2

Heat transfer from hot to cold reservoir => entropy of hot reservoir decreases (Q negative), entropy of cold reservoir increases (Q positive)

Question 3

Define the second law of thermo

Answer 3

total net entropy (surroundings and system) must be greater than or equal to zero for adiabatic processes

Question 4

Describe the principle of minimum energy/maximum entropy

Answer 4

• max entropy = closed system with constant internal energy

minimised total energy = closed system with fixed entropy

Question 5

Describe the effects of temperature and pressure on entropy

Answer 5

• Temp increased, molecule motion faster, more disorder -> delta S = positive
• Pressure increased, molecules closer to each other, less disorder -> delta S= negative

Question 6

Determine the free energy functions

Answer 6

• A= U- TS, A is helmholtz free energy —-> constant temp and volume, dA=0
• G= H-TS, G is gibbs free energy —-> constant temp and pressure, dG=0