Chemistry data tables
Every reference value the site’s calculations use — sortable, filterable, and sourced.
Showing 50 of 50 tables
Part I · Matter and atoms
Part III · Energy and change
- Standard thermodynamic data (298.15 K) Standard enthalpies and Gibbs energies of formation and standard molar entropies of about 140 elements, compounds and aqueous ions. Every reaction enthalpy, entropy change, equilibrium constant and Ellingham line in the thermochemistry and thermodynamics units is computed from this table. 140 entries
- Average bond enthalpies The average enthalpy needed to break one mole of a given bond in gas-phase molecules. They let you estimate reaction enthalpies for gas reactions when formation data are missing. 39 entries
- Melting and boiling: enthalpies and entropies Enthalpies of fusion and vaporization of common substances and metals at their normal melting and boiling points, with the transition entropies ΔS = ΔH/T. Trouton’s rule and the kinks of Ellingham lines come from this table. 60 entries
- Triple points and critical points Triple points, critical points and the 1 atm boiling (or sublimation) points of common substances. A substance whose triple-point pressure exceeds 1 atm — such as CO₂ — can only sublime at ordinary pressure. 7 entries
- Heat capacities of solid elements (25 °C) Molar heat capacities and specific heats of 21 solid elements at 298.15 K and their ratio to the Dulong–Petit value 3R; copper, silver and gold also carry the standard entropies obtained by integrating low-temperature heat capacities. 21 entries
- Vapour pressures of common liquids Saturated vapour pressures of diethyl ether, acetone, ethanol, water and toluene at several temperatures, with their normal boiling points and enthalpies of vaporization. The vapour-pressure curves and boiling-point–altitude relations on this site are computed from these equations. 5 entries
- Salt solubility versus temperature Solubilities of six salts in grams per 100 g of water from 0 to 100 °C, with their enthalpies of solution at infinite dilution. Salts with a positive enthalpy of solution become more soluble on warming. 6 entries
- Henry’s-law constants of gases in water Henry’s solubility constants at 25 °C and their temperature coefficients, with the 0 °C constants and air-saturated concentrations computed from them. 5 entries
- Effective van ’t Hoff factors (25 °C) Effective van ’t Hoff factors i = νφ computed from Pitzer osmotic coefficients. In dilute solution i falls short of the ion count ν, most of all for doubly charged ions (MgSO₄); in concentrated solution hydration pushes it back up. 4 entries
- Equilibrium constants The equilibrium constants, temperatures and reaction enthalpies used in the chemical-equilibrium unit. Every K(T) on the benches is computed from these values via van ’t Hoff or thermodynamic data. 11 entries
- Ammonia equilibrium: measured and computed Equilibrium ammonia percentages measured over an iron catalyst for a 3 : 1 hydrogen–nitrogen feed in 1923–1924, beside the values this site computes from NIST thermodynamic data for ideal gases. 35 entries
- Rate constants and activation energies Rate laws, rate constants and activation energies used in the reaction-rates unit — classic measurements, and model values where marked. 9 entries
- Enzyme kinetic parameters Michaelis constants KM, turnover numbers kcat and catalytic efficiencies kcat/KM of several enzymes, as used on the catalysis bench. 4 entries
Part IV · Reactions in solution
- Acid dissociation constants (25 °C) Stepwise pKa values of common weak acids and conjugate acids of weak bases — the table behind every acid–base calculation on this site. 41 entries
- Acid–base indicators Transition ranges, pKa values, and the colour of each form. The solution colours on the lab bench are computed from these forms’ absorption bands. 7 entries
- Solubility products (25 °C) Solubility products of common sparingly soluble salts, their molar solubilities in pure water and the observed colours of the precipitates, plus acid solubility products of metal sulfides. Every precipitation calculation in the precipitation and complex-ion unit uses this table. 33 entries
