🔥 Thermodynamics & Energetics
91 chemistry topics in Thermodynamics & Energetics, from beginner to intermediate to advanced level. Each topic has a clear explanation, a worked example, frequently asked questions and an interactive lesson.
Beginner topics in Thermodynamics & Energetics (18)
- System and SurroundingsThe system is the part of the universe under study; everything else is the surroundings.
- Open Closed Isolated SystemsOpen systems exchange matter and energy, closed exchange only energy, isolated exchange…
- EnergyThe capacity to do work or transfer heat, measured in joules.
- HeatEnergy transferred due to a temperature difference.
- Exothermic ReactionsReactions releasing heat to the surroundings, with negative enthalpy change.
- Endothermic ReactionsReactions absorbing heat from the surroundings, with positive enthalpy change.
- Specific Heat CapacityHeat needed to raise one gram of a substance by one degree Celsius.
- Thermochemical EquationA balanced equation that includes the enthalpy change for the stated amounts.
- Thermal EquilibriumThe state in which no net heat flows between objects at the same temperature.
- Temperature ScalesCelsius, Fahrenheit and Kelvin scales; the absolute Kelvin scale is used in scientific…
- Fuel Calorific ValueThe heat released per gram or mole of fuel burned.
- Energy DensityThe amount of energy stored per unit mass or volume of a fuel.
- Fossil FuelsCoal, oil and natural gas formed from ancient organisms, burned for energy and releasing…
- Enthalpy Level DiagramA diagram showing reactant and product enthalpies and the sign of delta H.
- Standard ConditionsReference conditions of 1 bar pressure, 1 M concentration and usually 298 K for tabulated…
- Calorie vs JouleOne thermochemical calorie equals 4.184 joules.
- Heat of Fusion of IceAbout 334 joules per gram are needed to melt ice at 0 degrees Celsius.
- Heat of Vaporization of WaterAbout 2260 joules per gram are required to vaporize water at 100 degrees Celsius.
Intermediate topics in Thermodynamics & Energetics (38)
- State FunctionA property depending only on the current state, such as enthalpy, entropy and internal…
- Path FunctionA quantity such as heat or work that depends on the route taken between states.
- Work in ChemistryEnergy transferred by force over distance; pressure-volume work equals -P times change in…
- Internal EnergyThe total kinetic and potential energy of all particles in a system.
- First Law of ThermodynamicsEnergy is conserved: change in internal energy equals heat added plus work done on the…
- EnthalpyHeat content H equal to U plus PV; the change equals heat at constant pressure.
- Molar Heat CapacityHeat required to raise one mole of substance by one kelvin.
- CalorimetryMeasuring heat changes in a reaction using a calorimeter and q equals m c delta T.
- Bomb CalorimeterA constant-volume calorimeter used to measure heat of combustion.
- Coffee-Cup CalorimeterA constant-pressure calorimeter for measuring enthalpy changes in solution.
- Standard Enthalpy of FormationEnthalpy change when one mole of a compound forms from its elements in standard states.
- Standard StateThe most stable form of a substance at 1 bar, usually 298 K.
- Enthalpy of CombustionHeat released when one mole of a substance burns completely in oxygen.
- Enthalpy of NeutralizationHeat released when an acid and base form one mole of water, about -57 kJ for strong ones.
- Enthalpy of SolutionHeat change when one mole of solute dissolves in solvent.
- Hess's LawThe total enthalpy change of a reaction is the same however many steps it takes.
- Reaction Enthalpy from Formation DataDelta H equals the sum of product formation enthalpies minus the sum for reactants.
- Bond Enthalpy CalculationsEstimate reaction enthalpy as bonds broken minus bonds formed.
- Enthalpy of AtomizationEnergy needed to convert one mole of a substance into gaseous atoms.
- Spontaneous ProcessA change that occurs without continuous external input.
- EntropyA measure of disorder or the number of microstates available to a system.
- Second Law of ThermodynamicsIn any spontaneous process the total entropy of the universe increases.
- Standard Molar EntropyAbsolute entropy of one mole of substance under standard conditions.
- Entropy Changes in ReactionsEntropy generally rises with more gas moles, greater freedom of motion and dissolution.
- Entropy of Phase ChangeFusion and vaporization increase entropy, equal to enthalpy change divided by temperature.
- Gibbs Free EnergyG equals H minus TS; a negative change signals a spontaneous process at constant T and P.
- Gibbs Energy and SpontaneityReactions are spontaneous when delta G is below zero, depending on both enthalpy and…
- Standard Free Energy of FormationThe Gibbs energy change when one mole of compound forms from its elements in standard…
- Isothermal ProcessA change at constant temperature.
