Source: https://guthlabs.ai/docs/instruments/graham-s-law-effusion-diffusion-calculator/
instrument / verified-clean
# Graham's Law Effusion/Diffusion Calculator
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**: t4-171
**Ledger rows**: 1
No ledger note is attached.
## Review findings
NEEDS_REVIEW because the exact ambiguity is that the spec does not identify which rate or time is known, does not state the equal-quantity assumption for time calculations, and uses diffusion as though Graham's effusion relationship were universally exact. The instrument should honestly label the result as a Graham-law estimate for effusion and an approximation for diffusion, and should document the atomic-weight table and unit-normalization rules.
### Formula and scope findings
- rate1/rate2 = sqrt(M2/M1) is the standard Graham-law relationship for effusion when rates are measured under comparable conditions and molar masses use the same units.
- For diffusion, the relationship is an approximation and may not apply exactly when gases have different intermolecular interactions, concentrations, pressures, or transport conditions; labeling the result simply as a diffusion rate may be misleading.
- The specification does not explicitly provide the time relationship needed for time outputs: for equal amounts of gas, t1/t2 = sqrt(M1/M2), equivalently t2 = t1*sqrt(M2/M1).
- The inputs do not specify which rate or time is known, so the direction of the calculation is ambiguous.
### Unit assumptions
- M1 and M2 are molar masses in the same units, conventionally g/mol; any parsed chemical formulas must use a defined atomic-weights table and a stated rounding convention.
- Rate1 and rate2 must use the same rate units before applying the ratio; unit conversion is not supplied by Graham's law itself.
- Times must use the same time units, and the time relationship assumes equal quantities of gas are being compared.
- The gases are compared under sufficiently similar temperature, pressure, and apparatus conditions.
- Formula-derived molar masses assume neutral molecular formulas and require unambiguous formula parsing.
## Boundary hardening
**BREAK_CLAIMED** · SELF_FLAGGED
The specification permits an input with zero molar mass even though it makes the square-root argument undefined, so the calculator requires explicit domain rejection. It also leaves the direction of the reported rate ratio dependent on gas labeling, creating a convention hazard.
## 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": {
"gas1": "H2",
"M1_g_per_mol": 2,
"gas2": "O2",
"M2_g_per_mol": 32,
"known_rate1_L_per_s": 8,
"known_time1_s": 10
},
"expected_outputs": {
"rate_ratio_rate1_over_rate2": 4,
"rate2_L_per_s": 2,
"time2_s": 40
},
"working": "M2/M1 = 32/2 = 16; sqrt(16) = 4, so rate1/rate2 = 4. rate2 = rate1/4 = 8/4 = 2 L/s. For equal gas quantities, t2 = t1*sqrt(M2/M1) = 10*4 = 40 s."
}
````
## 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`