Ph Calc

{
  "asOf": "2026-10-11T08:45:40.750Z",
  "degraded": false,
  "description": "strongly acidic",
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "hydrogenIonMolar": 0.001332671,
  "hydroxideIonMolar": 7.5037276e-12,
  "method": "exact quadratic x^2 / (c - x) = Ka (no small-x approximation)",
  "mode": "weak-acid",
  "notChecked": [
    "activity coefficients (real solutions above about 0.1 M deviate from these ideal results)",
    "temperature (Kw = 1e-14 at 25 C only)",
    "…2 more"
  ],
  "pH": 2.8752771,
  "pOH": 11.124723,
  "percentIonised": 1.3327,
  "reasons": [
    "exact quadratic x^2 / (c - x) = Ka (no small-x approximation).",
    "Assumes 25 C (pH + pOH = 14) and ideal dilute solutions.",
    "…1 more"
  ],
  "source": "computed locally",
  "summary": "pH 2.875 (pOH 11.12), strongly acidic; [H+] = 1.333e-3 M, [OH-] = 7.504e-12 M.",
  "verdict": "ACIDIC"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://chemistry-calc.x402tookit.com/ph-calc?concentration=0.1&ka=0.000018&mode=weak-acid'

# 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/ph-calc?concentration=0.1&ka=0.000018&mode=weak-acid' \
  | 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%2Fph-calc
const res = await pay("https://chemistry-calc.x402tookit.com/ph-calc?concentration=0.1&ka=0.000018&mode=weak-acid");
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/ph-calc?concentration=0.1&ka=0.000018&mode=weak-acid")
    print(res.status_code, res.text)