Mole Fraction / Mole Percent Calculator mechanism

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

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