Discover / chem.openverbs.com

Molar mass

■ Challenge detected

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.

x402
Base
USDC

Listed price: $0.004
Challenge detected: 9 of the last 9 checks
Median response: 184 ms
Last checked: 16 Oct, 23:40 UTC
In our index since: 26 Sept 2026

Endpoint

curl -i https://chem.openverbs.com/v1/molar-mass
# 402 Payment Required: pay with an x402 client (USDC on Base),
# then send the same request again with the payment attached.

3 listed endpoints · on x402 Bazaar

Checks and payment terms on this page refer to the endpoint above. Other listed endpoints have not been checked individually.

Base URLhttps://chem.openverbs.com/v1

POST/search$0.004Search the periodic table by name or symbol substring. Exact matches rank first, then prefix matches, then substring matches. Returns up to `limit` elements (default 20) plus the total match count.
POST/element$0.004Look up a periodic-table element by exactly one of `symbol` (e.g. "Fe"), `name` (e.g. "iron") or atomic `number` (1..118). Returns its number, symbol, name, standard atomic weight and whether that weight is a true standard atomic weight.
POST/molar-mass$0.004Compute 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.

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Showing 3 of 3 listed endpoints.

Agents can find it through the Superstables MCP server and JSON API: GET /api/v1/services/chem.openverbs.com

Recent checks

4 Oct 2026One bar per check, showing up to 20 recent checks. Coloured bars show relative response time, with a minimum visible height; full-height grey bars mean no challenge was detected. “Challenge detected” means HTTP 402 or another detected payment-challenge signal.16 Oct 2026

All 9 checks

When (UTC)	Result	HTTP	Response
16 Oct, 23:40 UTC	Challenge detected	402	188ms
15 Oct, 19:10 UTC	Challenge detected	402	213ms
14 Oct, 14:31 UTC	Challenge detected	402	179ms
12 Oct, 10:53 UTC	Challenge detected	402	488ms
10 Oct, 15:44 UTC	Challenge detected	402	184ms
9 Oct, 09:34 UTC	Challenge detected	402	224ms
8 Oct, 06:42 UTC	Challenge detected	402	160ms
7 Oct, 03:32 UTC	Challenge detected	402	176ms
4 Oct, 05:04 UTC	Challenge detected	402	173ms

Questions

Did our last probe detect a payment challenge?

At our last probe on 16 Oct, 23:40 UTC, it returned HTTP 402 or another detected payment-challenge signal. This check did not test payment, delivery or compatibility with the Superstables client.

What price is recorded for Molar mass?

Its listed price is $0.004.

What payment terms does Molar mass advertise?

The listing advertises x402, Base and USDC. It names cdp as its facilitator. Check the seller's current payment challenge and authentication requirements before paying.

Where is Molar mass listed?

In x402 Bazaar. Superstables first indexed it on 26 Sept 2026.

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