Source: https://guthlabs.ai/docs/instruments/van-t-hoff-factor-estimator/mechanism/

instrument mechanism / verified-clean

# Van't Hoff Factor Estimator mechanism

The inspectable method record for Van't Hoff Factor Estimator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The core van't Hoff ratio is standard under the stated unit and experimental-equivalence assumptions, but the specification is incomplete for i_ideal and for percent dissociation/association. Require explicit behavior selection, dissociation particle count or association aggregation number, and validation of the physical output range before labeling the result.

- i = ΔT_measured / ΔT_calculated is valid only when both temperature changes use the same solvent, solute concentration basis, and colligative-property context; this equivalence is not stated.

- i_ideal cannot be determined from solute formula alone without explicit dissociation stoichiometry and an assumption of complete dissociation.

- For dissociation into ν particles per formula unit, the standard percent-dissociation formula is 100 × (i - 1) / (ν - 1); this formula is missing from the specification.

- Association is not defined. For aggregation into n-mers, a commonly used model is percent association = 100 × (1 - i) / (1 - 1/n), but the aggregation model and n are absent.

- The output label 'percent dissociation/association' is ambiguous unless the instrument requires the user to select dissociation versus association and provide the corresponding stoichiometry.

## Units and conventions

- ΔT_measured and ΔT_calculated must both be temperature differences, not absolute temperatures, and must use the same units.

- Temperature differences have the same numerical magnitude in degrees Celsius and kelvin: 1 °C difference = 1 K difference.

- ΔT_calculated is assumed to be the nonelectrolyte value for the same solvent, solute concentration, and relevant colligative property.

- For dissociation vectors, i_ideal equals the number of dissolved particles produced per formula unit under complete dissociation.

- Percent dissociation assumes ν > 1 and uses 100 × (i - 1) / (ν - 1).

- The association example assumes reversible dimerization only, with n = 2 and percent association = 100 × (1 - i) / (1 - 1/n).

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "solute": "NaCl",
    "behavior": "dissociation",
    "measured_delta_T": "1.50 K",
    "expected_nonelectrolyte_delta_T": "1.00 K",
    "ions_per_formula_unit": 2
  },
  "expected_outputs": {
    "i": 1.5,
    "i_ideal": 2,
    "percent_dissociation": 50,
    "percent_association": null
  },
  "working": "i = 1.50 / 1.00 = 1.50. For NaCl, ν = 2, so i_ideal = 2. Percent dissociation = 100 × (1.50 - 1) / (2 - 1) = 100 × 0.50 / 1 = 50%."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The zero expected nonelectrolyte temperature difference creates an undefined division, and an undocumented signed-versus-magnitude ΔT convention can produce a negative van't Hoff factor and nonsensical negative dissociation. The branch probe also requires explicit selection between association and dissociation formulas.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/van-t-hoff-factor-estimator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/van-t-hoff-factor-estimator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/van-t-hoff-factor-estimator/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`

- `BOUNDARY_HAZARD_CATALOG.json`