Source: https://guthlabs.ai/docs/instruments/nernst-equation-calculator/mechanism/

instrument mechanism / verified-clean

# Nernst Equation Calculator mechanism

The inspectable method record for Nernst Equation Calculator, kept separate from implementation and qualification.

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

## Model scope

The instrument should not be honestly labeled as computing E from arbitrary ion concentrations until it requires or defines the balanced cell reaction, stoichiometric exponents, activities or an ideal concentration approximation, and reaction orientation. It should also distinguish the exact temperature-dependent RT/nF form from the approximate 25 °C 0.0592 form. The CODATA R version and the chosen F precision should be fixed for reproducible results.

- The algebraic Nernst formulas are standard and correct, but 'Q or ion concentrations' is ambiguous because the reaction stoichiometry and the mapping from concentrations to Q are not specified.

- Q must be the dimensionless reaction quotient formed from activities (or concentration ratios under an explicitly stated ideal-solution approximation); raw concentrations cannot universally be substituted directly.

- The 0.0592 coefficient is an approximation valid for base-10 logarithms at 25 °C (298.15 K), not at an arbitrary temperature.

- The sign and definition of Q depend on the specified cell-reaction orientation, which is not provided.

## Units and conventions

- E° and E are in volts.

- n is a positive, dimensionless electron-transfer count.

- T in E=E°-(RT/nF)ln Q is absolute temperature in kelvins; Celsius must be converted using T_K=T_°C+273.15.

- R is 8.314462618 J mol^-1 K^-1 and F is 96485 C mol^-1 for the test calculations.

- Q is dimensionless and is constructed from activities relative to the standard state.

- The 0.0592/n coefficient uses log base 10 and assumes T=298.15 K; the more precise value is approximately 0.05916 V per electron.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "E°_V": 1.1,
    "n": 2,
    "Q": 0.01,
    "T_K": 298.15,
    "formula": "E=E°-(RT/nF)ln Q"
  },
  "expected_outputs": {
    "E_V": 1.15916
  },
  "working": "R T/F = (8.314462618 J mol^-1 K^-1 × 298.15 K)/(96485 C mol^-1) = 0.02569267 V. Therefore RT/(nF)=0.02569267/2=0.01284633 V. ln(0.01)=-4.60517019. E=1.10-(0.01284633×-4.60517019)=1.10+0.05915955=1.15915955 V, approximately 1.15916 V."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The input n=0 produces division by zero in the Nernst correction term, so the calculator must reject it rather than return a numeric potential. The specification does not state an explicit validation rule for this case.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/nernst-equation-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/nernst-equation-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/nernst-equation-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`

- `BOUNDARY_HAZARD_CATALOG.json`