Thermochemistry and Thermodynamics

Comprehensive vocabulary flashcards covering the concepts of energy, thermodynamic laws, mechanical energy, calorimetry, specific heat, Gibbs free energy, entropy, and enthalpy.

Energy

The capacity to do work or produce change.

Work ($W$)

The force applied to move an object over some distance, calculated as $W = F \times d$.

Joule ($J$)

The SI unit for work and energy, equivalent to $1\,N \cdot m$.

Calorie

The amount of energy (heat) required to raise the temperature of one gram of water by one degree Celsius, where $1\text{ calorie} = 4.184\,J$.

First Law of Thermodynamics (Conservation of Energy)

The principle stating that energy can neither be created nor destroyed, only changed in form under ordinary means; the energy in a closed system is constant.

Kinetic Energy

The energy of motion, consisting of translational, rotational, and vibrational types.

Potential Energy

Stored energy of position, categorized as relative (energy of position) or absolute (stored energy).

Elastic Collision

A collision in which there is no net change in energy.

Inelastic Collision

A collision in which energy is lost, such that the energy after the collision is less than the energy before the collision.

Calorimetry

The experimental measure of the heat flow for a chemical or physical process.

Calorimeter

A device used to measure heat flow.

Heat Equation ($Q$)

The formula used to calculate heat transferred: $Q = mc\Delta T$, where $m$ is mass, $c$ is specific heat, and $\Delta T = T_{\text{final}} - T_{\text{initial}}$.

Specific Heat

An intensive physical property representing the amount of energy required to raise the temperature of one gram of a substance by $1\,^\circ\text{C}$, measured in $\text{cal}/g\,^\circ\text{C}$ or $J/g\,^\circ\text{C}$.

Insulators

Materials characterized by having high specific heats.

Conductors

Materials characterized by having low specific heats.

Second Law of Thermodynamics

The principle stating that all change tends towards minimum energy and maximum entropy.

Gibbs Free Energy ($\Delta G$)

All of the energy available to do work, given by the relationship $\Delta G = \Delta H - T\Delta S$.

Spontaneous Reaction

A reaction characterized by a negative Gibbs free energy ($-\Delta G$), occurring when a continual supply of energy is not required.

Nonspontaneous Reaction

A reaction characterized by a positive Gibbs free energy ($+\Delta G$), occurring when a continuational supply of energy is required.

Equilibrium ($\Delta G = 0$)

The condition where the change in Gibbs free energy equals zero and the rate of the forward and reverse reactions is equal.

Entropy ($S$)

A measure of randomness or disorder named for Nicholas Sadi-Carnot, increasing across states of matter as $S_{(s)} < S_{(l)} < S_{(g)}$.

Enthalpy ($\Delta H$)

The heat content or energy stored in the bonds of a substance during its formation, calculated as $\Delta H = H_P - H_R$.

Exothermic Reaction

A process where $\Delta H$ is negative ($-\Delta H$) or heat is released ($-Q$), meaning the energy of the products is less than that of the reactants ($\text{Reactants} \rightarrow \text{Products} + \text{Energy}$).

Endothermic Reaction

A process where $\Delta H$ is positive ($+\Delta H$) or heat is absorbed ($+Q$), meaning the energy of the products is greater than that of the reactants ($\text{Reactants} + \text{Energy} \rightarrow \text{Products}$).