#chemistry

Atomic isotope reference data as an API, built on the NIST Atomic Weights and Isotopic Compositions. For every known nuclide: its element (atomic number Z and symbol), mass number, relative atomic mass, natural isotopic composition (abundance) and the element's standard atomic weight. Look an isotope up by label (C-12, U-238) or by symbol + mass, list every isotope of an element, rank isotopes by mass or natural abundance, or search. A precise physics and chemistry reference for science, education, lab and engineering apps. Distinct from element-level data.

api.oanor.com/isotopes-api

Faraday-law electrolysis maths as an API, computed locally and deterministically. The mass endpoint applies Faraday's first law of electrolysis, m = (Q·M)/(n·F) = (I·t·M)/(n·F), to give the mass of a substance deposited at a cathode or dissolved at an anode from the charge passed — or the current and time — the molar mass and the valence (electrons transferred per ion), with the Faraday constant 96485 C/mol. The charge endpoint inverts it to give the charge Q = (m·n·F)/M and, with a current, the plating time needed to deposit a target mass — the core sizing calculation for electroplating and anodising. The gas-volume endpoint computes the volume of gas evolved during electrolysis, moles = Q/(n·F) and volume = moles × 22.414 L/mol at STP, using the electrons per gas molecule (two for hydrogen, four for oxygen in water electrolysis). Molar mass is in g/mol, current in amperes, time in seconds, charge in coulombs and mass in grams. Everything is computed locally and deterministically, so it is instant and private. Ideal for electroplating, anodising, battery, hydrogen-production and chemistry-education app developers, plating-time and gas-yield tools, and electrochemistry teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is electrolysis (Faraday's laws); for cell potential and the Nernst equation use an electrochemistry Nernst API.

api.oanor.com/electrolysis-api

Colligative-properties chemistry maths as an API, computed locally and deterministically. The freezing-point endpoint computes the freezing-point depression ΔTf = i·Kf·m and the resulting lowered freezing point of a solution, from the molality, the cryoscopic constant (1.86 °C·kg/mol for water) and the van 't Hoff factor i — which is 1 for a non-electrolyte like sugar, about 2 for sodium chloride and about 3 for calcium chloride. The boiling-point endpoint computes the boiling-point elevation ΔTb = i·Kb·m and the raised boiling point, with the ebullioscopic constant (0.512 °C·kg/mol for water). The osmotic-pressure endpoint computes the van 't Hoff osmotic pressure Π = i·M·R·T from the molarity, the temperature and the van 't Hoff factor, the pressure that drives osmosis across a semipermeable membrane, returned in atmospheres, kilopascals and bar. Molality is in mol per kg of solvent, molarity in mol per litre of solution and temperature in kelvin. Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry-education, food-science, antifreeze, desalination and biology app developers, solution and de-icing tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is colligative properties of solutions; for a compound's molar mass use a molar-mass API and for dilution concentrations a dilution API.

api.oanor.com/colligative-api

Chemical reaction-stoichiometry maths as an API, computed locally and deterministically. The limiting-reagent endpoint takes two reactants with their amounts in moles and their balanced-equation coefficients and finds which one runs out first — the limiting reagent — by comparing the moles/coefficient ratio (the reaction extent), and returns how much of the excess reagent is left over. The yield endpoint computes the theoretical yield of a product, in moles and grams, from the limiting reagent and the product's stoichiometric coefficient and molar mass, n_product = n_limiting·(coeff_product/coeff_limiting), and — given the actual yield — the percent yield. The mole-mass endpoint converts between moles, mass and the number of particles for a given molar mass, using moles = mass / molar_mass and N = moles · Avogadro's number (6.02214076e23). Amounts are in moles, masses in grams and molar masses in g/mol. Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry-education, lab, pharmaceutical and chemical-engineering app developers, reaction-planning and yield tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is reaction stoichiometry; for a compound's molar mass from its formula use a molar-mass API and for solution concentrations a dilution API.

