Solution boiling point calculator
Water that boils at 100 °C, with Kb of 0.512 and a 0.5 mol/kg solute, boils at 100.256 °C as a solution. Enter the solvent's boiling point, molality, Kb and particle factor to get the full boiling temperature, not only the rise. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Solvent bp
- 100
- Molality
- 0.5
- Kb
- 0.512
- Current (A)
- 1
- Delta tb
- 0.256
- Boiling point
- 100.256
- Precision
- 10
This solution boiling point calculator returns the colligative boiling temperature Tb of a dilute solution from the pure-solvent boiling point T0, molality m, the solvent ebullioscopic constant Kb, and the van 't Hoff factor i using the closed form Tb equals T0 plus i times Kb times m. Colligative boiling-point elevation is the rise of the solution boiling temperature relative to the pure solvent when a non-volatile solute lowers solvent vapor pressure; adding that rise to T0 yields the temperature you measure at boiling for the mixture. The same identity appears in general chemistry labs, colligative problem sets, and process checks where you already know solvent T0 and molality and need a reproducible solution boiling point without table lookups. Typical textbook checks include water at one hundred degrees Celsius with Kb about 0.512 K·kg/mol, m equals 0.5 mol/kg, and i equals 1 yielding Tb equals 100.256, and the same T0, m, and Kb with i equals 2 for a strong 1:1 electrolyte yielding 100.512. The engine uses only finite arithmetic with no network calls, no sampling, and no date-dependent shortcuts.
What the solution boiling point tells you
The boiling point of a dilute ideal solution of a non-volatile solute sits above the pure-solvent boiling point by a colligative amount proportional to the number of solute particles per kilogram of solvent.
The standard linear relation is ΔTb equals i times Kb times m, and the solution boiling point is Tb equals T0 plus ΔTb, where T0 is the pure-solvent boiling temperature on the scale you choose, m is molality in moles of solute per kilogram of solvent, Kb is the solvent-specific ebullioscopic constant with units K·kg/mol (numerically equal to °C·kg/mol for a temperature difference), and i is the van 't Hoff factor that counts the effective particles produced per formula unit.
Ideal non-electrolytes use i equals one; strong electrolytes approach the stoichiometric ion count in the dilute limit, while weak electrolytes use an effective i between one and that count. Zero molality is allowed and yields Tb equal to T0.
Where solution boiling point fits in study, lab, and software
Students meet solution boiling points when a textbook introduces colligative properties after molality, when a lab report asks for the expected boiling temperature of a prepared solution, or when a contest problem gives T0, Kb, and asks for the boiling temperature of a mixture rather than only the rise. Teachers can pre-generate answer keys for modest molalities and integer van 't Hoff factors without trusting opaque calculator apps that silently switch units, drop the particle factor, or forget to add the pure-solvent base temperature.
Developers call the same contract from scripts to seed deterministic test vectors for chemistry education products, to normalize user-entered colligative inputs before plotting phase curves, or to satisfy programming-challenge statements that demand Tb rather than a hand-waved estimate. Process and quality workflows sometimes need a fast offline source of solution boiling temperatures so dilute-solution checks can be validated without reopening a full thermodynamics package.
Product and tutoring tools use the sum when a learner types solvent boiling point, molality, Kb, and i and the UI must show a clean solution temperature with a formula echo.
What you can do with it
Homework and lab Tb checks
Compute expected solution boiling temperature from solvent T0, molality, solvent Kb, and van 't Hoff factor before writing lab reports or checking textbook answers.
Tutoring and chemistry software
Normalize user-entered T0, m, Kb, and i into a stable solution boiling temperature for interactive lessons and solution calculators.
FAQ
What does the solution boiling point calculator cost?
It is free in your browser on this page.
What formula does this tool use?
Tb = T0 + i · Kb · m, where T0 is the pure-solvent boiling point, m is molality (mol/kg), Kb is the ebullioscopic constant (K·kg/mol), and i is the van 't Hoff factor.
