Parse bounded chemical formulas, groups, hydrates and explicit charges with a versioned local CIAAW-based atomic-weight dataset.
01 / PURPOSE-SPECIFIC INPUTS
02 / RESULT & SUPPORTING WORK
CIAAW 2024 abridged central values represent conventional natural-isotope composition, including elements whose full standard weight is an interval. They are not exact isotope masses. Different natural or enriched isotope compositions can change the mass. Isotope-label syntax is not supported.
| Element | Atoms | Weight used | Contribution g/mol | Mass % |
|---|---|---|---|---|
| H | 2 | 1.008 | 2.016 | 11.1907 |
| O | 1 | 15.999 | 15.999 | 88.8093 |
Uses the current formula’s unrounded molar mass (≈ 18.015 g/mol). Displayed values are rounded; the conversion retains full calculation precision.
≈ 0.0555092978074 mol
mol = grams / molar mass ≈ 1 g / (18.015 g/mol) ≈ 0.0555092978074 mol
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A bounded parser counts elements in the written formula unit and multiplies by a versioned local atomic-weight snapshot. Dataset assumptions, isotope limitations and charge ambiguity remain visible.
See bounded nested-group and hydrate parsing, exact atom counts, conventional mass contributions and an attributed offline element dataset.
Molecular Weight Calculator inputs and calculations remain in browser memory. No external processing API receives entered measurements, formulas, dates or financial values. Ordinary website page requests may still be logged. Clipboard access occurs only when you choose Copy Result.
A local versioned snapshot uses CIAAW Abridged Standard Atomic Weights 2024 central values. Elements without a standard atomic weight use explicitly flagged representative isotope mass numbers from CIAAW’s NUBASE2020 compilation; these are rough mass approximations, not exact nuclide masses.
Case-sensitive element symbols, positive integer subscripts, parentheses, nested groups, square brackets and hydrate separators are supported. Unicode subscript digits are normalized. Leading coefficients multiply the complete formula part.
Explicit terminal caret charges such as SO4^2- or Fe^3+ are accepted. A simple terminal sign is accepted only when it does not make a digit ambiguous. Inputs such as Fe3+ are rejected with guidance to state the intended charge; electron-mass corrections are not modeled.
No. Middle dot and ASCII period are strictly separators between hydrate/formula parts. CuSO4·5H2O adds five water units. Decimal stoichiometric subscripts and explicit isotope-label syntax are not supported.
Abridged weights reflect chosen conventional natural-isotope composition and uncertainty. Isotopic enrichment and different standard-weight versions can change the result. NIST lists water at 18.0153 and carbon dioxide at 44.0095, close to this snapshot’s conventional 18.015 and 44.009.
Formula length is at most 256 characters, nesting at most eight levels, individual subscripts/multipliers at most 100000 and total atoms at most one million. Unknown elements, unbalanced or empty groups and zero/negative subscripts are rejected.