api.oanor.com/stoichiometry-api

Electrochemistry maths as an API, computed locally and deterministically. The nernst endpoint applies the Nernst equation, E = E° − (R·T/nF)·ln Q, to give the actual electrode or cell potential under non-standard conditions from the standard potential E°, the number of electrons transferred n, the reaction quotient Q and the temperature — at 25 °C this reduces to E = E° − (0.05916/n)·log10 Q, and a larger Q (more product) lowers the potential. The cell-potential endpoint computes a galvanic cell's standard EMF from the cathode and anode standard reduction potentials, E°cell = E°cathode − E°anode, together with the standard Gibbs free energy ΔG° = −nF·E°cell and whether the reaction is spontaneous. The equilibrium endpoint computes the equilibrium constant of a redox reaction, K = exp(nF·E°cell / RT), and the corresponding ΔG°, from the standard cell potential and the electrons transferred. Potentials are in volts, energies in kJ/mol, the Faraday constant is 96485 C/mol and the gas constant 8.314 J/mol·K. Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry-education, battery, corrosion, electroplating and electroanalytical app developers, galvanic-cell and redox tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is electrochemistry; for acid-base pH use a pH API and for reaction-rate kinetics an Arrhenius API.

api.oanor.com/nernst-api

Gas-mixture maths as an API, computed locally and deterministically. The partial-pressure endpoint applies Dalton's law — give a list of component partial pressures and it sums them to the total and returns each gas's mole fraction; or give a total pressure and a mole fraction to get a partial pressure; or component and total moles to get a mole fraction (and a partial pressure when a total pressure is supplied). The mole-fraction endpoint takes the moles of each component and returns every mole fraction and, with a total pressure, the partial pressures; supply the molar masses too and it adds the mass fractions and the average molar mass of the mixture. The effusion endpoint applies Graham's law, rate₁/rate₂ = √(M₂/M₁), to compare how fast two gases effuse or diffuse from their molar masses, naming the faster gas and the time ratio. Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry-education, laboratory, process and scuba app developers, gas-blending and stoichiometry tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is gas-mixture maths; for the ideal-gas law of a single gas use a gas-law API and for molar mass from a formula a molar-mass API.

api.oanor.com/gasmixture-api

Molar-mass and stoichiometry maths as an API, computed locally and deterministically. The molarmass endpoint parses any chemical formula — with parentheses, square brackets and hydrate dots, such as Ca(OH)2, [Fe(CN)6]3 or CuSO4·5H2O — against the IUPAC conventional atomic weights and returns the molar mass in grams per mole, the total atom count and the per-element breakdown with each element's mass contribution and mass percent. The convert endpoint moves between moles, mass in grams and number of molecules for a formula, using n = mass ÷ M = molecules ÷ Nₐ with Avogadro's number. The percent endpoint gives the percent composition by mass and, for a given sample mass, the mass of each element it contains. The formula is parsed locally, so it works for any valid formula, not just compounds in a database, and is instant and private. Ideal for chemistry-education, laboratory, pharmaceutical and science app developers, stoichiometry and lab-prep tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This computes molar mass from a formula; for compound database lookup use a chemistry API and for element properties an elements API.

api.oanor.com/molarmass-api

Colligative-properties maths for solutions as an API, computed locally and deterministically. The osmotic endpoint computes the osmotic pressure by the van 't Hoff equation, π = i·M·R·T, from the molarity, the temperature and the van 't Hoff factor (the number of dissolved particles per formula unit — 1 for sugar, 2 for NaCl, 3 for CaCl₂), reported in atmospheres, bar and kilopascals, and also solves the molarity back from a measured pressure. The freezing endpoint computes the freezing-point depression, ΔTf = i·Kf·m, from the molality and the cryoscopic constant (1.86 °C·kg/mol for water), and the new freezing point. The boiling endpoint computes the boiling-point elevation, ΔTb = i·Kb·m, from the ebullioscopic constant (0.512 °C·kg/mol for water), and the new boiling point. Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry, biology and food-science tools, reverse-osmosis and desalination estimates, antifreeze and de-icing formulation, lab and education apps. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is colligative-properties chemistry; for solution dilution use a dilution API and for pH and buffers use a pH API.

