Graham's law calculator
This Graham's law calculator returns the relative rate of effusion of two gases from their molar masses.
Run — free
Graham's law states that the rate of effusion of a gas is inversely proportional to the square root of its molar mass, so the ratio of rates is rate one over rate two equals the square root of M two over M one. You supply positive molar masses M1 and M2 in consistent units, typically grams per mole, and the engine returns the dimensionless rate ratio, the inverse ratio, and the mass ratio M2 over M1. A familiar textbook check is hydrogen near 2.016 grams per mole against oxygen at 32 grams per mole, which yields a rate ratio of about four: hydrogen effuses roughly four times as fast as oxygen under the same conditions. Zero or negative molar mass is rejected because the square-root law is undefined for non-positive masses. The path is fully deterministic arithmetic with no network calls, no Monte Carlo sampling, and no date-dependent shortcuts. Use it free in the browser for gas-law homework, exam checks, and lab prep, or call the API at $0.002 per successful request when you need reproducible effusion-ratio fixtures in CI, tutoring software, or teaching demos.
How to use it
Enter your values in the form above. The tool checks them before calculating and shows the result on the same page.
Check your inputs
Use the labels and units shown next to each field. If something is missing or outside the allowed range, the page points to the field to fix.
Use it again or automate it
Use the browser tool for individual checks and the API when you need the same capability in an automated workflow.
What you can do with it
Get an answer now
Enter one set of values and see the result without building a spreadsheet or script.
Compare scenarios
Change one value at a time and rerun the calculation to understand what affects the result.
Automate repeated work
Use the API when the same calculation needs to run inside your product or workflow.
FAQ
How do I use this capability?
Complete the fields above and run it on this page. The form highlights anything that needs attention.
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/chem/rate-of-effusion \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"molar_mass_1":2.016,"molar_mass_2":32}'const res = await fetch("https://api.kit.forhosting.com/chem/rate-of-effusion", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"molar_mass_1": 2.016,
"molar_mass_2": 32
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/chem/rate-of-effusion",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"molar_mass_1": 2.016,
"molar_mass_2": 32
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/chem/rate-of-effusion", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"molar_mass_1":2.016,"molar_mass_2":32}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"molar_mass_1":2.016,"molar_mass_2":32}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/chem/rate-of-effusion", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"molar_mass_1": 2.016,
"molar_mass_2": 32
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "chem.rate_of_effusion",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_abs_value | 1000000000000000 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |