> ## Documentation Index > Fetch the complete documentation index at: https://docs.iotools.cloud/llms.txt > Use this file to discover all available pages before exploring further. # Limiting Reactant Calculator > Find the limiting reactant from a chemical equation and the amount of each reactant in grams or moles. Auto-balances the equation, then reports theoretical yield for every product, how much of each excess reactant is left over, and percent yield from your actual yield. [Try Limiting Reactant Calculator in your browser →](https://iotools.cloud/tool/limiting-reactant-calculator/) ## OpenAPI ````yaml https://api.iotools.cloud/v1/openapi post /v1/tool/limiting-reactant-calculator openapi: 3.1.0 info: title: iotools.cloud API version: 1.0.0 description: >- Run any iotools.cloud tool over HTTP. Authenticate with `Authorization: Bearer iot_live_…`. **Only `POST /v1/tool/{slug}` costs credits.** Every GET here — the catalog, a tool's schema, your balance — is free. A tool call is charged its own weight or your plan's per-call minimum, whichever is larger; `x-iotools-credit-cost` on each operation is quoted at the free-tier minimum, and `GET /v1/tools/list` returns the exact figure for your key. `GET /v1/me/credits` reports what you have left, and `GET /v1/me/usage` reports what it went on. Failures are RFC 9457 problem documents — branch on `code`. servers: - url: https://api.iotools.cloud description: Production security: - bearerAuth: [] tags: - name: Catalog description: Find a tool and read its contract. Free. - name: Converters description: >- Convert between formats, encodings, and units — Base64, CSV and JSON, timestamps, and more. Fast, free, and processed right in your browser. - name: Formatters description: >- Format, beautify, minify, and validate code and data — JSON, HTML, CSS, SQL, and regex. Clean up messy input in one click, with nothing to upload. - name: Generators description: >- Generate exactly what you need and on demand — passwords, UUIDs, QR codes, hashes, random numbers, and more. Secure, instant, and free. - name: Calculators description: >- Crunch the numbers fast — from everyday math to specialized conversions and unit work. Free online calculators that run entirely in your browser. - name: Editors description: >- Edit and transform text, code, and images with quick, focused editors that run entirely in your browser — nothing to install, and no sign-up needed. - name: Utilities description: >- Everyday developer and web utilities — DNS and IP lookups, redirect and certificate checkers, and other quick diagnostics. Free and privacy-friendly. - name: Account description: Your key's allowance, limits and usage history. paths: /v1/tool/limiting-reactant-calculator: post: tags: - Calculators summary: Limiting Reactant Calculator description: >- Find the limiting reactant from a chemical equation and the amount of each reactant in grams or moles. Auto-balances the equation, then reports theoretical yield for every product, how much of each excess reactant is left over, and percent yield from your actual yield. [Try Limiting Reactant Calculator in your browser →](https://iotools.cloud/tool/limiting-reactant-calculator/) operationId: run_limiting_reactant_calculator requestBody: required: true content: application/json: schema: type: object properties: equation: type: string description: Chemical Equation amounts: type: string description: Reactant Amounts unit: enum: - g - mol description: Amount Unit actualYield: type: number description: Actual Yield (g, optional) yieldProduct: type: number description: Product for Percent Yield minimum: 1 required: - equation - amounts examples: water_from_hydrogen_and_oxygen_grams_with_percent_yield: summary: Water from hydrogen and oxygen (grams, with percent yield) value: equation: H2 + O2 -> H2O amounts: 10, 64 unit: g actualYield: '65' yieldProduct: '1' iron_ore_reduction_fe2o3_co: summary: Iron ore reduction — Fe2O3 + CO value: equation: Fe2O3 + CO -> Fe + CO2 amounts: 100, 50 unit: g actualYield: '' yieldProduct: '1' propane_combustion_moles: summary: Propane combustion (moles) value: equation: C3H8 + O2 -> CO2 + H2O amounts: 1, 4 unit: mol actualYield: '' yieldProduct: '1' responses: '200': description: Tool output content: application/json: examples: water_from_hydrogen_and_oxygen_grams_with_percent_yield: summary: Water from hydrogen and oxygen (grams, with percent yield) value: tool: limiting-reactant-calculator tool_version: 1.0.2 outputs: balancedEquation: 2H2 + O2 → 2H2O limitingReactant: O2 reactantTable: - reactant: H2 coef: '2' molar-mass-g-mol: '2.016' moles-given: '4.96032' moles-coef: '2.48016' status: Excess left-over-mol: '0.960067' left-over-g: '1.9355' - reactant: O2 coef: '1' molar-mass-g-mol: '31.998' moles-given: '2.00013' moles-coef: '2.00013' status: Limiting left-over-mol: '0' left-over-g: '0' productTable: - product: H2O coef: '2' molar-mass-g-mol: '18.015' yield-mol: '4.00025' yield-g: '72.0645' percentYield: 90.197% of H2O (65 g of 72.0645 g) steps: >- 1. Balance: 2H2 + O2 → 2H2O (coefficients recalculated) 2. Convert each reactant to moles and divide by its coefficient: H2: 10 g ÷ 2.016 g/mol = 4.96032 mol ÷ 2 = 2.48016 O2: 64 g ÷ 31.998 g/mol = 2.00013 mol ÷ 1 = 2.00013 3. Smallest ratio → O2 is limiting (reaction extent 2.00013 mol). 