- Isobaric ProcessA change at constant pressure.
- Isochoric ProcessA change at constant volume where no pressure-volume work is done.
- Zeroth Law of ThermodynamicsIf two systems are each in thermal equilibrium with a third, they are in equilibrium with…
- Latent HeatHeat absorbed or released during a phase change at constant temperature.
- Hydrogen as FuelBurning hydrogen yields only water and has high energy per mass but storage challenges.
- BiofuelsRenewable fuels such as ethanol and biodiesel derived from biomass.
- Hess's Law Cycle DiagramEnthalpy cycles visualize alternative routes between reactants and products.
- Activation Energy ProfileA plot of energy against reaction progress highlighting the barrier and enthalpy change.
- Thermodynamics of DissolutionWhether a salt dissolves depends on enthalpy of solution and the entropy increase.
Advanced topics in Thermodynamics & Energetics (35)
- Born-Haber EnergeticsLattice energy is obtained by summing atomization, ionization, electron affinity and…
- Boltzmann Entropy FormulaS equals k times the natural log of W, the number of microstates.
- Third Law of ThermodynamicsThe entropy of a perfect crystal is zero at absolute zero.
- Temperature Dependence of SpontaneitySign combinations of delta H and delta S decide whether a reaction is spontaneous at high…
- Free Energy and EquilibriumDelta G standard equals minus RT ln K linking thermodynamics with equilibrium constants.
- Reaction Quotient and Free EnergyDelta G equals delta G standard plus RT ln Q gives direction under nonstandard conditions.
- Free Energy and WorkThe decrease in Gibbs energy equals the maximum non-expansion work obtainable.
- Helmholtz Free EnergyA = U minus TS, the work potential at constant temperature and volume.
- Coupled ReactionsA spontaneous reaction can drive a nonspontaneous one, as ATP hydrolysis powers…
- Reversible ProcessAn idealized process proceeding through equilibrium states, giving maximum work.
- Irreversible ProcessA real process proceeding at finite rate that generates entropy.
- Adiabatic ProcessA change with no heat exchange with surroundings.
- Cp and CvHeat capacities at constant pressure and volume differ by R for an ideal gas.
- Heat Capacity RatioGamma equals Cp over Cv and governs adiabatic gas behaviour.
- Carnot CycleAn ideal reversible heat engine cycle setting the maximum efficiency between two…
- Heat Engine EfficiencyMaximum efficiency equals 1 minus Tcold over Thot.
- Equipartition TheoremEach quadratic degree of freedom contributes one half kT to the average energy of a…
- Degrees of FreedomIndependent ways a molecule can store energy through translation, rotation and vibration.
- Statistical ThermodynamicsLinks microscopic particle behavior to macroscopic properties using probability.
- Partition FunctionA sum over energy states from which thermodynamic quantities can be derived.
- Boltzmann DistributionPopulations of energy states fall off exponentially with energy at a given temperature.
- Chemical PotentialThe change in Gibbs energy per mole of added component, controlling phase and reaction…
- Fugacity and ActivityEffective pressure and concentration that correct for non-ideal behaviour.
- Gibbs Phase RuleDegrees of freedom F equals components C minus phases P plus 2.
- Clapeyron EquationGives the slope of a phase boundary in terms of enthalpy and volume change.
- Thermodynamic vs Kinetic ControlThermodynamic products are the most stable; kinetic products form fastest.
- Entropy of MixingMixing substances increases entropy and drives spontaneous dissolution of ideal solutions.
- Entropy and the Arrow of TimeThe second law gives processes a preferred direction because entropy of the universe…
- Heat Death ConceptA hypothetical end state in which maximum entropy leaves no free energy gradients.
- ExergyThe maximum useful work obtainable from a system as it comes to equilibrium with…
- Joule ExperimentShowed that mechanical work and heat are equivalent, establishing the mechanical…
- Gibbs-Helmholtz EquationRelates the temperature dependence of free energy to enthalpy.
- Van't Hoff EquationGives how the equilibrium constant changes with temperature through the reaction enthalpy.
- Maxwell RelationsEqualities between partial derivatives of thermodynamic potentials derived from state…
- Residual EntropyNonzero entropy at 0 K in crystals with disordered orientations, as in carbon monoxide…
Frequently asked questions about Thermodynamics & Energetics
How many topics are in Thermodynamics & Energetics?
Thermodynamics & Energetics has 91 topics, from beginner to intermediate to advanced level.
Where should I start in Thermodynamics & Energetics?
Start with System and Surroundings at the beginner level, then work through the topics in order.
Does every topic have an explanation and an example?
Yes. Each topic page has an in-depth explanation, a worked example, FAQs and links to related topics.