Reaction Stoichiometry / Limiting Reagent Solver implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t6-018

Effect

Computation or source lookup only

Input and validation requirements

• Division by zero occurs if a parsed stoichiometric coefficient is zero or if a molar mass is zero or missing.
• Negative masses or moles produce chemically invalid results unless rejected.
• If every reactant amount is zero, the limiting reagent is mathematically tied or undefined; the UI needs an explicit policy.
• Mass and mole units can be mixed incorrectly if each reactant row does not carry an explicit unit and conversion path.
• A product mass cannot be computed without a valid product formula and molar mass.
• Unbalanced equations, malformed formulas, unknown elements, and coefficients rounded during balancing can silently produce incorrect limiting-reagent and yield results.
• Real samples may contain impurities, hydrates, solutions with concentration/volume, or percent yield; treating entered sample mass as pure compound should be clearly labeled as an assumption.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "balanced_equation": "2 H2 + O2 -> 2 H2O",
    "reactants": {
      "H2": {
        "amount": 4.032,
        "unit": "g",
        "molar_mass_g_per_mol": 2.016
      },
      "O2": {
        "amount": 32,
        "unit": "g",
        "molar_mass_g_per_mol": 32
      }
    },
    "requested_products": [
      "H2O"
    ],
    "product_molar_masses_g_per_mol": {
      "H2O": 18.015
    }
  },
  "expected_outputs": {
    "limiting_reagent": "none; stoichiometric mixture",
    "reaction_extent_mol": 1,
    "products": {
      "H2O": {
        "amount_mol": 2,
        "theoretical_yield_g": 36.03
      }
    },
    "reactants_remaining": {
      "H2": {
        "amount_mol": 0,
        "mass_g": 0
      },
      "O2": {
        "amount_mol": 0,
        "mass_g": 0
      }
    }
  },
  "working": "n(H2) = 4.032 g / 2.016 g/mol = 2.000 mol. n(O2) = 32.00 g / 32.00 g/mol = 1.000 mol. Ratio for H2 = 2.000/2 = 1.000 mol reaction; ratio for O2 = 1.000/1 = 1.000 mol reaction. Both ratios are equal, so neither reagent is limiting. Extent = 1.000 mol. n(H2O) = 2*1.000 = 2.000 mol. Theoretical mass H2O = 2.000 mol * 18.015 g/mol = 36.030 g. H2 remaining = 2.000 - 2*1.000 = 0 mol; O2 remaining = 1.000 - 1*1.000 = 0 mol."
}

Other records

Sources and evidence

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

• VERIFIED_LEDGER.json
• evidence-tranche6/tranche6-results.json