Limiting Reagent

{
  "asOf": "2026-10-11T08:45:39.716Z",
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "limitingReagent": "O2",
  "notChecked": [
    "whether the equation is balanced: the coefficients you give are used as stated",
    "side reactions, purity and reaction completeness (real yields are lower)",
    "…1 more"
  ],
  "percentYield": null,
  "product": "H2O",
  "reactants": [
    {
      "coefficient": 2,
      "gramsGiven": 4,
      "gramsLeft": 1.98387,
      "gramsUsed": 2.01613,
      "limiting": false,
      "molesGiven": 1.98413,
      "molesLeft": 0.984064,
      "molesUsed": 1.00006,
      "reactant": "H2",
      "reactionExtent": 0.992063
    },
    {
      "coefficient": 1,
      "gramsGiven": 16,
      "gramsLeft": 0,
      "gramsUsed": 16,
      "limiting": true,
      "molesGiven": 0.500031,
      "molesLeft": 0,
      "molesUsed": 0.500031,
      "reactant": "O2",
      "reactionExtent": 0.500031
    }
  ],
  "reasons": [
    "Compare moles divided by coefficient for each reactant: the smallest sets how far the reaction can go.",
    "The coefficients are used exactly as you give them: check the equation is balanced."
  ],
  "source": "computed locally",
  "summary": "O2 is limiting: theoretical yield 18.0161 g of H2O (1.00006 mol).",
  "theoreticalYieldGrams": 18.016126,
  "theoreticalYieldMoles": 1.0000625,
  "verdict": "LIMITING_REAGENT_FOUND"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://chemistry-calc.x402tookit.com/limiting-reagent?product=H2O%3A2&reactants=H2%3A2%3A4%3BO2%3A1%3A16'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://chemistry-calc.x402tookit.com/limiting-reagent?product=H2O%3A2&reactants=H2%3A2%3A4%3BO2%3A1%3A16' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fchemistry-calc.x402tookit.com%2Flimiting-reagent
const res = await pay("https://chemistry-calc.x402tookit.com/limiting-reagent?product=H2O%3A2&reactants=H2%3A2%3A4%3BO2%3A1%3A16");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://chemistry-calc.x402tookit.com/limiting-reagent?product=H2O%3A2&reactants=H2%3A2%3A4%3BO2%3A1%3A16")
    print(res.status_code, res.text)