Browse the dictionary
960 terms · page 6 of 40
Buffer Range
Acids, Bases & Salts
Dimensionless
The span of pH values over which a buffer works effectively, conventionally one unit either side of its pKa.
pH = pKa ± 1
Buffer Solution
Acids, Bases & Salts
Dimensionless
A solution that resists changes in pH when small amounts of acid or base are added.
Calcination
Stoichiometry & Chemical Reactions
°C
The heating of an ore or compound to high temperature in the absence or limited supply of air to drive off volatile matter.
MCO₃ →(Δ) MO + CO₂
Calibration Curve
Analytical Chemistry & Spectroscopy
Various
A plot of instrument response against known analyte concentration, used to determine unknowns.
y = mx + c
Calomel Electrode
Electrochemistry & Redox
V
A reference electrode based on the equilibrium between mercury, mercury(I) chloride and chloride ions.
Hg₂Cl₂ + 2e⁻ ⇌ 2Hg + 2Cl⁻
Calorific Value
Thermochemistry & Thermodynamics
kJ/g
The heat released by the complete combustion of unit mass of a fuel.
CV = ΔH_c / molar mass
Calorimetry
Thermochemistry & Thermodynamics
J
The experimental measurement of heat exchanged during a physical or chemical change.
q = mcΔT
Cannizzaro Reaction
Organic Chemistry
Dimensionless
The disproportionation of an aldehyde with no alpha hydrogen under concentrated alkali into an alcohol and a carboxylate.
2RCHO + OH⁻ → RCH₂OH + RCOO⁻
Capillary Action
States of Matter & Gas Laws
m
The spontaneous rise or fall of a liquid in a narrow tube, driven by the balance between adhesion and cohesion.
h = 2γcosθ / ρgr
Carbanion
Organic Chemistry
Dimensionless
An organic ion in which a carbon atom bears a negative charge and a lone pair.
R₃C⁻
Carbocation
Organic Chemistry
Dimensionless
An organic ion in which a carbon atom bears a positive charge and only six valence electrons.
R₃C⁺
Carbohydrate
Biochemistry & Polymer Chemistry
Dimensionless
A biomolecule composed of carbon, hydrogen and oxygen, usually with hydrogen and oxygen in the ratio found in water.
Cₓ(H₂O)_y
Carbon-13 NMR
Analytical Chemistry & Spectroscopy
ppm
An NMR technique that detects the carbon-13 nucleus to reveal the carbon skeleton of a molecule.
δ 0–220 ppm
Carboxylic Acid
Organic Chemistry
Dimensionless
A compound containing a carboxyl group, in which a carbonyl and a hydroxyl group share the same carbon.
R–COOH
Carnot Cycle
Thermochemistry & Thermodynamics
Dimensionless
An idealised reversible cycle of two isothermal and two adiabatic steps that defines the maximum efficiency of a heat engine.
η = 1 − T_cold / T_hot
Catalysis
Chemical Kinetics & Catalysis
Dimensionless
The process by which a reaction rate is increased through the action of a catalyst.
Catalyst
Chemical Kinetics & Catalysis
Dimensionless
A substance that increases the rate of a reaction by providing an alternative pathway of lower activation energy, without being consumed.
Catalyst Poisoning
Chemical Kinetics & Catalysis
Dimensionless
The loss of catalytic activity caused by a substance binding irreversibly to the active sites.
Cathode
Electrochemistry & Redox
Dimensionless
The electrode at which reduction occurs.
Cathodic Protection
Electrochemistry & Redox
V
The prevention of corrosion by forcing the metal to be protected to act as a cathode.
Cation
Foundations of Chemistry
C (charge)
A positively charged ion produced when an atom or molecule loses one or more electrons.
M → Mⁿ⁺ + n e⁻
Cell Notation
Electrochemistry & Redox
Dimensionless
A shorthand convention for representing an electrochemical cell using vertical lines for phase boundaries.
Zn(s) | Zn²⁺(aq) ‖ Cu²⁺(aq) | Cu(s)
Cell Potential
Electrochemistry & Redox
V
The difference in electrical potential between the two electrodes of an electrochemical cell.
E_cell = E_red(cathode) − E_red(anode)
Cellular Respiration
Biochemistry & Polymer Chemistry
kJ/mol
The oxidation of nutrients within cells to release energy as ATP.
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O