Source: https://guthlabs.ai/docs/instruments/mole-fraction-mole-percent-calculator/mechanism/

instrument mechanism / verified-clean

# Mole Fraction / Mole Percent Calculator mechanism

The inspectable method record for Mole Fraction / Mole Percent Calculator, kept separate from implementation and qualification.

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

## Model scope

The core mole-fraction formula is correct. Review is required to define the mass+M input schema, supported units, whether direct moles and mass-based components can be mixed, validation behavior, and whether mole percent is also an output. The instrument should honestly label xᵢ as dimensionless mole fraction and should state that Σx = 1 only for a complete component list and a positive total amount.

- xᵢ = nᵢ/Σn is the standard mole-fraction formula when every nᵢ is an amount in moles. The stated alternative input 'mass+M' is underspecified because the required conversion nᵢ = mᵢ/Mᵢ is not included.

- The specification does not state whether mass and molar mass must be supplied for every component or may be mixed with direct mole inputs.

## Units and conventions

- All nᵢ values must be in moles before applying xᵢ = nᵢ/Σn.

- For mass inputs, mᵢ and Mᵢ must use compatible units, such as grams and grams per mole or kilograms and kilograms per mole.

- Molar masses must be positive; component amounts must be nonnegative.

- The total amount Σn must be greater than zero.

- Mole percent, if displayed, is 100xᵢ and should not be confused with the dimensionless mole fraction.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "mode": "moles",
    "components": {
      "ethanol": 2,
      "water": 8
    }
  },
  "expected_outputs": {
    "x_ethanol": 0.2,
    "x_water": 0.8,
    "sum_x": 1
  },
  "working": "1. Sum the amounts: Σn = 2.0 mol + 8.0 mol = 10.0 mol. 2. Ethanol: x = 2.0/10.0 = 0.2. 3. Water: x = 8.0/10.0 = 0.8. 4. Check: Σx = 0.2 + 0.8 = 1.0."
}
````

## Failure boundary

- If all component amounts are zero, Σn = 0 and every mole fraction requires division by zero; the calculator must reject this input.

- Negative amounts are physically invalid and must be rejected.

- A zero molar mass causes division by zero in mass-to-mole conversion and must be rejected.

- Incompatible mass and molar-mass units produce incorrect results unless converted first.

- Floating-point rounding can make the displayed Σx differ slightly from 1; the check should use a documented tolerance.

## Other records

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