api.oanor.com/osmosis-api

pH and acid–base maths as an API, computed locally and deterministically. The ph endpoint converts freely between the four ways of describing acidity — the pH, the pOH, the hydronium-ion concentration [H+] and the hydroxide concentration [OH−]: give any one and it returns the others using pH = −log₁₀[H+], [OH−] = Kw/[H+] and pH + pOH = pKw, and classifies the solution as acidic, neutral or basic. The strong endpoint gives the pH of a strong acid or strong base from its molarity ([H+] = c for an acid, [OH−] = c for a base), warning when the solution is so dilute that water self-ionisation matters. The buffer endpoint applies the Henderson–Hasselbalch equation, pH = pKa + log₁₀([A−]/[HA]), to a buffer from a pKa and the conjugate-base-to-acid ratio (given directly or as two concentrations), and also handles a base buffer from a pKb. Kw defaults to 1×10⁻¹⁴ (25 °C) and can be overridden for other temperatures. Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry and biology lab tools, titration and buffer-prep apps, water-treatment and aquarium software, and science education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is pH and acid–base chemistry; for solution dilution and molarity use a dilution API.

api.oanor.com/phcalc-api

Arrhenius reaction-kinetics maths as an API, computed locally and deterministically. The rate-constant endpoint applies the Arrhenius equation k = A·exp(−Ea/RT), relating the rate constant, the pre-exponential (frequency) factor A, the activation energy Ea and the absolute temperature: give any three and it solves for the fourth, with the activation energy in joules or kilojoules per mole and the temperature in kelvin or Celsius. The activation-energy endpoint uses the two-point method — from two rate constants measured at two temperatures it returns the activation energy, Ea = R·ln(k2/k1)/(1/T1 − 1/T2), and the pre-exponential factor. The temperature-effect endpoint gives the factor by which the rate changes between two temperatures, k2/k1 = exp(−Ea/R·(1/T2 − 1/T1)), along with the Q₁₀ — the rate multiplier per 10 K rise — and the new rate constant if you supply the old one. The gas constant R is 8.314462618 J/(mol·K). Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry and chemical-engineering tools, reaction and process-design apps, shelf-life and stability modelling, and physics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is reaction kinetics; for the ideal gas law use a gas-law API and for radioactive decay use a half-life API.

api.oanor.com/arrhenius-api

Beer–Lambert spectroscopy maths as an API, computed locally and deterministically. The beer-lambert endpoint applies the law A = ε·c·l, where absorbance equals the molar absorptivity times the concentration times the optical path length: give any three of the four and it solves for the fourth (the path length defaults to the standard 1 cm cuvette when omitted), and it always reports the matching transmittance and percent transmittance. The transmittance endpoint converts between absorbance and transmittance in both directions, A = −log₁₀(T) and T = 10^(−A), and accepts a fraction or a percentage. The calibration endpoint reads a concentration off a linear calibration curve, A = slope·c + intercept, solving for the concentration from a measured absorbance or for the expected absorbance from a concentration. Units are whatever you supply consistently — for molar absorptivity in M⁻¹cm⁻¹, a path length in cm and absorbance dimensionless, the concentration comes out in molar. Everything is computed locally and deterministically, so it is instant and private. Ideal for analytical-chemistry and lab tools, spectrophotometer and assay apps, biotech and education software, and quality-control calculators. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is Beer–Lambert spectroscopy; for solution dilution and molarity use a dilution API and for chemical compound data use a chemistry API.

