Molar Mass / Formula Mass Calculator

Inspectable records

Ledger state

The current ledger marks this instrument verified with errata that must be applied at binding time.

Area

Chemistry & Materials

Tranche

tranche-6

Evidence ID

t6-006

Ledger rows

1

No ledger note is attached.

Review findings

The arithmetic algorithm is correct for the stated scope, and the four vectors cover a simple formula, a hydrate, nested parentheses, and a single-element boundary case. The verdict is NEEDS_REVIEW because the atomic-weight data source, precision/rounding policy, and exact accepted formula grammar are not specified, while the phrase 'any chemical formula string' overclaims the documented parser scope.

Formula and scope findings

• The core formula M = Σ(nᵢ·Aᵢ) is the standard molar-mass method and is correct for neutral formulas with integer atom counts.
• The claim 'any chemical formula string' is too broad unless the grammar explicitly defines support for ionic charges, isotope notation, bracketed coordination complexes, fractional stoichiometric coefficients, leading coefficients, dot/middle-dot hydrate notation, and phase labels.
• 'IUPAC 2021 standard atomic weights / CODATA' is ambiguous: standard atomic weights and CODATA fundamental constants are different data sources. The instrument must identify one atomic-weight table, its revision, and its rounding policy.
• The specification does not state whether output is rounded, and to how many decimal places or significant figures. Different atomic-weight precision and rounding choices can change displayed totals.
• The parser must distinguish a hydrate separator such as '·' from unsupported punctuation and must define whether whitespace around the separator is allowed.

Unit assumptions

• Atomic weights Aᵢ are conventional relative atomic masses expressed numerically in unified atomic mass units per atom; the numerical molar-mass value is used in g/mol because 1 u per particle corresponds numerically to 1 g/mol.
• The test vectors use these conventional atomic weights in g/mol: H=1.008, O=15.999, Cu=63.546, S=32.06, Al=26.9815385, N=14.007, Ca=40.078.
• Outputs are total molar mass in g/mol and per-element contributions in g/mol.
• The formula represents one mole of formula units and contains integer, nonnegative atom counts.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The extreme-count vector exposes a precision-loss break if the parser accepts subscripts above JavaScript's safe-integer limit instead of rejecting them. The convention probe also exposes a severe interpretation hazard if element-symbol capitalization is not enforced.

Errata and corrections

Tranche errata

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "formula": "H2O",
    "atomic_weights": {
      "H": 1.008,
      "O": 15.999
    }
  },
  "expected_outputs": {
    "molar_mass_g_per_mol": 18.015,
    "element_mass_breakdown_g_per_mol": {
      "H": 2.016,
      "O": 15.999
    }
  },
  "working": "Parse counts: H₂O gives n(H)=2 and n(O)=1. H contribution = 2 × 1.008 = 2.016 g/mol. O contribution = 1 × 15.999 = 15.999 g/mol. Total = 2.016 + 15.999 = 18.015 g/mol."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json · VERIFIED_WITH_ERRATA
• evidence-tranche6/tranche6-results.json
• BOUNDARY_HAZARD_CATALOG.json