Source: https://guthlabs.ai/docs/instruments/reaction-stoichiometry-limiting-reagent-solver/implementation/

instrument implementation / implementation-contract

# Reaction Stoichiometry / Limiting Reagent Solver implementation

A source-bound implementation contract for Reaction Stoichiometry / Limiting Reagent Solver; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## 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

[01**Overview**](<https://guthlabs.ai/docs/instruments/reaction-stoichiometry-limiting-reagent-solver/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/reaction-stoichiometry-limiting-reagent-solver/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/reaction-stoichiometry-limiting-reagent-solver/qualification/>)

## 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`