ChemUnlocked

ChemUnlocked helps you understand chemistry, not just survive the next assignment.

If chemistry has started to feel confusing, start here. This is where you slow it down, fix the gaps, and build it back clearly. ChemUnlocked gives you teacher-led study guides, worked examples, and 1,277 practice problems — enough to review every unit before the test without guessing your way through it.

Start with your chemistry unit → Try chemistry practice problems →
15 units · 1,277 practice problems Free to use Works unit by unit — start anywhere

How ChemUnlocked helps you learn general chemistry

Understand

Study guides that explain the ideas, not just the formulas

Each guide starts by explaining what is actually going on — the idea, the logic, the why — before any formula shows up. You are not just memorizing steps. You are learning what the problem is asking, why the method works, and what to notice before you start solving.
Practice

Practice problems that show what you actually know

The practice sets change each time, so you cannot rely on memory alone. Use them to check your understanding, find weak spots early, and see the full reasoning in the worked solutions. This is what students usually miss: getting one version right is not the same as being ready for the next version.
Study smart

Study skills that help chemistry stick

Most students reread when they feel stuck. That is not studying — it is re-exposing yourself to the same material without ever testing whether it actually stuck. These guides show you how to replace passive review with strategies that build real recall, so you feel ready on test day instead of just familiar with the material.
Practice Problems

Use practice to check your understanding before the test does

Choose a unit, start with a Quick Set of 3, and then compare your thinking to the worked solution. When you want a longer review block, move into Standard Sets of 9 or Extended Sets of 18. Remember, the point is not just to see whether you were right. The point is to catch where your thinking went off track before that weak spot shows up on the test.

Open the chemistry practice hub → Browse practice by unit →
1,277
practice problems
15
unit banks
3
quick
9
standard
18
extended
15 Units

Review the chemistry unit you need right now

Start with the topic your class is on, or go back and rebuild a unit that never fully clicked the first time. Not sure where to start? Go back one unit further than you think you need to. If this feels shaky, do not skip straight to random practice. Fix the foundation first, then come back and test it.

01 Intro to Chemistry & Lab Safety 02 Matter 03 Atomic Structure 04 Electron Configuration 05 Periodic Table & Trends 06 Nomenclature 07 Moles 08 Chemical Reactions 09 Stoichiometry 10 Chemical Bonding 11 Energy & Thermochemistry 12 Gas Laws 13 Solutions 14 Chemical Equilibrium 15 Acids & Bases
See all chemistry practice by unit → Learn how to study chemistry more effectively → See how ChemUnlocked is built to help you study →
Study Skills

A lot of students spend time on chemistry without fixing the part that is actually breaking down

See all study skills guides →

These guides show you how to study chemistry in a way that leads to stronger recall, better problem solving, and fewer false signals that make you think you know it when you do not.

Guide 01 · 6 min read

How to Study Smarter, Not Longer

Notice this pattern early: strategies that feel a little harder usually teach you more than rereading ever will.
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Guide 02 · 7 min read

Why Practice Tests Beat Rereading

This is what students usually miss: testing yourself is not just for checking. It is one of the fastest ways to build usable memory.
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Guide 03 · 6 min read

The Flashcard Method That Works

If flashcards have not been helping, the problem is usually the way they are written or used, not the idea of flashcards itself.
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See all study skills guides →
Introductory General Chemistry · Study Hub