Search results for “Enthalpy”

Enthalpy Thermochemistry & Thermodynamics kJ/mol A thermodynamic state function equal to internal energy plus the product of pressure and volume. H = U + pV

Enthalpy Level Diagram Thermochemistry & Thermodynamics kJ/mol A diagram plotting the enthalpies of reactants and products to show the direction and size of the enthalpy change.

Enthalpy of Atomisation Thermochemistry & Thermodynamics kJ/mol The enthalpy change when one mole of gaseous atoms is produced from an element in its standard state. ΔH_at°

Enthalpy of Dilution Thermochemistry & Thermodynamics kJ/mol The enthalpy change when a solution is diluted from one concentration to another by adding solvent. ΔH_dil

Enthalpy of Fusion Thermochemistry & Thermodynamics kJ/mol The enthalpy change when one mole of a solid melts to a liquid at its melting point. ΔH_fus

Enthalpy of Neutralisation Thermochemistry & Thermodynamics kJ/mol The enthalpy change when an acid and a base react to form one mole of water under standard conditions. H⁺ + OH⁻ → H₂O, ΔH = −57.1 kJ

Enthalpy of Reaction Thermochemistry & Thermodynamics kJ/mol The heat absorbed or released when a reaction occurs at constant pressure in the molar amounts of the balanced equation. ΔH_rxn = ΣΔH_f(products) − ΣΔH_f(reactants)

Enthalpy of Solution Solutions & Colligative Properties kJ/mol The heat absorbed or released when one mole of a substance dissolves completely in a large excess of solvent. ΔH_sol = ΔH_lattice + ΔH_hyd

Enthalpy of Sublimation Thermochemistry & Thermodynamics kJ/mol The enthalpy change when one mole of a solid converts directly into vapour. ΔH_sub = ΔH_fus + ΔH_vap

Enthalpy of Vaporisation Thermochemistry & Thermodynamics kJ/mol The enthalpy change when one mole of a liquid becomes vapour at its boiling point. ΔH_vap

Bond Dissociation Enthalpy Thermochemistry & Thermodynamics kJ/mol The enthalpy change when one mole of a specific bond is broken homolytically in the gas phase. A–B(g) → A·(g) + B·(g)

Standard Enthalpy of Combustion Thermochemistry & Thermodynamics kJ/mol The enthalpy change when one mole of a substance burns completely in excess oxygen under standard conditions. ΔH_c°

Standard Enthalpy of Formation Thermochemistry & Thermodynamics kJ/mol The enthalpy change when one mole of a compound forms from its elements in their standard states. ΔH_f°

Endothermic Reaction Stoichiometry & Chemical Reactions kJ/mol A reaction that absorbs energy from the surroundings, giving a positive enthalpy change. ΔH > 0

Exothermic Reaction Stoichiometry & Chemical Reactions kJ/mol A reaction that releases energy to the surroundings, giving a negative enthalpy change. ΔH < 0

Hess's Law Thermochemistry & Thermodynamics kJ/mol The total enthalpy change of a reaction is the same regardless of the route taken, provided the initial and final states are identical. ΔH_total = ΣΔH_steps

Kirchhoff's Law Thermochemistry & Thermodynamics kJ/mol The relation describing how the enthalpy change of a reaction varies with temperature. ΔH(T₂) = ΔH(T₁) + ΔC_p(T₂ − T₁)

Thermochemical Equation Thermochemistry & Thermodynamics kJ/mol A balanced chemical equation that also states the enthalpy change for the amounts shown. aA + bB → cC, ΔH = x kJ

Arrhenius Theory Acids, Bases & Salts Dimensionless The theory defining an acid as a substance that produces H⁺ ions in water and a base as one that produces OH⁻ ions. HA → H⁺ + A⁻; BOH → B⁺ + OH⁻

Bomb Calorimeter Thermochemistry & Thermodynamics J A rigid sealed vessel used to measure the heat released by combustion at constant volume. q_V = ΔU

Chelate Effect Inorganic & Coordination Chemistry kJ/mol The greater stability of a complex containing a multidentate ligand compared with one containing equivalent monodentate ligands. ΔS favourable

Cryoscopic Constant Solutions & Colligative Properties K·kg/mol The freezing point depression produced by a one-molal solution of a non-electrolyte in a given solvent. K_f = RT_f²M / ΔH_fus

Deposition States of Matter & Gas Laws kJ/mol The direct conversion of a vapour into a solid without an intermediate liquid phase.

Ebullioscopic Constant Solutions & Colligative Properties K·kg/mol The boiling point elevation produced by a one-molal solution of a non-electrolyte in a given solvent. K_b = RT_b²M / ΔH_vap

Results for “Enthalpy”