{"uid":"cap_bhYYv43bAj3BdOEKL9Was","slug":"chem-openverbs-molar-mass-calculator-bba2d8cf","name":"Chem OpenVerbs Molar Mass Calculator","description":"Compute the molar mass (g/mol) of a chemical formula. Supports nested parentheses and brackets, element multipliers, and hydrate dot notation with coefficients (e.g. \"Ca(OH)2\", \"CuSO4·5H2O\", \"K4[Fe(CN)6]\"). Returns the total mass and the per-element composition with mass fraction percentages.","url":"https://chem.openverbs.com/v1/molar-mass","method":"POST","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method","bodyType","body"],"properties":{"body":{"type":"object","required":["formula"],"properties":{"formula":{"type":"string","maxLength":200,"minLength":1,"description":"Chemical formula, e.g. \"Ca(OH)2\"."}},"additionalProperties":false},"type":{"type":"string","const":"http"},"method":{"enum":["POST"],"type":"string"},"bodyType":{"enum":["json","form-data","text"],"type":"string"}},"additionalProperties":false}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.004","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.004/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.004","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.004","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_xD23COY5YSNQPrDHa0llw","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.004","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes the molar mass (g/mol) of a chemical formula, returning total mass and per-element composition with mass fraction percentages.","exampleAgentPrompt":"What's the molar mass of CuSO4·5H2O? I also want to see the mass fraction of each element.","exampleUseCases":[{"title":"Stoichiometry homework helper","prompt":"Can you calculate the molar mass of K4[Fe(CN)6] and tell me what percentage of the mass comes from each element?"},{"title":"Hydrate compound analysis","prompt":"I need the molar mass of MgSO4·7H2O and a breakdown of the mass fractions for magnesium, sulfur, oxygen, and hydrogen."},{"title":"Pharmaceutical compound check","prompt":"What is the molecular weight of Ca(OH)2 and how does each element contribute to the total mass?"}],"resultDescription":"Returns the total molar mass in g/mol along with a per-element breakdown showing each element's symbol, atomic count, individual molar contribution, and mass fraction as a percentage of the total.","failureModes":["Invalid or unrecognized element symbol in formula returns an error","Malformed parentheses or bracket nesting causes a parse error","Empty or missing formula field returns a validation error","Formula exceeding 200 characters is rejected","Unknown hydrate dot notation format may fail to parse"],"whenToPreferThis":"Choose this endpoint when you need precise molar mass computation with full elemental composition breakdown, especially for complex formulas with nested parentheses, brackets, or hydrate dot notation (e.g. CuSO4·5H2O). It is purpose-built for chemical formula parsing and handles edge cases that simple lookup tables miss.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T18:30:28.055Z","isFirstParty":false}