High School Chemistry · Practice Hub
High School Chemistry Practice Problems by Unit
Pick the unit you need, work the problems, and use the worked solutions to catch exactly where your thinking went off track — 2,642 practice problems across all 15 units, built to teach you how to solve, not just hand you an answer.
01
Pick a unit you are in right now and work on the topic that will help you most. Not sure? Start with the unit guide.
02
Try the samples first and notice what the problem is really asking you to do — not just whether you got it right.
03
Choose your problem type — calculation, concept, or multi-step — when you want to drill one kind of thinking specifically.
04
Generate a set — Quick (3), Standard (9), or Extended (18) — and use the worked solution to sharpen your thinking while the idea is still fresh.
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Start with the unit you need right now
Each unit page starts with free samples, then opens into longer premium sets when you want more practice on the same skill.
Unit 1
215 problems
Quick 3 • Standard 9 • Extended 18
Intro to Chemistry & Lab Safety
Significant figures, unit conversions, and lab safety — the vocabulary-heavy start of chemistry.
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Unit 2
179 problems
Quick 3 • Standard 9 • Extended 18
Matter
Physical vs. chemical changes, pure substances vs. mixtures. The vocabulary trips more students up than the concepts do.
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Unit 3
174 problems
Quick 3 • Standard 9 • Extended 18
Atomic Structure
Protons, neutrons, electrons, and isotopes. This unit is mostly about reading the notation correctly — and getting every number in the right place.
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Unit 4
171 problems
Quick 3 • Standard 9 • Extended 18
Electron Configuration
Orbital filling rules and full electron configurations. Students usually lose points on the exceptions, not the basics.
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Unit 5
174 problems
Quick 3 • Standard 9 • Extended 18
Periodic Table & Trends
Electronegativity, atomic radius, ionization energy. Expect comparison questions, not just definitions.
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Unit 6
174 problems
Quick 3 • Standard 9 • Extended 18
Nomenclature
Naming ionic and covalent compounds. The rules are learnable — the problem is applying the right set to the right compound.
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Unit 7
174 problems
Quick 3 • Standard 9 • Extended 18
Moles
Mole conversions — mass, particles, moles, molar mass. If you are still unclear on the factor-label method, this is the unit to nail down first.
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Unit 8
174 problems
Quick 3 • Standard 9 • Extended 18
Chemical Reactions
Reaction types and balancing equations. Most students can balance — fewer can correctly identify which type of reaction they are looking at.
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Unit 9
174 problems
Quick 3 • Standard 9 • Extended 18
Stoichiometry
Mole ratios, limiting reagents, and percent yield. This is where stoichiometry gets harder — and where most students hit a wall.
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Unit 10
171 problems
Quick 3 • Standard 9 • Extended 18
Chemical Bonding
Lewis structures, bond types, and polarity. Drawing the structure correctly is half of every problem in this unit.
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Unit 11
174 problems
Quick 3 • Standard 9 • Extended 18
Energy and Thermochemistry
Heat flow and calorimetry calculations. The equations are straightforward — the sign conventions are where students make mistakes.
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Unit 12
174 problems
Quick 3 • Standard 9 • Extended 18
Gas Laws
Gas law relationships and the ideal gas equation. If the variables are not straight in your head, these problems fall apart fast.
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Unit 13
172 problems
Quick 3 • Standard 9 • Extended 18
Solutions
Molarity, dilution, and solution calculations. There are more unit conversions here than students usually expect.
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Unit 14
171 problems
Quick 3 • Standard 9 • Extended 18
Chemical Equilibrium
Keq expressions, ICE tables, and Le Chatelier's Principle. Give this unit the time it needs — the ideas connect in ways that take a moment to land.
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Unit 15
171 problems
Quick 3 • Standard 9 • Extended 18
Acids & Bases
pH calculations, strong vs. weak acids, and neutralization. The log math is only part of what students find difficult.
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Need the explanation before more practice?
If you are still guessing at the setup, stop and fix that first. Each unit has a full study guide with concept explanations, worked examples, and interactive tools. If you want the bigger picture of how this site is built to help you, read How ChemUnlocked Works.
High School Chemistry · Practice Hub