Balancing Chemical Equations Game & Calculator
Balance real reactions, press React! and watch every atom move. 36 stages from counting atoms to AP Chemistry, a Daily Balance, and a balancer with steps.
Eight chapters, from counting atoms to AP redox. Earn up to three stars on every stage.
Solve all five, then share your 🟩🟨🟥 grid with your class. Keep the streak going.
Change the big numbers (coefficients) with + and −. Subscripts are locked.
Watch the pans: the beam weighs both sides in atomic mass units, and the atom ledger compares every element.
Press React! Every atom must find a place in the products. None left over, none missing.
Campaign map
Badges
Pick a reaction, then use the −/+ steppers to set each coefficient. The beam levels and turns lime when both sides carry the same atoms.
Balancing Equations Quiz
Balance 5 randomised chemical equations by typing the correct coefficients. Covers synthesis, decomposition, combustion, and replacement reactions. Score 5/5 for ★★★.
1 Overview
This tool teaches and checks the balancing of chemical equations. It has five modes: 🎮 Play (the balancing equations game: a campaign, a Daily Balance and a Speed Lab), 🧮 Balancer (balances any equation you type, with step-by-step working), Sandbox (free coefficient tuning on a balance beam for any of the 60+ reactions), Learn (concept cards on conservation of mass, the balancing method and reaction types) and Quiz (5 randomised equations with a star rating). The reactions cover synthesis, decomposition, combustion, single and double replacement, and redox.
2 Play Mode — the Game
- Campaign: eight chapters. Chapter 1, Atom Census, is about counting: how many atoms of an element are in a formula with a coefficient, brackets or a hydrate. Chapters 2–8 are balancing: synthesis, decomposition, single replacement, double replacement, combustion, redox, and a final AP-level chapter. Clear a chapter to unlock the next. Teachers can unlock every chapter with the tick box under the map.
- Playing a stage: change the big numbers in front of each formula with + and −, by typing, or with the arrow keys. The subscripts are locked: pressing one explains why. The molecules in the two pans change as you go. The beam weighs both sides in atomic mass units (u), and the atom ledger under the canvas compares every element, left against right.
- Press ⚗️ React! (or Enter). Every reactant atom flies to a place in a product molecule. If the equation is not balanced, atoms are left over or places stay empty, and the canvas names them. Coefficients that balance but share a factor (4, 2, 4 for water) are not accepted: write the smallest whole numbers.
- Stars: three for reacting right first time with no hint and close to par (the fewest presses from all ones); two for at most one wrong try and one hint; one for any solve. 💡 Hint works in three steps: which element is off, which formula to change next (in the same order as the step-by-step method), then the coefficient itself.
- Daily Balance: five equations, the same for everyone on a given day, from easy to AP. Finish to get a shareable 🟩🟨🟥 grid and keep your day streak. Speed Lab: 90 seconds at Intro, Honors or AP level. An equation clears the moment it balances; skipping costs 5 seconds.
- Challenge a friend: type any equation into the Balancer tab, then press Play it as a challenge or Copy challenge link. Whoever opens the link plays that equation.
- XP, ranks (Lab Rookie up to Lavoisier Laureate) and badges are saved in this browser only. Nothing is sent anywhere and there is no account. Reset progress clears them.
- How the molecules are drawn: small molecules have their real shapes (water is bent at 104.5°, CO₂ is straight), and saturated chains such as propane are drawn as zig-zags. Ionic compounds and large molecules are drawn as a cluster of their atoms: one formula unit, as a count of atoms, not a structure.
3 Sandbox Mode
- Pick a reaction from the chips, or keep the default. Every coefficient starts at 1, so the equation begins unbalanced.
- Use the − / + steppers under each formula to change its coefficient. The balance beam on the right tilts toward the heavier side and the element table shows the atom count of each element on both sides — green ✓ when an element matches, red ≠ when it does not.
- When every element matches, the beam levels, turns lime, and shows ✓ BALANCED.
- ⚖ Auto-Balance animates the coefficients up to the correct answer. ↻ Reset returns all coefficients to 1.
- Balance your own equation: type any equation in the Balancer tab using
->or=between the two sides (e.g.C3H8 + O2 -> CO2 + H2O) and click Balance for the instant answer. Check it on the balance beam opens it here. - Right-click the canvas for a menu: Auto-Balance, Save as Image, Copy Balanced Equation, or Reset. The speaker icon mutes sounds.
4 Learn Mode
Read concept cards across four tabs: Basics (conservation of mass, coefficient vs subscript, counting atoms), How to Balance (the four-step method — count, metals first, odd/even trick, reduce to lowest terms), Reaction Types (synthesis, decomposition, combustion, replacement with examples), and Tips & Mistakes (never change subscripts, treat polyatomic ions as units, using fractions).
