Free Energy & Chemical Reactions

These flashcards cover key vocabulary and concepts related to free energy and chemical reactions, important for exam preparation.

Standard Conditions

The set of defined conditions for measuring the properties of substances, typically at 1 atm pressure and a temperature of 25°C.

Third Law of Thermodynamics

States that the entropy of a perfect crystal approaches zero as the temperature approaches absolute zero (0 K).

Standard Entropy Change (ΔS°)

The change in entropy for a reaction when all reactants and products are in their standard states.

Absolute Entropy

The total entropy of a substance, representing the dispersion of energy through its particles.

Molar Mass and Entropy

The larger the molar mass of a molecule, the higher its entropy due to increased energy dispersion.

Relative Standard Entropy

Refers to the comparison of entropy values among different states of matter, such as gas, liquid, and solid.

Free Energy of Formation (ΔGf°)

The change in free energy when 1 mol of a compound forms from its constituent elements in their standard states.

Calculating ΔG°

The process of determining the standard free energy change for a reaction at standard conditions.

Reversible Reactions

Reactions that can achieve a theoretical limit of free energy change, allowing them to go forward and reverse.

Irreversible Reactions

Reactions where some of the free energy is lost as heat, making them unable to return to the original state.

Dissolved Solids Entropy

Dissolved solids generally exhibit greater entropy due to the distribution of particles throughout a mixture.

Absolute Entropy Value

The absolute entropy of substances is always positive and is measured in J/mol·K.

Standard Free Energies of Reaction

Defined by the equation ΔG° = ΔH° - TΔS°, linking free energy, enthalpy, and entropy.

Entropic Effects in Reactions

In exothermic reactions, heat increases surroundings' entropy, reducing the energy available for work.

Energy Dispersal

The dispersal of energy through the states of a substance, affecting its entropy and physical properties.