4. Theoretical yield = extent × product coefficient × molar mass: H2O: 2.00013 × 2 × 18.015 = 72.0645 g credits_used: 5 credits_remaining: null iron_ore_reduction_fe2o3_co: summary: Iron ore reduction — Fe2O3 + CO value: tool: limiting-reactant-calculator tool_version: 1.0.2 outputs: balancedEquation: Fe2O3 + 3CO → 2Fe + 3CO2 limitingReactant: CO reactantTable: - reactant: Fe2O3 coef: '1' molar-mass-g-mol: '159.687' moles-given: '0.626225' moles-coef: '0.626225' status: Excess left-over-mol: '0.0311995' left-over-g: '4.98215' - reactant: CO coef: '3' molar-mass-g-mol: '28.01' moles-given: '1.78508' moles-coef: '0.595026' status: Limiting left-over-mol: '0' left-over-g: '0' productTable: - product: Fe coef: '2' molar-mass-g-mol: '55.845' yield-mol: '1.19005' yield-g: '66.4584' - product: CO2 coef: '3' molar-mass-g-mol: '44.009' yield-mol: '1.78508' yield-g: '78.5594' percentYield: '' steps: >- 1. Balance: Fe2O3 + 3CO → 2Fe + 3CO2 (coefficients recalculated) 2. Convert each reactant to moles and divide by its coefficient: Fe2O3: 100 g ÷ 159.687 g/mol = 0.626225 mol ÷ 1 = 0.626225 CO: 50 g ÷ 28.01 g/mol = 1.78508 mol ÷ 3 = 0.595026 3. Smallest ratio → CO is limiting (reaction extent 0.595026 mol). 4. Theoretical yield = extent × product coefficient × molar mass: Fe: 0.595026 × 2 × 55.845 = 66.4584 g CO2: 0.595026 × 3 × 44.009 = 78.5594 g credits_used: 5 credits_remaining: null propane_combustion_moles: summary: Propane combustion (moles) value: tool: limiting-reactant-calculator tool_version: 1.0.2 outputs: balancedEquation: C3H8 + 5O2 → 3CO2 + 4H2O limitingReactant: O2 reactantTable: - reactant: C3H8 coef: '1' molar-mass-g-mol: '44.097' moles-given: '1' moles-coef: '1' status: Excess left-over-mol: '0.2' left-over-g: '8.8194' - reactant: O2 coef: '5' molar-mass-g-mol: '31.998' moles-given: '4' moles-coef: '0.8' status: Limiting left-over-mol: '0' left-over-g: '0' productTable: - product: CO2 coef: '3' molar-mass-g-mol: '44.009' yield-mol: '2.4' yield-g: '105.622' - product: H2O coef: '4' molar-mass-g-mol: '18.015' yield-mol: '3.2' yield-g: '57.648' percentYield: '' steps: >- 1. Balance: C3H8 + 5O2 → 3CO2 + 4H2O (coefficients recalculated) 2. Convert each reactant to moles and divide by its coefficient: C3H8: 1 mol ÷ 1 = 1 O2: 4 mol ÷ 5 = 0.8 3. Smallest ratio → O2 is limiting (reaction extent 0.8 mol). 4. Theoretical yield = extent × product coefficient × molar mass: CO2: 0.8 × 3 × 44.009 = 105.622 g H2O: 0.8 × 4 × 18.015 = 57.648 g credits_used: 5 credits_remaining: null schema: type: object required: - tool - tool_version - outputs - credits_used - credits_remaining properties: outputs: type: object properties: balancedEquation: type: string description: Balanced Equation limitingReactant: type: string description: Limiting Reactant reactantTable: type: array description: Reactants items: type: object properties: reactant: type: string description: Reactant coef: type: string description: Coef. molar-mass-g-mol: type: string description: Molar Mass (g/mol) moles-given: type: string description: Moles Given moles-coef: type: string description: Moles ÷ Coef. status: type: string description: Status left-over-mol: type: string description: Left Over (mol) left-over-g: type: string description: Left Over (g) x-iotools-columns: - reactant - coef - molar-mass-g-mol - moles-given - moles-coef - status - left-over-mol - left-over-g productTable: type: array description: Theoretical Yield items: type: object properties: product: type: string description: Product coef: type: string description: Coef. molar-mass-g-mol: type: string description: Molar Mass (g/mol) yield-mol: type: string description: Yield (mol) yield-g: type: string description: Yield (g) x-iotools-columns: - product - coef - molar-mass-g-mol - yield-mol - yield-g percentYield: type: string description: Percent Yield steps: type: string description: Steps tool: type: string description: The tool's slug, echoing the {slug} in the request path. tool_version: type: string description: Output-contract version for this tool. credits_used: type: integer description: >- Credits this call consumed, after any settlement refund. 0 when metering is disabled. credits_remaining: type: - integer - 'null' description: >- Credits left in the current monthly allowance, or null when metering is disabled. request_id: type: string description: Correlation id, also sent as x-request-id. '400': $ref: '#/components/responses/ValidationError' '401': $ref: '#/components/responses/Unauthorized' '402': $ref: '#/components/responses/InsufficientCredits' '403': $ref: '#/components/responses/ToolNotAllowed' '404': $ref: '#/components/responses/ToolNotFound' '413': $ref: '#/components/responses/PayloadTooLarge' '422': $ref: '#/components/responses/UnprocessableInput' '429': $ref: '#/components/responses/RateLimited' '500': $ref: '#/components/responses/ToolFailed' '503': $ref: '#/components/responses/ToolDisabled' security: - bearerAuth: [] components: responses: ValidationError: description: