# DrPhos' Ionic Compounds vs A2L Certification Test Prep

The clearest difference is price: A2L Certification Test Prep at Free against DrPhos' Ionic Compounds's $0.99. A2L Certification Test Prep also leads on update cadence (every 5 days vs every 3 weeks) and iOS requirement (15.1 vs 17.0). DrPhos' Ionic Compounds's advantage is ads (none vs shown). On rating, ratings volume, in-app purchases and device support there is nothing between them.

A2L Certification Test Prep is free to download; DrPhos' Ionic Compounds costs $0.99 up front. DrPhos' Ionic Compounds sells 11 one-off in-app purchases and A2L Certification Test Prep sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

On the App Store both sit at effectively the same score — 4.9 for DrPhos' Ionic Compounds against 5.0 for A2L Certification Test Prep. Both are backed by a comparable volume of ratings — 8 and 3 respectively.

DrPhos' Ionic Compounds ships an update every 3 weeks, A2L Certification Test Prep every 5 days. The most recent releases landed on September 30, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | DrPhos' Ionic Compounds | A2L Certification Test Prep |
| --- | --- | --- |
| Price | $0.99 | **Free** |
| Rating | [4.9 (8 ratings)](https://appshunter.io/ios/app/drphos-ionic-compounds/id6473097401/reviews) | **[5.0 (3 ratings)](https://appshunter.io/ios/app/a2l-certification-test-prep/id6760899340/reviews)** |
| Number of ratings | **8** | 3 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 3 weeks | **Every 5 days** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 15 MB | 47 MB |
| Requires iOS | 17.0 | **15.1** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Monte L Helm](https://appshunter.io/developer/1715082616) | [Mike Watson](https://appshunter.io/developer/1848411021) |

## What reviewers say

### DrPhos' Ionic Compounds

[App page](https://appshunter.io/ios/app/drphos-ionic-compounds/id6473097401)

This app helps students learn and practice forming correct chemical formulas for ionic compounds. It supports a wide range of ions, including polyatomic ones, and dynamically generates formulas with proper subscripts and parentheses. It's designed to reinforce naming rules and charge balancing through an interactive interface.

**Highlights:** Extensive cation and anion list, Support for polyatomic ions, Real-time formula generation, Subscript and parenthesis formatting, Reinforces naming rules, Charge balancing practice

**Features:** macOS Compatibility

**In-app purchases (11)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Ionic Compound Builder | Free | one-time |
| Science Calculator | $0.99 | one-time |
| Significant Figures Counter | $0.99 | one-time |
| Quadratic Equation Solver | $0.99 | one-time |
| Kinetics | $0.99 | one-time |
| Molar Mass Calculator | $0.99 | one-time |
| Naming Compounds | $0.99 | one-time |
| Reaction Balancer | $0.99 | one-time |
| Stoichiometry | $0.99 | one-time |
| Solution Concentrations | $0.99 | one-time |
| pH Calculator | $0.99 | one-time |


### A2L Certification Test Prep

[App page](https://appshunter.io/ios/app/a2l-certification-test-prep/id6760899340)

This professional tool provides accurate refrigerant charging calculations for next-generation gases like R-454B and R-32. It features error-proof charging, a maximum allowable charge calculator, and offline reference materials for HVAC technicians.

**Highlights:** A2L-ready for R-454B and R-32, Error-proof superheat/subcooling calculations, Integrated Max Allowable Charge Calculator, Branded PDF field reports, Offline P/T charts and safety guides, No account or login required

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| A2L SafeCharge Pro | $1.99 | one-time |


## Frequently asked questions

### Is DrPhos' Ionic Compounds free?

DrPhos' Ionic Compounds costs $0.99, and also offers in-app purchases.

### Is A2L Certification Test Prep free?

A2L Certification Test Prep is free to download, with in-app purchases available.

### Which has better reviews, DrPhos' Ionic Compounds or A2L Certification Test Prep?

A2L Certification Test Prep is rated higher. DrPhos' Ionic Compounds averages 4.9 out of 5 from 8 ratings, while A2L Certification Test Prep averages 5.0 from 3 ratings.

### Do DrPhos' Ionic Compounds or A2L Certification Test Prep have ads?

A2L Certification Test Prep shows ads; DrPhos' Ionic Compounds does not.

### Which is updated more often, DrPhos' Ionic Compounds or A2L Certification Test Prep?

DrPhos' Ionic Compounds ships an update every 3 weeks, and A2L Certification Test Prep every 5 days. Most recently, DrPhos' Ionic Compounds was updated on September 30, 2026 and A2L Certification Test Prep on October 7, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*