Terms starting with H
41 terms · page 1 of 2
Half-Life of a Reaction
The time required for the concentration of a reactant to fall to half its initial value.
Electrochemistry & RedoxHalf-Reaction
An equation showing either the oxidation or the reduction part of a redox process, including the electrons transferred.
Stoichiometry & Chemical ReactionsHalf-Reaction Method
A technique for balancing redox equations by splitting them into separate oxidation and reduction half-equations.
Organic ChemistryHaloalkane
An alkane in which one or more hydrogen atoms have been replaced by halogen atoms.
Atomic Structure & PeriodicityHalogens
The group 17 elements — fluorine through astatine — which are one electron short of a full outer shell.
Thermochemistry & ThermodynamicsHeat
Energy transferred between a system and its surroundings solely because of a temperature difference.
Thermochemistry & ThermodynamicsHeat Capacity at Constant Pressure
The heat needed to raise a system's temperature by one kelvin while pressure is held constant.
Thermochemistry & ThermodynamicsHeat Capacity at Constant Volume
The heat needed to raise a system's temperature by one kelvin while its volume is held fixed.
Atomic Structure & PeriodicityHeisenberg Uncertainty Principle
The principle that the position and momentum of a particle cannot both be known to arbitrary precision at the same time.
Thermochemistry & ThermodynamicsHelmholtz Free Energy
The thermodynamic potential that determines spontaneity at constant temperature and volume.
Acids, Bases & SaltsHenderson–Hasselbalch Equation
The equation giving the pH of a buffer from the pKa of its acid and the ratio of conjugate base to acid.
Solutions & Colligative PropertiesHenry's Law
The solubility of a gas in a liquid is directly proportional to the partial pressure of that gas above the liquid.
Thermochemistry & ThermodynamicsHess's Law
The total enthalpy change of a reaction is the same regardless of the route taken, provided the initial and final states are identical.
Chemical Kinetics & CatalysisHeterogeneous Catalysis
Catalysis in which the catalyst is in a different phase from the reactants, usually a solid with gaseous or liquid reagents.
Chemical EquilibriumHeterogeneous Equilibrium
An equilibrium involving species present in more than one phase.
Foundations of ChemistryHeterogeneous Mixture
A mixture in which the components remain physically distinct, so composition varies from one region of the sample to another.
States of Matter & Gas LawsHexagonal Close Packing
A close-packed arrangement in which layers of spheres repeat in an ABAB sequence.
Inorganic & Coordination ChemistryHigh Spin Complex
A complex in which electrons occupy the higher d orbitals singly before pairing, maximising unpaired spins.
Analytical Chemistry & SpectroscopyHigh-Performance Liquid Chromatography
A technique in which a liquid mobile phase is pumped at high pressure through a column of very fine stationary phase.
Analytical Chemistry & SpectroscopyHigh-Resolution Mass Spectrometry
Mass spectrometry capable of measuring mass to four or more decimal places, allowing molecular formulae to be determined.
Chemical Bonding & Molecular StructureHOMO and LUMO
The highest occupied and lowest unoccupied molecular orbitals, which together govern a molecule's reactivity and spectroscopy.
Chemical Kinetics & CatalysisHomogeneous Catalysis
Catalysis in which the catalyst is in the same phase as the reactants.
Chemical EquilibriumHomogeneous Equilibrium
An equilibrium in which all the reacting species are present in the same phase.
Foundations of ChemistryHomogeneous Mixture
A mixture whose composition and properties are uniform throughout, with no visible boundary between the components.