Source: https://guthlabs.ai/docs/instruments/solution-mixing-neutralization-calculator/implementation/

instrument implementation / implementation-contract

# Solution Mixing / Neutralization Calculator implementation

A source-bound implementation contract for Solution Mixing / Neutralization Calculator; 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**: t4-027

**Effect**: Computation or source lookup only

## Input and validation requirements

- Division by zero occurs if V1+V2=0; reject zero or negative total volume.

- Unit mismatch, such as multiplying molarity by milliliters without converting to liters, creates a factor-of-1000 error.

- The neutralization calculation must reject or explicitly handle negative concentrations and negative volumes.

- pH calculation is undefined if an excess-reagent concentration is zero unless water autoionization or an appropriate equilibrium model is used.

- Using pH=-log10(excess concentration) for a weak acid/base, polyprotic species, buffer, or equivalence point can be materially wrong.

- Acid/base stoichiometric coefficients must be included; a generic H+ versus OH- comparison is not sufficient for species such as H2SO4, H3PO4, Ca(OH)2, or weak electrolytes.

- The implementation needs an explicit policy for non-additive volumes, activity corrections, temperature dependence of Kw, precipitation, gas evolution, and reactions other than neutralization.

## 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": {
    "operation": "same-solute_mixing",
    "solute": "NaCl",
    "C1_M": 0.2,
    "V1_L": 0.15,
    "C2_M": 0.05,
    "V2_L": 0.35
  },
  "expected_outputs": {
    "total_moles_mol": 0.0475,
    "total_volume_L": 0.5,
    "C_final_M": 0.095
  },
  "working": "n1=C1V1=0.200×0.150=0.0300 mol. n2=C2V2=0.050×0.350=0.0175 mol. n_total=0.0300+0.0175=0.0475 mol. V_total=0.150+0.350=0.500 L. C_final=n_total/V_total=0.0475/0.500=0.0950 M."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/solution-mixing-neutralization-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/solution-mixing-neutralization-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/solution-mixing-neutralization-calculator/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-tranche4/tranche4-results.json`