5 Quiz Mode
Quiz: 5 randomised equations. Type the coefficients and Submit — each answer is marked and the correct balanced equation is shown. The result screen gives a star rating (5/5 = ★★★) and lists every equation with the correct answer to review.
6 Key Concepts & Tips
- Only change coefficients (the big numbers in front) — never the subscripts inside a formula.
- Balance metals first, then non-metals, and H and O last.
- If oxygen comes out odd, use a fraction like
7/2 O₂then multiply everything by 2. - Reduce every answer to the smallest whole-number ratio — the game and the Quiz expect lowest terms.
- Keep polyatomic ions (SO₄, NO₃, OH) together as a single group when they survive the reaction.
Balancing Chemical Equations Game — How to Play
This free balancing chemical equations game runs in your browser with no sign-up. The reactant molecules sit in the left pan of a beam balance and the product molecules in the right. The beam weighs both sides with real atomic masses, and an atom ledger under it compares every element, left against right. Change the big numbers in front of each formula (the coefficients), then press React!. Every atom on the left flies across to a place in a product molecule. If the equation is balanced, every place fills and nothing is left over. If it is not, the game shows the leftover atoms (“atoms can’t be destroyed”) and the empty places (“atoms can’t appear from nothing”). That is the law of conservation of mass, which Antoine Lavoisier stated in 1789, made visible one atom at a time.
- Campaign: 8 chapters and 36 stages, each worth up to three stars. Atom Census teaches counting atoms (subscripts, brackets such as Ca(OH)₂, hydrates such as CuSO₄·5H₂O). Then there is one chapter per reaction type: synthesis, decomposition, single replacement, double replacement with polyatomic ions, combustion and redox. The final chapter is an AP-level gauntlet whose largest coefficient is 163.
- Daily Balance: five equations, the same for every player each day, from easy to AP. Finish to get a shareable 🟩🟨🟥 result grid and keep your day streak going.
- Speed Lab: balance as many equations as you can in 90 seconds, at Intro, Honors or AP level.
- Challenge a friend: balance any equation in the Balancer tab and send its challenge link.
Three stars means reacting right first time with no hint. Hints come in three steps (which element is off, which formula to change next, then the coefficient itself), and they follow the same order as the step-by-step method below. So they teach the method rather than just give the answer. Answers must be in lowest terms: 4, 2, 4 for water balances the atoms, but the game asks you to divide by 2. And the subscripts are locked. Try to change one and the game explains that H₂O₂ is hydrogen peroxide, not water.
What Does It Mean to Balance a Chemical Equation?
A chemical equation is balanced when every element has the same number of atoms on the reactant side and the product side. This is the law of conservation of mass: atoms are rearranged in a reaction, never created or destroyed. You balance an equation by placing coefficients, the large numbers in front of each formula, and nothing else. The formation of water is the classic first example:
H₂ + O₂ → H₂O (unbalanced) ⟶ 2H₂ + O₂ → 2H₂O (balanced)
Balancing Chemical Equations Practice Problems with Answers
Twenty classic equations to practice on, from easy to hard. Cover the Balanced column and try each one first. These are the reactions that come up again and again in high school and AP Chemistry: combustion of fuels, rusting, photosynthesis and respiration, the Haber process, neutralization and precipitation. Every answer was computed by this tool's own balancer as the smallest whole-number ratio, and it is checked automatically against an independent textbook table. Click any answer to open its step-by-step working in the Balancer tab.
