Source: https://guthlabs.ai/docs/instruments/molarity-solution-prep-calculator/mechanism/

instrument mechanism / verified-clean

# Molarity / Solution Prep Calculator mechanism

The inspectable method record for Molarity / Solution Prep Calculator, kept separate from implementation and qualification.

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

## Model scope

The molarity mass formula is standard under the stated unit assumptions. The specification needs explicit %w/v formulas, an explicit stock-dilution formula, and validation rules before implementation. The existing lab-planning and verify-against-protocol labeling is appropriate but should remain visible on every calculation panel.

- mass = M × V × MW is correct only when M is in mol/L, V is in final solution liters, and MW is in g/mol.

- “%w/v conversions” is underspecified: %w/v must be explicitly defined as grams of solute per 100 mL of final solution, with formulas provided for conversion to mass and, if supported, molarity.

- The claimed output “mL of stock” requires the dilution formula C1V1 = C2V2, which is not specified.

- The specification does not state whether the entered volume is final solution volume or solvent volume; preparation calculations normally use final solution volume.

- Required constraints are not specified for positive molecular weight, nonnegative target concentration, positive final volume, and nonzero stock concentration.

## Units and conventions

- For mass = M × V × MW: M is mol/L, V is liters of final solution, MW is g/mol, and the output is grams.

- For %w/v: x% means x grams of solute per 100 mL of final solution.

- For %w/v mass: mass in grams = (%w/v × final volume in mL) / 100.

- For %w/v to molarity, if supported: M = (10 × %w/v) / MW, where MW is in g/mol.

- For stock dilution: C1 and C2 must use the same concentration units, volumes must use the same volume units, and V1 = C2 × V2 / C1.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "target_molarity_M": 0.15,
    "final_volume_L": 0.5,
    "molecular_weight_g_per_mol": 58.44
  },
  "expected_outputs": {
    "mass_g": 4.383
  },
  "working": "Moles = 0.15 mol/L × 0.500 L = 0.0750 mol. Mass = 0.0750 mol × 58.44 g/mol = 4.383 g."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The specification permits a zero-concentration stock input that produces an undefined stock-volume division, and its mixed L/mL and %w/v workflows can produce a factor-of-1000 or formula-mode error unless units and concentration mode are explicitly enforced.

## Other records

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