# Chemistry Calculators – pH/pOH Calculator

> Chemistry Calculators – pH/pOH Calculator is a paid API for AI agents from chemistry-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Calculates pH, pOH, hydrogen-ion concentration, and related values for strong acids/bases, weak acids/bases, and buffers using Henderson-Hasselbalch.

## Facts

- Endpoint: GET https://chemistry-calc.x402tookit.com/ph-calc?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/chemistry-calculators-ph-poh-calculator-8a325648
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_iB9wQaGAgSOU1GPnTR3jc

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability chemistry-calculators-ph-poh-calculator-8a325648
```

Example prompt: What is the pH and pOH of a 0.05 M solution of acetic acid with a Ka of 1.8×10⁻⁵? Use the weak-acid mode.

## When to prefer this

Choose this endpoint when you need precise, formula-based acid-base pH/pOH calculations across all common chemistry scenarios — strong acids, strong bases, weak acids, weak bases, buffers, or pH/[H⁺] interconversions — and want a single API that handles all modes. Prefer it over general-purpose LLM math for accuracy and over building your own logic for breadth of coverage.

## Known failure modes

- Missing required 'mode' parameter returns an error
- Providing an invalid mode string returns a validation error
- Supplying concentration or Ka/Kb of zero or negative numbers may produce NaN or error responses
- Omitting Ka/Kb for weak-acid/weak-base mode causes calculation failure
- Omitting acidConc or baseConc for buffer mode causes failure
- Network or payment errors may prevent the call from completing

## How this service works

pH and pOH for a strong or weak acid or base, a hydrogen-ion concentration, or a buffer (Henderson-Hasselbalch).

## Output

Returns pH (numeric), pOH (numeric), hydrogen-ion molarity, hydroxide-ion molarity, percent ionized (for weak acids/bases), the mode used, a plain-language summary, and an optional disclaimer — all as a JSON object.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "mode"
     ],
     "properties": {
      "ka": {
       "type": "number",
       "description": "Acid dissociation constant (weak-acid, buffer uses pKa)"
      },
      "kb": {
       "type": "number",
       "description": "Base dissociation constant (weak-base)"
      },
      "pka": {
       "type": "number",
       "description": "pKa for a buffer"
      },
      "mode": {
       "type": "string",
       "description": "ph (convert a pH), h-conc, strong-acid, strong-base, weak-acid, weak-base or buffer"
      },
      "value": {
       "type": "number",
       "description": "pH value (mode ph) or hydrogen-ion molarity (mode h-conc)"
      },
      "protons": {
       "type": "integer",
       "description": "Ionisable H+ or OH- per formula unit for strong acids and bases (default 1)"
      },
      "acidConc": {
       "type": "number",
       "description": "Buffer weak-acid concentration (HA)"
      },
      "baseConc": {
       "type": "number",
       "description": "Buffer conjugate-base concentration (A-)"
      },
      "concentration": {
       "type": "number",
       "description": "Molarity of the acid or base"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "pH": {
       "type": [
        "null",
        "number"
       ]
      },
      "pOH": {
       "type": [
        "null",
        "number"
       ]
      },
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "mode": {
       "type": [
        "null",
        "string"
       ]
      },
      "method": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summ
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/chemistry-calculators-ph-poh-calculator-8a325648/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from chemistry-calc.x402tookit.com](https://www.zero.xyz/host/chemistry-calc.x402tookit.com/llms.txt)