- Formation constants of complex ions Stepwise (log K) and cumulative (log β) formation constants of metal ions with ammonia, halides, thiosulfate, thiocyanate and hydroxide. The copper–ammine distribution, silver chloride dissolving in ammonia and the amphoteric hydroxides are all computed from this table. 42 entries
- Stability constants of chelates and EDTA complexes Stepwise formation constants of ethylenediamine complexes, the Co²⁺–NH₃ system, and the 1 : 1 formation constants of 13 metal ions with EDTA. The chelate-effect and conditional-EDTA calculations use this table; ammonia, halide and other monodentate systems are in the table of formation constants of complex ions. 30 entries
- Standard electrode potentials (25 °C) Standard reduction potentials of nearly a hundred couples, from the strongest oxidising agents to the strongest reducing agents. Every cell voltage, Nernst line, electrolysis prediction, Frost diagram and Pourbaix diagram in the redox unit is computed from this table. 96 entries
- Hydrogen overpotentials on metal cathodes Potentials and overpotentials of 11 cathodes measured by Tafel in 1905 in 2 N sulfuric acid at about 12 °C and 0.1 A/cm², with the extra energy the overpotential costs per mole of H₂. 11 entries
- Ligand-field splittings, absorption bands and colours Octahedral (or tetrahedral) splittings Δ, spin-allowed d–d absorption bands, free-ion pairing energies P and observed colours of transition-metal complexes. The crystal-field, spin-state and colour widgets and the spectrophotometer experiment all compute from this table. 25 entries
- Racah parameters B and nephelauxetic ratios β d–d bands of chromium(III) and nickel(II) complexes, with the Δo, Racah parameter B and β = B(complex)/B(free ion) computed from them. The values of β rank the nephelauxetic series. 9 entries
- Carbonyl stretching frequencies ν(CO) C–O stretching frequencies of free CO, the isoelectronic hexacarbonyls and [Ni(CO)₃L]. The more electron-rich the metal, the stronger the π back-donation and the lower ν(CO). 12 entries
- Mean activity coefficients of 1:1 electrolytes Measured γ± of NaCl and HCl in water at 25 °C beside the values of the Debye–Hückel limiting law, the extended law (å = 4.7 Å) and the Davies equation, with the Debye length at each molality. 10 entries
- Water-exchange rates of aqua metal ions First-order rate constants for exchange of one coordinated water molecule at 25 °C (¹⁷O NMR), the half-lives and Eyring Gibbs energies of activation that follow, and the ligand-field activation energy for octahedron → square pyramid. 14 entries
Part V · The elements
- Nuclide data: masses, binding energies and half-lives All 253 stable nuclides (NUBASE2020) with atomic mass, binding energy per nucleon and natural abundance, plus the half-lives, decay modes and uses of the radionuclides used on this site. 297 entries
- s-block energetics The three energy steps that turn the alkali and alkaline-earth metals into hydrated ions — atomisation, ionisation and the cycle-derived hydration enthalpy — with the ΔH°, ΔG° of their reactions with water and their standard potentials. 10 entries
- Solubility of group-2 hydroxides and sulfates Moles dissolved per kilogram of water in saturated solutions at 20 °C: the hydroxides become more soluble from Be to Ba, the sulfates less soluble. 10 entries
- Typical radiation doses From a dental X-ray to acute radiation sickness: typical doses from natural background, medical imaging, dose limits and acute exposure — to put mSv and Gy on a real-world scale. 15 entries
- Inert-pair effect: potentials of the N → N−2 couples Standard potentials for reducing the group oxidation state of groups 13–15 by two (25 °C, acid); at period 6 (Tl, Pb, Bi) they jump above +1.25 V. 11 entries
- Properties of the halogens Melting and boiling points, X–X and H–X bond enthalpies, electron affinities, cycle-derived X⁻ hydration enthalpies, standard potentials and absorption maxima of F₂, Cl₂, Br₂ and I₂. 4 entries
- Oxidation states of the first transition series The positive oxidation states of scandium to zinc, with their d-electron counts, how common they are and a representative species. 33 entries
