Entropy and Thermodynamics Flashcards

Flashcards about Entropy and Thermodynamics

Thermodynamics

Study of energy and its transformations.

Kinetics

Deals with the speed of reactions.

Thermodynamics

Deals with the energy (E), enthalpy (H), entropy (S), and Gibbs free energy (G) of reactions

System

What we want to study

Surroundings

Everything else outside of what we want to study

First Law of Thermodynamics

The total energy of the universe is a constant; energy cannot be created or destroyed but can be transformed from one form to another.

Internal Energy (E)

Total energy of a system.

Heat (q) and Work (w)

Energy can be transferred via these two things.

Enthalpy (H)

Heat exchanged under constant pressure conditions

Endothermic Reaction

Reaction where the system gains heat from its surroundings.

Exothermic Reaction

Reaction where the system gives off heat to its surroundings.

Spontaneous Process

Process that occurs without outside intervention.

Nonspontaneous Process

Process that requires outside intervention to occur.

Entropy (S)

Thermodynamic function that increases with the number of energetically equivalent ways to arrange the components of a system to achieve the same state.

k

Boltzmann’s constant (1.38 x 10-23 J/K)

W

Number of energetically equivalents ways to arrange the components of a system (microstates)

Macrostate

Overall state of the system.

Microstate

Exact distribution at any one moment (like a snapshot).

Things that lead to greater entropy for a system

More disorder; S (gas) > S (liquid) > S (solid); dissolving a crystalline solid in solution; more moles of gas are produced; higher molar mass; greater molecular complexity.

Second Law of Thermodynamics

For any spontaneous process, the entropy of the universe increases

Standard State

Pure gas at a pressure of exactly 1 atm; pure substance in its most stable form at a pressure of 1 atm; substance in solution: concentration of exactly 1M.

Standard Changes

Change for a reaction where all reactants and products are in their standard states

Standard molar entropy

Measure of energy dispersed into one mole of a substance at 25°C

Third Law of Thermodynamics

The entropy of a perfect crystal at absolute zero (0 K) is zero.