Beer–Lambert Law (Absorbance) Calculator

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Chemistry & Materials

Tranche

tranche-5

Evidence ID

t5-014

Ledger rows

1

No ledger note is attached.

Review findings

NEEDS_REVIEW because the exact unit ambiguity is that no units are specified for ε, l, or c, so numerically identical inputs can yield different results depending on whether length is in cm, mm, or another unit and whether concentration is mol/L or another concentration unit. The formula itself is correct when units are compatible and the Beer–Lambert assumptions hold.

Formula and scope findings

• The formula A=εlc is the standard Beer–Lambert relationship, but the claim that any three inputs are sufficient is incomplete without requiring the denominator in the rearranged formula to be nonzero.
• The specification does not define physical validity constraints: path length, concentration, and molar absorptivity should generally be positive, and absorbance should normally be nonnegative for the stated use.
• The specification does not state that the calculation applies at a specified wavelength under consistent measurement conditions, such as a homogeneous sample and appropriate baseline correction.

Unit assumptions

• A is dimensionless.
• If l is in cm, c is in mol/L, and ε is in L·mol^-1·cm^-1, then A=εlc is dimensionally consistent.
• If l is supplied in mm, it must be converted to cm before using ε in L·mol^-1·cm^-1.
• The wavelength, solvent, temperature, and sample conditions are assumed fixed for the supplied ε.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The zero-path-length input makes the concentration calculation undefined. With the specified plain-arithmetic engine, an unchecked implementation can return Infinity rather than rejecting the input. Unit ambiguity can additionally produce a tenfold concentration error.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

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

{
  "inputs": {
    "A": 0.6,
    "epsilon": 15000,
    "epsilon_units": "L mol^-1 cm^-1",
    "l": 1,
    "l_units": "cm",
    "c": null,
    "c_units": "mol L^-1"
  },
  "expected_outputs": {
    "c": 0.00004,
    "c_units": "mol L^-1"
  },
  "working": "c=A/(εl)=0.600/(15000×1)=0.600/15000=0.0000400 mol L^-1=4.00×10^-5 mol L^-1."
}

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_CLEAN
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json