Invalid request. content: application/problem+json: schema: type: object description: >- RFC 9457 problem document, served as application/problem+json. Branch on `code`; `title` is human prose and may be reworded without notice. Some failures add extension members — `fields` on validation errors, `retry_after` on 429s, `credits_used`/`credits_remaining` on billing-adjacent failures — documented on the responses that carry them. required: - type - title - status - code properties: type: type: string format: uri description: Stable documentation URI for this failure. examples: - https://docs.iotools.cloud/errors/validation_error title: type: string description: Short human-readable summary of the failure. examples: - Invalid request status: type: integer description: HTTP status code, matching the response's own status. code: type: string description: >- Stable machine-readable error code — branch on this, not `title`. enum: - validation_error detail: type: string description: Human explanation of this occurrence. request_id: type: string description: Correlation id, also sent as x-request-id. fields: type: - object - string additionalProperties: type: string description: >- What failed: a map of field name → message. Absent when the body itself is malformed; a single string when the failure isn't tied to one field. example: type: https://docs.iotools.cloud/errors/validation_error title: Invalid request status: 400 code: validation_error detail: One or more inputs are invalid — see `fields`. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 fields: inputString: Required Unauthorized: description: Missing or invalid API key. content: application/problem+json: schema: type: object description: >- RFC 9457 problem document, served as application/problem+json. Branch on `code`; `title` is human prose and may be reworded without notice. Some failures add extension members — `fields` on validation errors, `retry_after` on 429s, `credits_used`/`credits_remaining` on billing-adjacent failures — documented on the responses that carry them. required: - type - title - status - code properties: type: type: string format: uri description: Stable documentation URI for this failure. examples: - https://docs.iotools.cloud/errors/invalid_api_key title: type: string description: Short human-readable summary of the failure. examples: - Invalid API key status: type: integer description: HTTP status code, matching the response's own status. code: type: string description: >- Stable machine-readable error code — branch on this, not `title`. enum: - invalid_api_key detail: type: string description: Human explanation of this occurrence. request_id: type: string description: Correlation id, also sent as x-request-id. example: type: https://docs.iotools.cloud/errors/invalid_api_key title: Invalid API key status: 401 code: invalid_api_key detail: 'Provide ''Authorization: Bearer ''.' request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 InsufficientCredits: description: Monthly credit allowance exhausted. content: application/problem+json: schema: type: object description: >- RFC 9457 problem document, served as application/problem+json. Branch on `code`; `title` is human prose and may be reworded without notice. Some failures add extension members — `fields` on validation errors, `retry_after` on 429s, `credits_used`/`credits_remaining` on billing-adjacent failures — documented on the responses that carry them. required: - type - title - status - code properties: type: type: string format: uri description: Stable documentation URI for this failure. examples: - https://docs.iotools.cloud/errors/insufficient_credits - >- https://docs.iotools.cloud/errors/vendor_api_tier_limit_exceeded title: type: string description: Short human-readable summary of the failure. examples: - Insufficient credits - Free-tier API limit reached for this tool status: type: integer description: HTTP status code, matching the response's own status. code: type: string description: >- Stable machine-readable error code — branch on this, not `title`. enum: - insufficient_credits - vendor_api_tier_limit_exceeded detail: type: string description: Human explanation of this occurrence. request_id: type: string description: Correlation id, also sent as x-request-id. credits_used: type: integer description: Always 0 — a refused call charges nothing. credits_remaining: type: integer description: Credits left in the allowance — fewer than this call costs. example: type: https://docs.iotools.cloud/errors/insufficient_credits title: Insufficient credits status: 402 code: insufficient_credits detail: This call costs 1 credit and 0 remain in this month's allowance. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 credits_used: 0 credits_remaining: 0 ToolNotAllowed: description: Tool exists but has no API surface. content: application/problem+json: schema: type: object description: >- RFC 9457 problem document, served as application/problem+json. Branch on `code`; `title` is human prose and may be reworded without notice. Some failures add extension members — `fields` on validation errors, `retry_after` on 429s, `credits_used`/`credits_remaining` on billing-adjacent failures — documented on the responses that carry them. required: - type - title - status - code properties: type: type: string format: uri description: Stable documentation URI for this failure. examples: - https://docs.iotools.cloud/errors/tool_not_allowed title: type: string description: Short human-readable summary of the failure. examples: - Tool not available over the API status: type: integer description: HTTP status code, matching the response's own status. code: type: string description: >- Stable machine-readable error code — branch on this, not `title`. enum: - tool_not_allowed detail: type: string description: Human explanation of this occurrence. request_id: type: string description: Correlation id, also sent as x-request-id. example: type: https://docs.iotools.cloud/errors/tool_not_allowed title: Tool not available over the API status: 403 code: tool_not_allowed detail: >- "Background Remover" is available on iotools.cloud but has no API endpoint. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 ToolNotFound: description: No such tool. content: application/problem+json: schema: type: object description: >- RFC 9457 problem document, served as application/problem+json. Branch on `code`; `title` is human prose and may be reworded without notice. Some failures add extension members — `fields` on validation errors, `retry_after` on 429s, `credits_used`/`credits_remaining` on billing-adjacent failures — documented on the responses that carry them. required: - type - title - status - code properties: type: type: string format: uri description: Stable documentation URI for this failure. examples: - https://docs.iotools.cloud/errors/tool_not_found title: type: string description: Short human-readable summary of the failure. examples: - Tool not found status: type: integer description: HTTP status code, matching the response's own status. code: type: string description: >- Stable machine-readable error code — branch on this, not `title`. enum: - tool_not_found detail: type: string description: Human explanation of this occurrence. request_id: type: string description: Correlation id, also sent as x-request-id. example: type: https://docs.iotools.cloud/errors/tool_not_found title: Tool not found status: 404 code: tool_not_found detail: No tool with that slug. See GET /v1/tools/list. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 PayloadTooLarge: description: Body too large. content: application/problem+json: schema: type: object description: >- RFC 9457 problem document, served as application/problem+json. Branch on `code`; `title` is human prose and may be reworded without notice. Some failures add extension members — `fields` on validation errors, `retry_after` on 429s, `credits_used`/`credits_remaining` on billing-adjacent failures — documented on the responses that carry them. required: - type - title - status - code properties: type: type: string format: uri description: Stable documentation URI for this failure. examples: - https://docs.iotools.cloud/errors/payload_too_large title: type: string description: Short human-readable summary of the failure. examples: - Payload too large status: type: integer description: HTTP status code, matching the response's own status. code: type: string description: >- Stable machine-readable error code — branch on this, not `title`. enum: - payload_too_large detail: type: string description: Human explanation of this occurrence. request_id: type: string description: Correlation id, also sent as x-request-id. example: type: https://docs.iotools.cloud/errors/payload_too_large title: Payload too large status: 413 code: payload_too_large detail: Request body exceeds this tool's size limit. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 UnprocessableInput: description: Well-formed request, but there is no result to return. content: application/problem+json: schema: type: object description: >- RFC 9457 problem document, served as application/problem+json. Branch on `code`; `title` is human prose and may be reworded without notice. Some failures add extension members — `fields` on validation errors, `retry_after` on 429s, `credits_used`/`credits_remaining` on billing-adjacent failures — documented on the responses that carry them. required: - type - title - status - code properties: type: type: string format: uri description: Stable documentation URI for this failure. examples: - https://docs.iotools.cloud/errors/unprocessable_input title: type: string description: Short human-readable summary of the failure. examples: - Input cannot be processed status: type: integer description: HTTP status code, matching the response's own status. code: type: string description: >- Stable machine-readable error code — branch on this, not `title`. enum: - unprocessable_input detail: type: string description: Human explanation of this occurrence. request_id: type: string description: Correlation id, also sent as x-request-id. credits_used: type: integer description: >- Always 0 on `unprocessable_input` — a failed run is refunded, floor included. credits_remaining: type: integer description: >- Credits left after the refund. Absent when metering is disabled. example: type: https://docs.iotools.cloud/errors/unprocessable_input title: Input cannot be processed status: 422 code: unprocessable_input detail: >- This video has no captions or subtitles, so there is no transcript to extract. