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API · /osmosis-api

Colligative Properties API

healthy 4,006 Subscribers

Colligative-properties maths for solutions as an API, computed locally and deterministically. The osmotic endpoint computes the osmotic pressure by the van 't Hoff equation, π = i·M·R·T, from the molarity, the temperature and the van 't Hoff factor (the number of dissolved particles per formula unit — 1 for sugar, 2 for NaCl, 3 for CaCl₂), reported in atmospheres, bar and kilopascals, and also solves the molarity back from a measured pressure. The freezing endpoint computes the freezing-point depression, ΔTf = i·Kf·m, from the molality and the cryoscopic constant (1.86 °C·kg/mol for water), and the new freezing point. The boiling endpoint computes the boiling-point elevation, ΔTb = i·Kb·m, from the ebullioscopic constant (0.512 °C·kg/mol for water), and the new boiling point. Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry, biology and food-science tools, reverse-osmosis and desalination estimates, antifreeze and de-icing formulation, lab and education apps. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is colligative-properties chemistry; for solution dilution use a dilution API and for pH and buffers use a pH API.

#colligative #osmotic-pressure #chemistry #solutions #freezing-point #developer-tools
api.oanor.com/osmosis-api
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Machine-readable spec so AI agents can integrate this API.

/api/osmosis-api/openapi.json
/api/osmosis-api/llms.txt

Discovery: GET /api/index.json lists every API.

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
86 ms
Server probes · 24h
Subscribers
4,006
active
Total calls
32
last 7 days
status Full status page → · 20 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 2,000 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • Osmotic pressure via van 't Hoff (i·M·R·T)
  • Single-call freezing-point depression
  • JSON output with SI units
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Starter

€5.00 /month

  • 25,000 calls / month
  • 5 requests / second
  • Hard cap (429 above quota, no overage)
  • All four colligative endpoints (osmotic, ΔTf, ΔTb, ΔP)
  • Configurable van 't Hoff factor i
  • Email support
  • Deterministic, instant compute
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Pro

€15.00 /month

  • 150,000 calls / month
  • 12 requests / second
  • Hard cap (429 above quota, no overage)
  • Batch multi-solution requests
  • Molality / molarity / mole-fraction inputs
  • Custom solvent constants (Kf, Kb)
  • Priority support
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Mega

€45.00 /month

  • 765,000 calls / month
  • 30 requests / second
  • Hard cap (429 above quota, no overage)
  • High-throughput classroom & LMS integration
  • Full electrolyte dissociation modelling
  • Bulk solution-table computation
  • SLA-backed uptime
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Colligative Properties API

Colligative-properties chemistry maths as an API, computed locally and deterministically. The freezing-point endpoint computes the freezing-point depression ΔTf = i·Kf·m and the resulting lowered freezing point of a solution, from the molality, the cryoscopic constant (1.86 °C·kg/mol for water) and the van 't Hoff factor i — which is 1 for a non-electrolyte like sugar, about 2 for sodium chloride and about 3 for calcium chloride. The boiling-point endpoint computes the boiling-point elevation ΔTb = i·Kb·m and the raised boiling point, with the ebullioscopic constant (0.512 °C·kg/mol for water). The osmotic-pressure endpoint computes the van 't Hoff osmotic pressure Π = i·M·R·T from the molarity, the temperature and the van 't Hoff factor, the pressure that drives osmosis across a semipermeable membrane, returned in atmospheres, kilopascals and bar. Molality is in mol per kg of solvent, molarity in mol per litre of solution and temperature in kelvin. Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry-education, food-science, antifreeze, desalination and biology app developers, solution and de-icing tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is colligative properties of solutions; for a compound's molar mass use a molar-mass API and for dilution concentrations a dilution API.

