chempirical
Tools

Every tool, built for the bench

Free, in the browser, no account. Each one checks the chemistry while you type, so an impossible input is caught before it becomes a wrong answer.

Draw and view structures

CovalentA structure editor that snaps to real bond angles and ring geometry. Valence, charges and stereo are checked as you draw. SMILES to structurePaste SMILES and get a clean skeletal formula, formula, mass and a 3D model. Download SVG, PNG, MOL or 3D SDF.

Spectroscopy

SignumOpen NMR, IR, UV-Vis and MS spectra. Pick peaks, integrate, correct the baseline and overlay spectra. NMR predictorEstimate 1H and 13C chemical shifts and multiplicities from a structure, then open the spectrum in Signum. Spectrum file converterRead JCAMP-DX, SPC, CSV and XY files in the browser and export CSV, JSON, JCAMP-DX or Excel.

Reaction calculations

Reaction scaleFix the amount of one reagent and get masses, volumes and moles for everything else from equivalents and density. StoichiometryBalance the equation, enter what you have, and see the limiting reagent, theoretical yield and excess. Equation balancerBalance any equation, including ions and redox half-reactions, with exact integer coefficients. Compound listPaste names, CAS numbers or SMILES and get one table with molar mass, physical data, pKa and GHS hazards, ready to copy or download.

Distillation and physical data

Fractional distillationPredict the fractions a column will give: boiling points at your pressure, Fenske plates and azeotrope warnings. Pressure–temperature nomographBoiling point at any pressure for a named compound, or from one known boiling point. Vapour pressureVapour pressure curves from Antoine constants, with the normal boiling point marked. Pressure unitsConvert between mbar, Torr, mmHg, atm, bar, kPa and psi, the units found on vacuum gauges.

Solutions and pH

Solutions and dilutionsWhat to weigh for a molar solution, how much stock to dilute, and how to make 1 M HCl from 37 % acid. pH and bufferspH of acids, bases and buffers from exact equilibria, including polyprotic acids and mixtures.

Properties and reference

Molar massMolar mass, exact mass, elemental composition and the isotope pattern for any formula or structure. Drug-likenessLipinski, Veber, Ghose and lead-likeness from a structure, with every descriptor shown. Periodic tableAll 118 elements with masses, electron configurations, electronegativity and physical data.

Data

Molecules48,000 compounds with structures, identifiers, melting and boiling points and density. ReactionsNamed reactions and curated procedures, with the ones you can scale directly. Safety data sheetsVendor SDS with their composition, linked to the compounds they contain.