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Entropy

Definition

Entropy refers to the measure of disorder or randomness in a system. In chemistry, higher entropy means higher disorder and less predictability.

Related terms

Second Law of Thermodynamics: This law states that the total entropy of an isolated system can never decrease over time, meaning systems naturally progress towards a state of maximum entropy.

Gibbs Free Energy: A thermodynamic potential that measures the "usefulness" or process-initiating work obtainable from a system at constant temperature and pressure. It combines enthalpy and entropy into one value.

Microstates: In statistical mechanics, microstates refer to specific detailed configurations of a macroscopic system that may occur with a certain probability when defined by macroscopic variables such as energy, volume, or number of particles. The concept is closely linked to understanding entropy.

"Entropy" appears in:

Subjects (3)

  • AP Environmental Science

  • AP Physics 2

  • AP Psychology

Study guides (4)

  • AP Chemistry - 7.14 Free Energy of Dissolution

  • AP Chemistry - 9.1 Introduction to Entropy

  • AP Chemistry - 9.2 Absolute Entropy and Entropy Change

  • AP Chemistry - 9.9 Cell Potential Under Nonstandard Conditions

Practice Questions (20+)

  • Consider a reaction X + Y ⇌ XY. How can the entropy change from the particles be described?

  • Consider a reaction XYZ ⇌ X + Y + Z. How can the entropy change from the particles be described?

  • What happens to entropy as the temperature of a reaction increases?

  • What is the entropy difference between 1 mol of hydrogen gas (H₂) and 1 mol of oxygen (O₂) at the same conditions?

  • What changes would NOT increase entropy in a system?

  • In which of the following reactions is entropy increasing?

  • What tenet of the kinetic molecular theory (KMT) supports the positive correlation between entropy and temperature in ideal gases?

  • What law states that the entropy of the universe increases in a spontaneous reaction?

  • Which of the following would decrease the entropy of a system?

  • Which gaseous molecules would have the largest entropy at 25°C and 1 atm?

  • What temperature can zero entropy be achieved?

  • Which reaction has the most positive entropy change under standard conditions?

  • At a constant temperature, which of the following would increase entropy?

  • Which of the following describes the relationship between volume and entropy?

  • What is the general relationship between temperature and entropy for diatomic gases?

  • In which of the following reactions is entropy increasing?

  • True or false! Entropy can be measured BOTH absolutely and as a change.

  • Which of the following statements is true about the entropy change of a system that absorbs heat from its surroundings?

  • Which of the following statements is true about the relationship between entropy and kinetic control in a reaction?

  • Which of the following statements is true about the relationship between entropy and enthalpy in a reaction?

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About Us

About Fiveable

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CCPA Privacy Policy

Resources

Cram Mode

AP Score Calculators

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Glossary

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© 2024 Fiveable Inc. All rights reserved.

AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.