Source: https://guthlabs.ai/docs/instruments/van-t-hoff-factor-estimator/
instrument / verified-clean
# Van't Hoff Factor Estimator
The current ledger marks this instrument verified clean within the source-bound verification corpus.
Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**
## Inspectable records
[01**Overview**Purpose and lifecycle]()[02**Mechanism**Method and assumptions]()[03**Implementation**Binding and validation]()[04**Qualification**Evidence and errata]()
## Ledger state
The current ledger marks this instrument verified clean within the source-bound verification corpus.
**Area**: Chemistry & Materials
**Tranche**: tranche-4
**Evidence ID**: t4-195
**Ledger rows**: 1
No ledger note is attached.
## Review findings
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.
### Formula and scope findings
- 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.
### Unit assumptions
- 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).
## Boundary hardening
**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.
## 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": {
"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%."
}
````
## 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-tranche4/tranche4-results.json`
- `BOUNDARY_HAZARD_CATALOG.json`