Molarity / Solution Prep Calculator mechanism

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

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