# EqCalc-G — Gas Chemical Equilibrium

> Gas Chemical Equilibrium (iPhone/iPad app by Jon Tonouchi.)

- Source: https://appshunter.io/ios/app/eqcalc-g/id6759407516 (this page in markdown: same URL + `.md`)
- Developer: [Jon Tonouchi](https://appshunter.io/developer/1814163396)
- Category: Education, Productivity
- Price: Free with in-app purchases
- Age rating: 17+
- Requires: iOS 18.2 · 11 MB
- Languages: American English
- Released: 2026-03-17
- Data updated: 2026-06-06
- User reviews in markdown: https://appshunter.io/ios/app/eqcalc-g/id6759407516/reviews.md

## What is EqCalc?

EqCalc‑G is an educational and engineering reference tool for calculating gaseous chemical equilibrium using Gibbs free‑energy minimization. Designed for students, researchers, and practicing engineers, the app provides a fast, portable way to explore equilibrium behavior in hydrogen and hydrocarbon systems under ideal‑gas assumptions.

Key Features:
	•	Includes a publicly available thermochemical dataset derived from NASA curve‑fits of the NIST‑JANAF tables for selected species
	•	Import your own thermochemical datasets in Aerotherm, Chemkin, or NASA CEA formats
	•	Flexible reactant specification:

                - Define mixtures on a mole or mass basis
                - Or specify fuel mixture, air, and fuel‑air equivalence ratio
	•	Export results easily by copying output to the clipboard for use in your favorite notes or spreadsheet apps

Basic vs. Plus Version:
The free Basic version supports fixed enthalpy and pressure equilibrium calculations.
Upgrade to Plus version to unlock additional problem types:
	•	Fixed temperature & pressure
	•	Fixed entropy & pressure
	•	Fixed internal energy & volume
	•	Fixed temperature & volume
	•	Fixed entropy & volume

NASA/NIST Notice:
Use of NASA and NIST thermochemical data does not imply endorsement, certification, recommendation, or approval of this app, its developer, or any results produced. NASA and NIST provide no warranties and assume no liability for the use of their data within this app.

Privacy Policy: https://jtonouchi.github.io/EqCalc-G/privacy
Terms and Conditions: https://jtonouchi.github.io/EqCalc-G/terms

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Plus Version | $2.99 | one-time |



## Version history (last 2 releases)

### 1.1 — 2026-05-05

- Specify different temperatures for reactants, fuel and air
- Bug fixes

### 1.0 — 2026-03-17

No release notes.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-06.*