What happens if molality is negative?
Molality cannot be negative for this colligative definition of solution boiling point.
Is the result in kelvin or degrees Celsius?
The elevation ΔTb uses kelvin steps that match °C steps for a temperature difference.
How is this different from a boiling-point elevation calculator?
Elevation tools return only ΔTb = i·Kb·m. This calculator also adds the pure-solvent boiling point so you get the absolute solution boiling temperature Tb.
Related tools
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/solution-boiling-point \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"solvent_bp":100,"molality":0.5,"kb":0.512,"i":1}'const res = await fetch("https://api.kit.forhosting.com/chem/solution-boiling-point", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"solvent_bp": 100,
"molality": 0.5,
"kb": 0.512,
"i": 1
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/chem/solution-boiling-point",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"solvent_bp": 100,
"molality": 0.5,
"kb": 0.512,
"i": 1
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/chem/solution-boiling-point", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"solvent_bp":100,"molality":0.5,"kb":0.512,"i":1}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"solvent_bp":100,"molality":0.5,"kb":0.512,"i":1}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/chem/solution-boiling-point", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"solvent_bp": 100,
"molality": 0.5,
"kb": 0.512,
"i": 1
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "chem.solution_boiling_point",
"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. |
Technical notes
What solution boiling point means and what the response contains
This calculator returns the normalized solvent_bp, molality, kb, and i values, the elevation delta_tb, the solution boiling_point rounded to the requested precision, the precision used, the method tag solution_boiling_point, a short formula reminder, and a unit note that Tb shares the scale of solvent_bp. There is no approximate CAS path and no random sampling: the engine either multiplies three finite scalars and adds T0 inside the supported magnitude range or rejects the input with invalid_input. Rejected cases include missing solvent_bp, molality, kb, or i, non-finite values, magnitudes above the documented ceiling, and any negative molality, because a negative moles-per-kilogram figure is non-physical for this definition.
How solvent T0, molality, Kb, and the van 't Hoff factor are read
Optional leading plus signs and scientific notation on numeric strings are allowed when they parse as finite decimals; embedded spaces, hex prefixes, and non-numeric tokens are rejected with a clear message so a bad cell does not become a wrong boiling temperature. The solvent boiling point, constant, and factor are required finite numbers; you supply T0, Kb, and the particle factor that match your problem statement rather than relying on a hidden table or unit conversion. The preferred fields are solvent_bp for the pure-solvent boiling point, molality for m, kb for the ebullioscopic constant, and i for the van 't Hoff factor, but aliases T0, tb0, pure_bp, solvent_boiling_point, and boiling_point_solvent for the solvent temperature, m, b, and molal for molality, Kb, ebullioscopic_constant, boiling_constant, and K_b for the constant, and van_t_hoff, vant_hoff, van_hoff, and factor for i are accepted so spreadsheets, query strings, and typed forms can reuse the same contract. Molality must not be negative: if the value is below zero, the request fails with invalid_input because colligative molality cannot be negative. Zero molality is valid and simply returns boiling_point equal to solvent_bp with zero elevation. An optional precision field, with aliases decimals and dp, chooses how many decimal places to expose for all numeric outputs, defaulting to ten and capped at fifteen so JSON goldens stay stable. Pair the free browser run on this page with the priced API when you need the identical mathematical result inside an automated pipeline without re-implementing Tb equals T0 plus i Kb m yourself.
Where solution boiling point fits in study, lab, and software
On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split — free interactive exploration and a priced, identical API — matches the rest of the KIT tier-A catalog and lets you move from a classroom demo to an automated pipeline without changing the mathematical result. Pair it with boiling-point elevation or molar-concentration tools when you need related solution chemistry steps, and with other chem endpoints when you are building a small lab of free, deterministic colligative helpers.
Integration use cases
Deterministic test fixtures
Generate reproducible boiling_point and delta_tb values for unit tests, property checks, and CI assertions on colligative formulas.