Chemical Thermodynamics Flashcards

Flashcards for Chemistry Lecture Review

Thermodynamics

The study of the changes in energy and transfers of energy that accompany chemical and physical processes.

Energy

The capacity to do work.

Kinetic Energy

Energy of motion.

Potential Energy

Energy that a system possesses because of its position or composition.

Exothermic Reactions

Reactions that release energy in the form of heat.

Endothermic Reactions

Reactions that absorb energy.

First Law of Thermodynamics

The total amount of energy in the universe is constant; also known as the Law of Conservation of Energy.

System

The substances and the container involved in the chemical and physical changes.

Surroundings

The environment around the system.

Universe

The system plus the surroundings.

Thermodynamic state of a system

The set of conditions that specify all of the properties of the system.

State functions

Properties of a system that depend only on the state of the system.

Enthalpy change (ΔH)

The quantity of heat transferred into or out the system as it undergoes a chemical or physical change at constant pressure.

ΔHrxn

The heat of reaction.

Calorimetry

Experimental technique used to determine the energy change associated with a chemical or physical process.

Specific heat (s)

Amount of heat necessary to raise the temperature of 1 g of a substance by 1 °C.

Thermochemical equations

A balanced chemical reaction plus the ΔH value for the reaction.

Standard molar enthalpy of formation (ΔHfo)

The enthalpy for the reaction in which one mole of a substance is formed from its constituent elements.

Hess’s Law

The enthalpy change for a reaction is the same whether it occurs by one step or by any (hypothetical) series of steps.

Bond energy

The amount of energy required to break the bond and separate the atoms in the gas phase.

Internal energy, E

All of the energy contained within a substance.

Spontaneous changes

Changes happen without any outside influences.

Entropy, S

Measure of the disorder or randomness of a system.

Third Law of Thermodynamics

At 0 K is zero.

Standard Gibbs Free Energy of formation

The free energy change that results when one mole of the compound is formed from theirs elements in their standard state.