Master Chemistry Through Interactive Learning
What do you want to learn? Search 177+ concept guides, 42+ step-by-step calculators, interactive simulations and practice problems — free forever.
Popular: Accuracy vs Precision: What's the Difference in Chemistry? · Three models of acids and bases · Activation energy: the barrier every reaction must cross · Addition Reactions: Breaking the Double Bond
Explore by subject
Nineteen chemistry subjects, each a complete learning hub with guides, formulas, calculators and practice.
flask Acids & Bases
pH, strong and weak acids, buffers, and titrations.
8 key topicsflask Analytical Chemistry
Measurement science — titrations, spectroscopy, and chromatography.
8 key topicsflask Applied & Everyday Chemistry
Chemistry in food, cleaning, medicine, energy, and the environment.
9 key topicsflask Atomic Structure
Protons, neutrons, electrons — what atoms are made of and how they are organized.
9 key topicsflask Biochemistry
The chemistry of life — proteins, enzymes, carbs, lipids, and nucleic acids.
12 key topicsflask Chemical Bonding & Structure
How atoms stick together — ionic, covalent, and metallic bonds plus molecular shapes.
10 key topicsflask Redox & Electrochemistry
Electron transfer — batteries, electrolysis, and cell potentials.
8 key topicsflask Chemical Equilibrium
Reversible reactions, equilibrium constants, and Le Châtelier's principle.
11 key topicsflask States of Matter & Gases
Solids, liquids, gases — and the gas laws that let you calculate pressure, volume, and temperature.
10 key topicsflask General Chemistry
Matter, measurement, the mole, and chemical reactions — the foundation of everything.
7 key topicsflask Inorganic Chemistry
Coordination compounds, transition metals, and main-group chemistry.
11 key topicsflask Chemical Kinetics
How fast reactions go — rate laws, activation energy, and catalysts.
8 key topicsflask Materials & Environmental Chemistry
Polymers, semiconductors, batteries, pollution, and green chemistry.
7 key topicsflask Math for Chemistry
The quantitative toolkit — logarithms, unit conversions, and significant figures.
9 key topicsflask Nuclear Chemistry
Radioactivity, half-life, fission, and fusion.
11 key topicsflask Organic Chemistry
Carbon compounds — functional groups, nomenclature, isomerism, and reactions.
9 key topicsflask Periodic Table & Periodicity
The map of the elements — groups, periods, and the trends that predict behavior.
10 key topicsflask Solutions & Solubility
Concentration, dilution, solubility, and colligative properties.
10 key topicsflask Thermochemistry & Thermodynamics
Heat, enthalpy, entropy, and Gibbs free energy — the energetics of chemical change.
Reference library
Every element, compound and ion — plus exam-ready study guides and converters.
⚛ Elements
Every chemical element: properties, electron configuration, occurrence, uses and compounds.
32 compounds🧪 Compounds
Important chemical compounds: formulas, molar masses, structures, properties and uses.
32 ions± Ions
Common cations and anions: formulas, charges, formation, naming and example compounds.
8 guides📚 Study Guides
Complete study guides per subject: key formulas, topic checklists, common mistakes and exam tips.
Tool🔁 Unit Converter
Convert between SI and everyday units: length, mass, time, energy, pressure and more.
Tool🧮 Equation Solver
Pick a chemistry equation, choose the unknown and enter the knowns — the solver rearranges it and shows every step.
Featured concept guides
Deep, intuitive explanations — macroscopic, particulate and symbolic thinking.
Accuracy vs Precision: What's the Difference in Chemistry?
Learn the difference between accuracy and precision in chemistry measurements, with the classic target model, systematic vs random error, and percent error calculations.
High SchoolThree models of acids and bases
Compare the three acid-base models — Arrhenius, Brønsted–Lowry, and Lewis — and learn which to use for aqueous solutions, proton transfers, and electron-pair reactions.
High SchoolActivation energy: the barrier every reaction must cross
Learn what activation energy is, how it appears on energy diagrams, and why it — not the overall energy change — controls how fast reactions run.
Introductory CollegeAddition Reactions: Breaking the Double Bond
See how alkenes react by addition across the C=C bond: bromination of ethene, catalytic hydrogenation with nickel, and Markovnikov's rule for HX addition.
High SchoolAir quality chemistry: pollutants, smog, and the Air Quality Index
The chemistry of the air we breathe: common pollutants, how smog forms, and what the Air Quality Index tells you.
High SchoolAlcohols: The Hydroxyl Functional Group
Explore alcohols, compounds carrying the –OH group: primary, secondary and tertiary types, hydrogen bonding, oxidation reactions, and ethanol from fermentation.
Popular calculators
Every calculator shows the formula, the substitution steps and the final answer — never just a number.