| Reaction | Unbalanced | Balanced | Type | Level |
|---|---|---|---|---|
| Hydrogen burns in oxygen | H2 + O2 → H2O | 2H2 + O2 → 2H2O | Synthesis | Easy |
| Methane combustion | CH4 + O2 → CO2 + H2O | CH4 + 2O2 → CO2 + 2H2O | Combustion | Easy |
| Propane combustion | C3H8 + O2 → CO2 + H2O | C3H8 + 5O2 → 3CO2 + 4H2O | Combustion | Medium |
| Ethane combustion | C2H6 + O2 → CO2 + H2O | 2C2H6 + 7O2 → 4CO2 + 6H2O | Combustion | Medium |
| Aerobic respiration | C6H12O6 + O2 → CO2 + H2O | C6H12O6 + 6O2 → 6CO2 + 6H2O | Combustion | Medium |
| Photosynthesis | CO2 + H2O → C6H12O6 + O2 | 6CO2 + 6H2O → C6H12O6 + 6O2 | Redox | Medium |
| Haber process (ammonia) | N2 + H2 → NH3 | N2 + 3H2 → 2NH3 | Synthesis | Easy |
| Iron rusting (iron(III) oxide) | Fe + O2 → Fe2O3 | 4Fe + 3O2 → 2Fe2O3 | Synthesis | Medium |
| Aluminum burns in oxygen | Al + O2 → Al2O3 | 4Al + 3O2 → 2Al2O3 | Synthesis | Medium |
| Magnesium burns in oxygen | Mg + O2 → MgO | 2Mg + O2 → 2MgO | Synthesis | Easy |
| Blast furnace reduction | Fe2O3 + CO → Fe + CO2 | Fe2O3 + 3CO → 2Fe + 3CO2 | Redox | Medium |
| Thermal decomposition of limestone | CaCO3 → CaO + CO2 | CaCO3 → CaO + CO2 | Decomposition | Easy |
| Decomposition of potassium chlorate | KClO3 → KCl + O2 | 2KClO3 → 2KCl + 3O2 | Decomposition | Medium |
| Zinc and hydrochloric acid | Zn + HCl → ZnCl2 + H2 | Zn + 2HCl → ZnCl2 + H2 | Single replacement | Easy |
| Neutralization (NaOH + HCl) | HCl + NaOH → NaCl + H2O | HCl + NaOH → NaCl + H2O | Double replacement | Easy |
| Silver chloride precipitate | AgNO3 + NaCl → AgCl + NaNO3 | AgNO3 + NaCl → AgCl + NaNO3 | Double replacement | Easy |
| Sodium and water | Na + H2O → NaOH + H2 | 2Na + 2H2O → 2NaOH + H2 | Single replacement | Medium |
| Ostwald process (ammonia oxidation) | NH3 + O2 → NO + H2O | 4NH3 + 5O2 → 4NO + 6H2O | Redox | Hard |
| Copper and dilute nitric acid | Cu + HNO3 → Cu(NO3)2 + NO + H2O | 3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O | Redox | Hard |
| Permanganate oxidises HCl | KMnO4 + HCl → KCl + MnCl2 + H2O + Cl2 | 2KMnO4 + 16HCl → 2KCl + 2MnCl2 + 8H2O + 5Cl2 | Redox | Hard |
How to Balance a Chemical Equation Step by Step
- Write correct formulas for every reactant and product. Never change them afterwards.
- Count the atoms of each element on both sides. In the game, the atom ledger under the balance does this for you.
- Balance metals first, then other non-metals: elements that appear in only one formula on each side.
- Balance hydrogen, then oxygen, last, because they appear in many formulas. Use a fraction such as 7/2 if oxygen comes out odd.
- Clear fractions and reduce: multiply every coefficient by the same number, then check that the coefficients share no common factor.
The inspection method (metals → non-metals → H → O)
Inspection is trial by reasoning: fix one coefficient, then let each element force the next one. Take ethane, C₂H₆ + O₂ → CO₂ + H₂O. Set C₂H₆ to 1. Carbon: 2 on the left, so CO₂ = 2. Hydrogen: 6 on the left, so H₂O = 3. Oxygen: the right now holds 2×2 + 3 = 7 atoms, so O₂ = 7/2. Multiply everything by 2 to clear the fraction: 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O. Once an element is balanced it stays balanced, because no earlier coefficient is changed again.
The algebraic method (simultaneous equations) — worked on Fe₂O₃ + CO
The algebraic method always works, including on redox equations where inspection gets stuck. Give each formula a letter: a Fe₂O₃ + b CO → c Fe + d CO₂. Write one equation per element:
Fe: 2a = c
C: b = d
O: 3a + b = 2d
Set a = 1. Iron gives c = 2. Carbon gives b = d, so oxygen becomes 3 + b = 2b and b = 3, d = 3. The blast-furnace equation is Fe₂O₃ + 3CO → 2Fe + 3CO₂. This calculator solves the same system exactly, as fractions, and scales the result to the smallest whole numbers. That is why it never rounds and never guesses.
Worked example: combustion of propane
Take C₃H₈ + O₂ → CO₂ + H₂O. Balance carbon first: 3 carbons in propane means 3 CO₂. Balance hydrogen next: 8 hydrogens means 4 H₂O. Then count oxygen on the right: 3×2 + 4×1 = 10, so 5 O₂ on the left. The balanced equation is C₃H₈ + 5O₂ → 3CO₂ + 4H₂O. It is stage 2 of the Burn It chapter in the game.
Is This Equation Balanced? How to Check
To check any chemical equation, multiply each coefficient by each subscript, add up the atoms of every element on each side, and compare. It is balanced only if every element matches and the coefficients share no common factor. Take 2NH₃ + 2O₂ → 2NO + 3H₂O. Nitrogen is 2 and 2, and hydrogen is 6 and 6, but oxygen is 4 on the left against 2 + 3 = 5 on the right. So it is not balanced. The correct equation is 4NH₃ + 5O₂ → 4NO + 6H₂O: N 4 = 4, H 12 = 12, O 10 = 10. In the game, the atom ledger does this count live as you change each coefficient, and a mass check backs it up: a balanced equation weighs the same on both pans.
