Thermochemistry: Chemical Reactions and Energy

The ability to do work. It is defined as force multiplied by distance.

Energy stored within the chemical bonds of a substance.

The study of heat changes in chemical reactions.

The total internal energy of a system. It accounts for the sum of all kinetic and potential energies within the system.

A measure of the heat content of a substance at constant pressure.

The change in enthalpy that occurs during a chemical reaction.

A reaction that releases heat energy to the surroundings, leading to a decrease in the enthalpy of the system, making ∆H negative.

A reaction that absorbs heat energy from the surroundings, increasing the enthalpy of the system, making ∆H positive.

The change in enthalpy that accompanies the formation of one mole of a compound from its elements in their standard states.

The change in enthalpy that occurs when one mole of a substance undergoes complete combustion under standard conditions.

A technique used to measure the heat absorbed or released during a chemical reaction.

A law stating that the total enthalpy change of a reaction is independent of the pathway taken, only depending on the initial and final states.

The average energy required to break one mole of a specific type of bond in a gaseous state.

A measure of the disorder or randomness of a system. It's a measure of the number of possible arrangements of the components of the system.

The change in entropy of a system. It's the difference in entropy between the final and initial states.

A thermodynamic quantity that combines enthalpy and entropy changes to determine the spontaneity of a process.

A reaction that releases free energy and can occur spontaneously without external energy input.

A reaction that requires energy input to occur, making Gibbs free energy positive.

The state where the rates of the forward and reverse reactions are equal, resulting in no net change in the concentrations of reactants and products.

A principle that states that entropy always increases in a spontaneous process. This means that the total entropy of an isolated system can never decrease over time.

A principle that states that the entropy of a perfect crystal at absolute zero is zero. It sets a minimum value for entropy and provides a reference point for calculating entropy.

A process that occurs spontaneously in a given set of conditions.

A reaction that releases heat energy to the surroundings, resulting in a negative enthalpy change.

A reaction that absorbs heat energy from the surroundings, resulting in a positive enthalpy change.

A reaction that increases the entropy of the system, leading to a positive entropy change.

A reaction that decreases the entropy of the system, leading to a negative entropy change.

A reaction that is spontaneous at all temperatures, as both the enthalpy change and entropy change are favorable.

A reaction that may be spontaneous at higher temperatures but not at lower temperatures, as the entropy change favors spontaneity but the enthalpy change opposes it.

A reaction that is not spontaneous under normal conditions, as both the enthalpy change and entropy change oppose spontaneity.

A reaction that may be nonspontaneous at higher temperatures but spontaneous at lower temperatures, as the enthalpy change favors spontaneity but the entropy change opposes it.