Reaction Quotient (Q) vs Kc/Kp Comparator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-with-binding-errata

Evidence ID

t4-099

Effect

Computation or source lookup only

Input and validation requirements

A zero reactant concentration makes the Q denominator vanish, producing an undefined result that must be rejected. Direction labels are also ambiguous unless the reaction orientation used to define forward and reverse is explicitly documented.

Required corrections

[
  {
    "vector": 2,
    "field": "Q, delta_G",
    "wrong": "Q 0.01, dG -3.4346",
    "correct": "Q 0.0001, dG -14.8443 (direction still forward)",
    "cause": "Q computed with [NH3]=0.1 but input says 0.01"
  }
]

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "reaction": "N2 + 3 H2 ⇌ 2 NH3",
    "quotient_type": "Kc",
    "concentrations_mol_L": {
      "N2": 0.5,
      "H2": 0.8,
      "NH3": 0.2
    },
    "standard_concentration_mol_L": 1,
    "K": 0.04,
    "T_K": 298,
    "R_J_mol_K": 8.314
  },
  "expected_outputs": {
    "Q": 0.15625,
    "shift_direction": "reverse",
    "delta_G_kJ_mol": 3.3759
  },
  "working": "Q=(a_NH3^2)/(a_N2*a_H2^3)=(0.20/1.0)^2/[(0.50/1.0)*(0.80/1.0)^3]=0.0400/(0.50*0.512)=0.0400/0.256=0.15625. Since Q=0.15625>K=0.040, the shift is reverse. RT=(8.314*298)/1000=2.477572 kJ mol^-1. ΔG=-RT ln(K/Q)=-2.477572 ln(0.040/0.15625)=-2.477572 ln(0.256)=+3.3759 kJ mol^-1."
}

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
• tranche errata record