Free Energy and Entropy

Flashcards covering key vocabulary, concepts, and equations related to free energy and entropy.

Entropy Change Equation

ext{Δ}S_{sys} = rac{q_{rev}}{T}, where q_{rev} is the heat exchanged and T is the temperature in Kelvin.

Melting of Ice

The process of melting one mole of ice requires 6.02 kJ/mol, which is equivalent to 6020 J.

Entropy Change in Surroundings

When entropy change in the system is negative, the surroundings must have a positive and significant entropy change for the process to be spontaneous.

Total Entropy Change Equation

ext{Δ}S_{univ} = ext{Δ}S_{sys} + ext{Δ}S_{surr}.

Exothermic Processes

An exothermic process increases the entropy of the surroundings by adding heat.

Endothermic Processes

An endothermic process decreases the entropy of the surroundings by removing heat.

Temperature Impact on Entropy

Entropy change in the surroundings is more significant when the original temperature is lower.

Spontaneity Condition

A process is spontaneous if ext{Δ}G < 0. This occurs when ext{Δ}H is negative and ext{Δ}S is positive.

Gibbs Free Energy Equation

ext{Δ}G_{sys} = ext{Δ}H_{sys} - T ext{Δ}S_{sys}.

Equilibrium Condition

When ext{Δ}G = 0, the reaction is at equilibrium.

Second Law of Thermodynamics

The total entropy change, ext{Δ}S_{univ}, must be greater than zero for a spontaneous process.

Biological Systems Exception

Biological systems can decrease their own entropy by increasing the entropy of their surroundings.

Heat Exchange and Entropy Change

The entropy change ext{Δ}S_{surr} is inversely proportional to the temperature at which heat is gained or lost.

Calculating Entropy Change

The entropy change in the surroundings for a reaction is given by ext{Δ}S_{surr} = -rac{ ext{Δ}H_{rxn}}{T}.

Sign of Entropy Change in System

Increase in moles of products compared to reactants indicates a positive entropy change.

Concept of Gibbs Free Energy

Gibbs free energy indicates the maximum amount of work a system can perform at constant temperature and pressure.

Entropy Increase for Water Freezing

Water freezes spontaneously below 0°C because heat released increases entropy of surroundings.

Temperature Equilibrium

The temperature at which two phases, such as graphite and diamond, are in equilibrium is where ext{Δ}G_{rxn} = 0.