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960 terms · page 38 of 40
System
Thermochemistry & Thermodynamics
Dimensionless
The specific part of the universe chosen for thermodynamic study, separated from everything else by a real or imaginary boundary.
Systematic Error
Analytical Chemistry & Spectroscopy
Various
An error that shifts every result in the same direction by a similar amount.
Temperature Coefficient
Chemical Kinetics & Catalysis
Dimensionless
The factor by which a reaction rate increases for a 10 °C rise in temperature.
Q₁₀ = k(T+10) / k(T)
Termolecular Reaction
Chemical Kinetics & Catalysis
L²/(mol²·s)
An elementary step requiring the simultaneous collision of three species.
rate = k[A][B][C]
Tertiary Structure
Biochemistry & Polymer Chemistry
Dimensionless
The complete three-dimensional folded shape of a single polypeptide chain.
Tetrahedral Geometry
Chemical Bonding & Molecular Structure
degrees
A molecular shape with four bonded atoms directed to the corners of a regular tetrahedron at 109.5°.
AX₄
Tetrahedral Splitting
Inorganic & Coordination Chemistry
cm⁻¹
The division of d orbitals under a tetrahedral field, with the e set below the t₂ set and a much smaller gap.
Δ_t = (4/9)Δ₀
Theoretical Yield
Stoichiometry & Chemical Reactions
g
The maximum mass of product that could be obtained from a given quantity of limiting reagent, assuming complete conversion.
m = n(limiting) × ratio × M
Thermal Decomposition
Stoichiometry & Chemical Reactions
°C
The breakdown of a compound into simpler substances brought about solely by heating.
AB →(Δ) A + B
Thermite Reaction
Stoichiometry & Chemical Reactions
kJ/mol
A highly exothermic reaction in which aluminium powder reduces a metal oxide to the molten metal.
Fe₂O₃ + 2Al → 2Fe + Al₂O₃
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
Thermodynamic Equilibrium
Thermochemistry & Thermodynamics
kJ/mol
The state in which a system's properties no longer change with time and all driving forces are balanced.
ΔG = 0
Thermodynamic Equilibrium Constant
Chemical Equilibrium
Dimensionless
The dimensionless equilibrium constant defined using activities rather than concentrations or pressures.
K° = Π a_i^ν
Thermodynamics
Thermochemistry & Thermodynamics
J
The branch of science dealing with energy, its transformations, and the direction in which processes occur.
Thermonuclear Reaction
Nuclear & Radiochemistry
K
A fusion reaction sustained by the extremely high temperatures of the reacting material itself.
Thermoplastic
Biochemistry & Polymer Chemistry
°C
A polymer that softens on heating and hardens again on cooling, reversibly and repeatedly.
Thermosetting Polymer
Biochemistry & Polymer Chemistry
°C
A polymer that sets permanently on first heating and cannot be softened again.
Thin Layer Chromatography
Analytical Chemistry & Spectroscopy
Dimensionless
A chromatographic technique using a thin layer of adsorbent coated on a flat plate.
Third Law of Thermodynamics
Thermochemistry & Thermodynamics
J/(mol·K)
The entropy of a perfect crystalline substance approaches zero as the temperature approaches absolute zero.
S → 0 as T → 0 K
Three-Centre Two-Electron Bond
Chemical Bonding & Molecular Structure
kJ/mol
A bond in which a single pair of electrons is shared between three atoms rather than two.
A···H···B
Threshold Energy
Chemical Kinetics & Catalysis
kJ/mol
The minimum total energy that colliding molecules must possess for the collision to be capable of reaction.
E_threshold = Ea + E_average
Titration
Acids, Bases & Salts
mol/L
A quantitative technique in which a solution of known concentration is added to another until the reaction between them is exactly complete.
n₁ / n₂ = a / b
Titration Curve
Acids, Bases & Salts
Dimensionless
A plot of pH against the volume of titrant added during an acid–base titration.
Transition Element
Atomic Structure & Periodicity
Dimensionless
An element whose atom or a stable ion has a partially filled d subshell.
(n−1)d¹⁻⁹