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 credits_used: 0 RateLimited: description: Per-minute rate limit exceeded. headers: Retry-After: description: Seconds to wait before retrying (RFC 9110 delta-seconds). schema: type: integer content: application/problem+json: schema: type: object description: >- RFC 9457 problem document, served as application/problem+json. Branch on `code`; `title` is human prose and may be reworded without notice. Some failures add extension members — `fields` on validation errors, `retry_after` on 429s, `credits_used`/`credits_remaining` on billing-adjacent failures — documented on the responses that carry them. required: - type - title - status - code properties: type: type: string format: uri description: Stable documentation URI for this failure. examples: - https://docs.iotools.cloud/errors/rate_limited title: type: string description: Short human-readable summary of the failure. examples: - Rate limit exceeded status: type: integer description: HTTP status code, matching the response's own status. code: type: string description: >- Stable machine-readable error code — branch on this, not `title`. enum: - rate_limited detail: type: string description: Human explanation of this occurrence. request_id: type: string description: Correlation id, also sent as x-request-id. retry_after: type: integer description: >- Seconds until the window resets — the same value as the `Retry-After` header. example: type: https://docs.iotools.cloud/errors/rate_limited title: Rate limit exceeded status: 429 code: rate_limited detail: Too many requests. Retry in 30s. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 retry_after: 30 ToolFailed: description: Tool failed to run. content: application/problem+json: schema: type: object description: >- RFC 9457 problem document, served as application/problem+json. Branch on `code`; `title` is human prose and may be reworded without notice. Some failures add extension members — `fields` on validation errors, `retry_after` on 429s, `credits_used`/`credits_remaining` on billing-adjacent failures — documented on the responses that carry them. required: - type - title - status - code properties: type: type: string format: uri description: Stable documentation URI for this failure. examples: - https://docs.iotools.cloud/errors/processing_error - https://docs.iotools.cloud/errors/internal_error title: type: string description: Short human-readable summary of the failure. examples: - Tool failed to run - Internal error status: type: integer description: HTTP status code, matching the response's own status. code: type: string description: >- Stable machine-readable error code — branch on this, not `title`. enum: - processing_error - internal_error detail: type: string description: Human explanation of this occurrence. request_id: type: string description: Correlation id, also sent as x-request-id. credits_used: type: integer description: >- Always 0 on `processing_error` — a failed run is refunded, floor included. credits_remaining: type: integer description: >- Credits left after the refund. Absent when metering is disabled. example: type: https://docs.iotools.cloud/errors/processing_error title: Tool failed to run status: 500 code: processing_error detail: The tool failed to run. Please try again. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 credits_used: 0 ToolDisabled: description: Tool temporarily disabled. content: application/problem+json: schema: type: object description: >- RFC 9457 problem document, served as application/problem+json. Branch on `code`; `title` is human prose and may be reworded without notice. Some failures add extension members — `fields` on validation errors, `retry_after` on 429s, `credits_used`/`credits_remaining` on billing-adjacent failures — documented on the responses that carry them. required: - type - title - status - code properties: type: type: string format: uri description: Stable documentation URI for this failure. examples: - https://docs.iotools.cloud/errors/tool_disabled - https://docs.iotools.cloud/errors/api_unconfigured title: type: string description: Short human-readable summary of the failure. examples: - Tool temporarily disabled - API not configured status: type: integer description: HTTP status code, matching the response's own status. code: type: string description: >- Stable machine-readable error code — branch on this, not `title`. enum: - tool_disabled - api_unconfigured detail: type: string description: Human explanation of this occurrence. request_id: type: string description: Correlation id, also sent as x-request-id. example: type: https://docs.iotools.cloud/errors/tool_disabled title: Tool temporarily disabled status: 503 code: tool_disabled detail: This tool is temporarily unavailable. Try again shortly. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: iot_live_… ````