api.oanor.com/colligative-api

Electrolysis API

Faraday-law electrolysis maths as an API, computed locally and deterministically. The mass endpoint applies Faraday's first law of electrolysis, m = (Q·M)/(n·F) = (I·t·M)/(n·F), to give the mass of a substance deposited at a cathode or dissolved at an anode from the charge passed — or the current and time — the molar mass and the valence (electrons transferred per ion), with the Faraday constant 96485 C/mol. The charge endpoint inverts it to give the charge Q = (m·n·F)/M and, with a current, the plating time needed to deposit a target mass — the core sizing calculation for electroplating and anodising. The gas-volume endpoint computes the volume of gas evolved during electrolysis, moles = Q/(n·F) and volume = moles × 22.414 L/mol at STP, using the electrons per gas molecule (two for hydrogen, four for oxygen in water electrolysis). Molar mass is in g/mol, current in amperes, time in seconds, charge in coulombs and mass in grams. Everything is computed locally and deterministically, so it is instant and private. Ideal for electroplating, anodising, battery, hydrogen-production and chemistry-education app developers, plating-time and gas-yield tools, and electrochemistry teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is electrolysis (Faraday's laws); for cell potential and the Nernst equation use an electrochemistry Nernst API.

api.oanor.com/electrolysis-api

Reaction Stoichiometry API

Chemical reaction-stoichiometry maths as an API, computed locally and deterministically. The limiting-reagent endpoint takes two reactants with their amounts in moles and their balanced-equation coefficients and finds which one runs out first — the limiting reagent — by comparing the moles/coefficient ratio (the reaction extent), and returns how much of the excess reagent is left over. The yield endpoint computes the theoretical yield of a product, in moles and grams, from the limiting reagent and the product's stoichiometric coefficient and molar mass, n_product = n_limiting·(coeff_product/coeff_limiting), and — given the actual yield — the percent yield. The mole-mass endpoint converts between moles, mass and the number of particles for a given molar mass, using moles = mass / molar_mass and N = moles · Avogadro's number (6.02214076e23). Amounts are in moles, masses in grams and molar masses in g/mol. Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry-education, lab, pharmaceutical and chemical-engineering app developers, reaction-planning and yield tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is reaction stoichiometry; for a compound's molar mass from its formula use a molar-mass API and for solution concentrations a dilution API.

api.oanor.com/stoichiometry-api

Electrochemistry Nernst API

Electrochemistry maths as an API, computed locally and deterministically. The nernst endpoint applies the Nernst equation, E = E° − (R·T/nF)·ln Q, to give the actual electrode or cell potential under non-standard conditions from the standard potential E°, the number of electrons transferred n, the reaction quotient Q and the temperature — at 25 °C this reduces to E = E° − (0.05916/n)·log10 Q, and a larger Q (more product) lowers the potential. The cell-potential endpoint computes a galvanic cell's standard EMF from the cathode and anode standard reduction potentials, E°cell = E°cathode − E°anode, together with the standard Gibbs free energy ΔG° = −nF·E°cell and whether the reaction is spontaneous. The equilibrium endpoint computes the equilibrium constant of a redox reaction, K = exp(nF·E°cell / RT), and the corresponding ΔG°, from the standard cell potential and the electrons transferred. Potentials are in volts, energies in kJ/mol, the Faraday constant is 96485 C/mol and the gas constant 8.314 J/mol·K. Everything is computed locally and deterministically, so it is instant and private. Ideal for chemistry-education, battery, corrosion, electroplating and electroanalytical app developers, galvanic-cell and redox tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is electrochemistry; for acid-base pH use a pH API and for reaction-rate kinetics an Arrhenius API.

api.oanor.com/nernst-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Colligative Properties API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Colligative Properties API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Colligative Properties API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Colligative Properties API cost?
Colligative Properties API has a free tier with 100 calls / month. Paid plans start at €5.00 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Colligative Properties API GDPR-compliant?
All requests to Colligative Properties API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

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Code snippets

Sign up to get an API key, then call any path under your slug.

curl https://api.oanor.com/osmosis-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/osmosis-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/osmosis-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);
import requests
r = requests.get(
    "https://api.oanor.com/osmosis-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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