api.oanor.com/beerlambert-api

Laboratory dilution and molarity maths as an API, computed locally and deterministically. The dilution endpoint solves the standard C1·V1 = C2·V2 relation: give any three of the stock concentration, stock volume, final concentration and final volume and it returns the fourth, plus the volume of stock needed, the diluent to add (V2 − V1) and the dilution factor — and it warns you if the numbers would concentrate rather than dilute. The molarity endpoint ties together moles, molarity, volume, mass and molar mass via moles = molarity × volume(L) and mass = moles × molar mass: pass any sufficient subset (for example a target molarity, volume and molar mass) and it returns how much solute you need, with volumes in litres and millilitres and mass in grams and milligrams. The serial endpoint builds a serial-dilution series from a stock concentration, a dilution factor and a number of steps, giving the concentration at each tube and — if you pass a per-tube total volume — the transfer and diluent volumes for each step. Volumes accept litres, millilitres, centilitres, decilitres and microlitres; mass accepts grams, kilograms, milligrams and micrograms. Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry and biology lab tools, LIMS and bench apps, education and homework helpers, and pharmacy and pipetting calculators. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is a dilution and molarity calculator; for chemical-compound data and properties use a chemistry API and for the ideal gas law use a gas-law API.

api.oanor.com/dilution-api

Ideal-gas-law maths as an API, computed locally and deterministically. The ideal endpoint solves PV = nRT for whichever quantity you leave out: provide any three of pressure, volume, amount of substance (moles) and temperature, and it returns the fourth in several units. The combined endpoint applies the combined gas law, P₁V₁/T₁ = P₂V₂/T₂: give a first state and two quantities of the second state and it finds the missing one — handy for "what happens to the volume if I double the pressure" questions. The density endpoint computes the density of an ideal gas from the pressure, temperature and molar mass (ρ = P·M / R·T). Pressure accepts pascals, kPa, bar, atm, psi, mmHg and Torr; volume accepts m³, litres, mL and cubic feet; temperature accepts kelvin, Celsius and Fahrenheit; and the gas constant R is 8.314462618 J/(mol·K). Everything is computed in SI internally and is instant and private. Ideal for chemistry and physics education, lab and process tools, HVAC and scuba calculations, and engineering software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is ideal-gas thermodynamics; for the chemical elements and periodic-table data use an elements API.

api.oanor.com/gaslaw-api

Crystal structures as an API — powered by the Crystallography Open Database (COD), the open, public-domain collection of over 500,000 crystal structures of organic, inorganic, metal-organic compounds and minerals. Search the database by chemical formula (any standard casing — TiO2, Al2O3, H2O — is normalised automatically) or by free text over mineral names, titles and comments, then look up any structure to get its full crystallographic data: chemical and cell formula, space group (Hermann-Mauguin and Hall), the complete unit cell (a, b, c, alpha, beta, gamma and volume), the source publication (title, authors, journal, year, DOI) and a link to the CIF file. From quartz, calcite and diamond to anatase, corundum and diopside, it is ideal for materials science, solid-state chemistry, mineralogy, crystallography teaching and research tooling. This is a crystal-structure & materials database — distinct from molecule-property (chemistry / PubChem) and protein-structure (PDB) databases. Open data from the Crystallography Open Database (CC0 / public domain).

api.oanor.com/cod-api

Chemical compound data as an API, powered by NIH PubChem (>100 million compounds). Look up any compound by common name, PubChem CID or SMILES and get its molecular formula, molecular and exact mass, IUPAC name, canonical SMILES, InChI and InChIKey, plus physicochemical properties (XLogP, TPSA, formal charge, hydrogen-bond donor/acceptor counts, rotatable bonds, heavy-atom count). List a compound's synonyms and trade/registry names, or resolve a name to PubChem CIDs. Ideal for cheminformatics, lab software, education, drug-discovery tooling and scientific data pipelines.

api.oanor.com/chemistry-api

The complete periodic table as an API — all 119 chemical elements with their atomic and physical properties: atomic number and mass, category, phase, melting and boiling point, density, electron configuration, electronegativity, ionization energies and a short summary. Look up an element by symbol, atomic number or name, search and filter by category/phase/block, or fetch the whole table. Ideal for chemistry tools, education apps and science projects.

api.oanor.com/elements-api