Math & Numbers

Molar Mass Lookup

Look up the molar mass (atomic weight) of several elements at once by symbol, atomic number, or name, as a sortable comparison table.

json· JSON resultOpen tool

Quick start

Call this tool from your code in three languages.

cURL

curl -X POST 'https://api.elysiatools.com/en/api/tools/molar-mass-lookup' \
  -H 'Content-Type: application/json' \
  -d '{"elements":"Fe, Cu, Zn","sortBy":"input-order","includeDetails":false,"decimalPlaces":4}'

API reference

Send a POST request with your inputs as JSON. File parameters require a separate upload first.

Endpoint

HTTP

POST https://api.elysiatools.com/en/api/tools/molar-mass-lookup

Parameters

Name	Type	Required	Description
elements	textarea	Yes	Each token may be an element symbol (Fe), an atomic number (26), or an English element name (iron). Separators: comma, space, semicolon, or new line.
sortBy	select	No	—
includeDetails	checkbox	No	When on, each row also carries category, standard state, electronegativity, melting/boiling point, density, etc.
decimalPlaces	number	No	—

Response format

JSON result

MCP integration

Add this tool to your Model Context Protocol server so AI agents can list and call it.

Server configuration

Add this block to your MCP client configuration:

mcp.json

{
  "mcpServers": {
    "elysiatools-molar-mass-lookup": {
      "name": "molar-mass-lookup",
      "description": "Look up the molar mass (atomic weight) of several elements at once by symbol, atomic number, or name, as a sortable comparison table.",
      "baseUrl": "https://api.elysiatools.com/mcp/sse?toolId=molar-mass-lookup",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

List available tools

After connecting to the SSE endpoint, list the exposed tools:

tools/list

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/list"
}

Call this tool

Invoke the tool by its id, passing arguments built from its parameters:

tools/call

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "molar-mass-lookup",
    "arguments": {
  "elements": "Fe, Cu, Zn",
  "sortBy": "input-order",
  "includeDetails": false,
  "decimalPlaces": 4
}
  }
}

Chain multiple tools in one session with a comma-separated toolId list, e.g. /mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp (max 20).

Questions or issues? Contact [email protected]

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