Shortcut Methods

NEET Level:#

Shortcut Methods#

• Use the cyclic integral of entropy change, ∮ dS = Q/T, to calculate the change in entropy for a reversible process.
• Use the inequality ΔS ≥ Q/T to calculate the change in entropy for an irreversible process.
• Remember that the entropy of a pure crystalline substance at absolute zero is zero.
• Use the fact that the entropy of a system increases with increasing temperature and with increasing disorder to predict the direction of entropy changes.
• Use the T-S diagram to visualize the change in entropy for a given process.

Tricks

• Remember that ∮ dS = 0 for a cyclic process.
• Use the fact that Q/T is the area under the curve on a T-S diagram.
• Use the properties of entropy to simplify calculations.

CBSE Board Level:#

Shortcut Methods#

• Remember that the entropy of a system is a measure of its disorder.
• Remember that the entropy of a system increases when heat is added to it and decreases when heat is removed from it.
• Remember that the entropy of a pure crystalline substance at absolute zero is zero.
• Remember that the entropy of a system at a given temperature T is maximum when the system is in thermal equilibrium with its surroundings.
• Use the T-S diagram to visualize the change in entropy for a given process.

Tricks#

• Think about the disorder of a system to predict the direction of entropy changes.
• Use the properties of entropy to simplify calculations.