# Chemistry Calculators – Limiting Reagent & Theoretical Yield

> Chemistry Calculators – Limiting Reagent & Theoretical Yield 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 the limiting reagent, theoretical yield, and excess leftover for each reactant in a balanced chemical reaction given reactant masses; optionally computes percent yield.

## Facts

- Endpoint: GET https://chemistry-calc.x402tookit.com/limiting-reagent?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-limiting-reagent-theoretical-yield-5566f474
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ALzsOh8txsOnQ3FVdYR3r

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-limiting-reagent-theoretical-yield-5566f474
```

Example prompt: For the reaction 2 H2 + O2 → 2 H2O, I have 4 grams of H2 and 16 grams of O2 — which is the limiting reagent, what's the theoretical yield of water in grams, and how much of the excess reagent is left over?

## When to prefer this

Use this endpoint when you need to perform stoichiometric analysis on a balanced chemical reaction — specifically to identify the limiting reagent, compute theoretical yield, quantify excess reagents, or calculate percent yield from experimental data. It is purpose-built for chemistry stoichiometry and handles multi-reactant reactions with molar mass lookups internally, making it far more convenient than doing manual mol calculations. Prefer it over generic math or formula solvers whenever the context involves a chemical equation with known reactant masses.

## Known failure modes

- Missing or malformed reactants/product query parameters returns an error
- Unrecognized chemical formula (e.g. typo in element symbol) causes a parse failure
- Stoichiometrically unbalanced equation may produce incorrect or flagged results
- Zero or negative gram values may cause computation errors
- actualGrams provided without valid reactants/product will still fail if core params are missing

## How this service works

Limiting reagent, theoretical yield and leftover excess for a balanced reaction from reactant masses; optional percent yield.

## Output

Returns a structured object identifying the limiting reagent by formula, the theoretical yield of the specified product in both grams and moles, and per-reactant details including grams given, grams used, grams left over, moles given, moles used, moles left over, stoichiometric coefficient, and reaction extent. If actual product mass is supplied, percent yield is also returned. A human-readable summary and list of reasoning steps are included.

## 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": [
      "reactants",
      "product"
     ],
     "properties": {
      "product": {
       "type": "string",
       "description": "formula:coefficient of the product, e.g. H2O:2"
      },
      "reactants": {
       "type": "string",
       "description": "formula:coefficient:grams separated by semicolons, e.g. H2:2:4;O2:1:16"
      },
      "actualGrams": {
       "type": "number",
       "description": "Actual product mass obtained, to compute percent yield"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "product": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "reactants": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "object",
        "properties": {
         "limiting": {
          "type": [
           "boolean",
           "null"
          ]
         },
         "reactant": {
          "type": [
           "null",
           "string"
          ]
         },
         "gramsLeft": {
          "type": [
           "null",
           "number"
          ]
         },
         "gramsUsed": {
          "type": [
           "null",
           "number"
          ]
         },
         "molesLeft": {
          "type": [
           "null",
           "number"
          ]
         },
 
… (truncated)
```

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