🧮 Arrhenius Equation Calculator — k = Ae^(−Ea/RT)
Find a rate constant from the pre-exponential factor, activation energy, and temperature.…
🧮 Average Atomic Mass Calculator
Compute the weighted average atomic mass from isotopic masses and fractional abundances.…
🧮 Buffer pH Calculator — Henderson–Hasselbalch
Estimate buffer pH from pKa and the base-to-acid concentration ratio.…
🧮 Calorimetry Calculator — q = CΔT
Find heat exchanged using a calorimeter's heat capacity and measured temperature change.…
🧮 Cell Potential Calculator — E°cell = E°cathode − E°anode
Find the standard cell potential from the two half-cell reduction potentials.…
🧮 Combined Gas Law Calculator — P₁V₁/T₁ = P₂V₂/T₂
Find the new pressure, volume, or temperature of a fixed amount of gas.…
🧮 Dilution Calculator — M₁V₁ = M₂V₂
Find the final concentration or required volumes when diluting a stock solution.…
🧮 Electrolysis Calculator — Faraday's Laws
Find the mass deposited or liberated from current, time, and electrons per ion.…
Interactive simulations
Change the variables, watch what happens, build real intuition.
Bohr atom light lab
Excite electrons to higher shells and watch them fall back, releasing the exact photons that make each element's spectrum.
InteractiveCalorimetry heat mixer
Mix a hot metal block with cool water in a virtual calorimeter and watch heat flow until both reach one final temperature.
InteractiveGas diffusion mixer
Release two gases on either side of a barrier and watch diffusion mix them, faster when hot and faster when light.
InteractiveEquilibrium shift explorer
Disturb the brown N2O4/NO2 equilibrium with heat, pressure, and concentration changes, and watch it shift to fight back.
InteractiveGas laws piston lab
Squeeze, heat, and cool a gas in a virtual piston and watch pressure, volume, and temperature follow the gas laws.
InteractiveRadioactive half-life lab
Watch a pile of radioactive atoms decay step by step and discover why half of them are always gone after one half-life.
Learning paths
Guided journeys from zero to mastery — no more random browsing.
Analytical Chemistry Foundations Path
Core analytical chemistry skills: measurement quality, concentration, titrations, spectrophotometry, and chromatography.
15 hours · BeginnerChemistry Beginner Path: From Matter to Molecules
A friendly first tour of chemistry for true beginners: matter, measurement, atoms, equations, the mole, and everyday solutions.
25 hours · High SchoolChemistry Exam Prep Drill Path
High-school chemistry exam preparation built around timed drills: stoichiometry, gas laws, equilibrium, acids, thermo, redox, and mixed review.
60 hours · High School to Introductory CollegeGeneral Chemistry Complete Path
A full high-school-to-college introductory chemistry sequence: atoms, bonding, gases, energy, kinetics, equilibrium, acids, and electrochemistry.
25 hours · Introductory CollegeNursing Chemistry Path
Chemistry tailored for nursing and allied health: measurements, solutions, buffers, essential organics, biochemistry, and nuclear medicine basics.
30 hours · Introductory CollegeOrganic Chemistry Foundations Path
Introductory organic chemistry from carbon's bonding behavior through naming, isomerism, reaction families, and polymers.
Chemistry games
Learn by playing — every game ends with a debrief on the chemistry you just used.
Periodic table quiz race
A fast-paced quiz race across the periodic table: name the element, find its position, and sort metals from nonmetals.
GameEquation balancing sprint
Race the clock to balance chemical equations by choosing the right coefficients, from simple combustion to tricky redox reactions.
GameFunctional group detective
Look at molecule structures and identify the functional group hiding inside, from alcohols to amides, against the clock.
GameIon charge match
Flip cards to match ions with their charges and pair cations with anions to build neutral compounds.
GameStoichiometry supply mission
Run a space supply depot: calculate reactants, spot the limiting reactant, and deliver exact product amounts to keep missions on schedule.
Home experiments
Real chemistry with household materials — full procedures and explanations.
Baking soda and vinegar neutralization
Mix baking soda and vinegar to trigger a fizzy neutralization reaction and test how the mixture's acidity changes.
ExperimentBalloon gas laws
Heat and chill a balloon to watch Charles's law inflate and shrink it, then squeeze it to feel Boyle's law.
ExperimentCartesian diver bottle
Build a Cartesian diver from a ketchup packet in a water bottle and make it sink and float with a squeeze.
ExperimentCandy dye chromatography
Separate the hidden dyes inside candy shells and markers with paper chromatography using only water.
ExperimentDensity tower of liquids
Pour honey, soap, water, oil, and alcohol into one glass and watch them stack into a floating rainbow of density layers.
ExperimentSplitting water with a 9V battery
Split water into hydrogen and oxygen with a 9V battery, pencils, and baking soda in this strictly supervised classic.
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