- Metallic radii of the transition metals 12-coordinate metallic radii of the three transition series, groups 3–12: the period-5 and period-6 members of a group are almost the same size (the lanthanide contraction). 30 entries
- Absorption bands of ions (teaching fits) The absorption bands behind the site’s computed colours of first-row and lanthanide ions: positions are literature maxima, and ε values are approximate fits chosen to reproduce the observed colours. 36 entries
- Properties of the lanthanides 4f-electron counts, 8-coordinate ionic radii, standard potentials and aqueous colours of Ln³⁺: the radius shrinks smoothly while E°(Ln³⁺/Ln) barely changes. 15 entries
Part VI · Measurement and analysis
- Critical values of Student’s t Two-sided critical values of t, used for confidence intervals x̄ ± t·s/√n and for t tests. Degrees of freedom ν = n − 1 (n − 2 for a calibration line). 35 entries
- Critical values for the Grubbs test Testing one suspect value: if G = |suspect − x̄|/s exceeds the critical value, the value is an outlier at that confidence level. 31 entries
- Tolerances of class A volumetric glassware Class A tolerances of pipettes, volumetric flasks and burettes at 20 °C (class B is twice as wide), with the standard uncertainty for a rectangular distribution. 19 entries
- Partition coefficients (25 °C) Partition coefficients lg K_D of neutral molecules between an organic solvent and water (lg P for 1-octanol–water), with the pKa that makes the distribution ratio D depend on pH. The separating funnel and the pH-extraction bench of the extraction lesson use these values. 6 entries
- UV–visible absorption bands and molar absorptivities Literature wavelengths and ε for the solutions on the virtual spectrophotometer, beside the ε the site’s teaching fit gives at the same wavelength — the two agree within a few per cent. 11 entries
- Analytical lines for atomic spectroscopy Resonance lines used in flame emission and atomic absorption: excitation energy, the excited fraction at 2500 K (air–acetylene flame) and 6000 K (ICP), and the Doppler width at 2500 K — all computed from the line wavelength. 9 entries
- McReynolds constants of GC stationary phases How much higher the retention index of five probes is on a phase than on squalane: benzene (X′), 1-butanol (Y′), 2-pentanone (Z′), 1-nitropropane (U′) and pyridine (S′). The larger the sum, the more polar the phase. The chromatogram simulator places non-alkanes with these values. 4 entries
- Infrared vibrations of small molecules and oxo-anions Fundamental vibrations of H₂O, CO₂, SO₂, NH₃ and CH₄ (gas) and of CO₃²⁻, NO₃⁻ and SO₄²⁻: wavenumber, symmetry, degeneracy, and infrared and Raman activity. 29 entries
- Reference electrode potentials (25 °C) Potentials of common reference electrodes against the standard hydrogen electrode. A reported potential must name its reference; converting between scales only means adding or subtracting these values. 8 entries
- Limiting ionic conductivities (25 °C) Molar conductivities λ° and diffusion coefficients of ions at infinite dilution in water. By Kohlrausch’s law an electrolyte’s Λ° is the sum of its ions’ λ°; every curve in the conductometry lesson is computed from this table. 22 entries
- Primary standards for titrimetry Common primary standards: molar mass (computed from the formula), the titrant each standardises, the stoichiometry, the mass that uses about 40 mL of titrant, and how to dry and use it. 8 entries
- pH standard buffers (25 °C) pH values of the NIST/IUPAC primary standards at 25 °C. Every pH-meter calibration traces back to these solutions; the everyday technical buffers 4.01, 7.00 and 10.01 are made against them. 9 entries
- Indicators for complexometric, redox and precipitation titrations Eriochrome Black T, redox indicators, the Mohr, Volhard and Fajans indicators and starch: transition ranges, colour changes and uses. Transition ranges are computed from each indicator’s equilibrium constants. 9 entries
- Gravimetric weighing forms and factors Weighing forms, molar masses and gravimetric factors F = aM(analyte)/bM(weighing form) for common gravimetric methods, all computed from the formulas. 5 entries