Coefficient vs Subscript — The Rule You Cannot Break
You may change coefficients, but never subscripts. A coefficient multiplies the whole formula: 2H₂O means two water molecules. A subscript counts atoms inside one formula: the 2 in H₂O means two hydrogen atoms in each molecule. Changing H₂O to H₂O₂ does make the arithmetic work, but it turns water into hydrogen peroxide, a different substance. The game locks the subscripts, so it builds the right habit. So what does the 3 in front of O₂ mean? It means three separate O₂ molecules, six oxygen atoms in all, not one molecule of six oxygen atoms bonded together.
The Five Reaction Types You Will Balance
The built-in library groups its 60+ reactions by type so you can practice each pattern: synthesis (A + B → AB, e.g. N₂ + 3H₂ → 2NH₃), decomposition (AB → A + B, e.g. 2H₂O₂ → 2H₂O + O₂), combustion (fuel + O₂ → CO₂ + H₂O), single replacement (A + BC → AC + B, e.g. Zn + 2HCl → ZnCl₂ + H₂) and double replacement (AB + CD → AD + CB, e.g. AgNO₃ + NaCl → AgCl + NaNO₃). The harder chapters add redox equations such as the reaction of copper with nitric acid. Recognising the type often tells you where to start.
Chemical Equation Balancer with Steps (Calculator)
Stuck on a homework equation? Open the Balancer tab. This free balancing chemical equations calculator balances any equation you type and shows the working. Enter the unbalanced equation, for example C3H8 + O2 -> CO2 + H2O, press Balance, and you get the smallest whole-number coefficients (C₃H₈ + 5O₂ → 3CO₂ + 4H₂O) with a step-by-step solution underneath: the atom count, the inspection method one element at a time, the algebraic method, and a final check. Then press Play it as a challenge to balance it yourself in the game, or Check it on the balance beam to see it in the Sandbox. It is free, online, and needs no sign-up, download or app.
How to type an equation into the balancer
| You type | Read as |
|---|---|
H2 + O2 -> H2O | H₂ + O₂ → H₂O. Use ->, = or → for the arrow. |
Ca(OH)2 | Brackets multiply everything inside: Ca 1, O 2, H 2. Square brackets work too. |
CuSO4.5H2O | A hydrate. A full stop or a middle dot (·) joins the water of crystallisation. |
NaCl, not Nacl | Element symbols are one capital letter, optionally followed by one lowercase letter. |
2H2 + O2 -> H2O | Coefficients you type are ignored; the balancer works them out again. |
Two cases are reported honestly instead of forced into an answer. An equation such as C + O₂ → CO + CO₂ can be balanced in infinitely many ratios, so the tool asks you to split it into two reactions. An equation that only balances backwards is flagged so you can swap the sides. The balancer does not yet accept ionic charges (such as Fe³⁺ or electrons), so half-equations must be balanced by hand.
What the step-by-step solution shows
Open Show step-by-step working under any result. It shows four stages, each computed for your equation: (1) a table of atoms on each side with every coefficient set to 1; (2) the inspection method: start with the most complex formula at 1, then balance metals, other non-metals, hydrogen and oxygen in that order, using a fraction where needed and multiplying through at the end; (3) the algebraic method: a letter for each formula and one equation for each element; (4) a final check table with every element ticked. For a few redox equations no element is left with a single unknown part-way through. The working says so, and then finishes with the algebraic equations instead of guessing.
Balancing Equations for Middle School, High School & AP Chemistry
Middle school science asks you to show that atoms are conserved and to count them. Start with the Atom Census chapter and the easy rows of the practice table. High school chemistry, including honors, expects you to balance synthesis, decomposition, single and double replacement, and combustion equations by inspection. Those are chapters 2 to 6 of the campaign, and the Speed Lab's Intro and Honors levels. AP Chemistry adds redox equations with large coefficients and asks you to use balanced equations for stoichiometry. Play the Electron Shuffle chapter, the AP Gauntlet and the Speed Lab's AP level. The same skill is assessed in GCSE, A-Level and IB Chemistry, so the levels map across.
A Free Alternative to Balancing Equations Worksheets
A worksheet checks your answer once, at the end. This balancing chemical equations practice checks every attempt as you make it, shows you exactly which atoms are wrong, and never runs out of problems. The 60+ reaction library feeds the campaign, the Daily Balance and the Speed Lab. The Quiz tab is a short self-marking practice test: five random equations, scored at the end, with every correct answer shown. Teachers can project the game as a class warm-up, set a chapter as homework (tick Unlock every chapter to open any of them), or use the Daily Balance as a bell-ringer: everyone gets the same five equations and can compare their result grids.
Balancing Chemical Equations Simulation & Interactive Practice
An answer-only calculator gives you the coefficients and stops. An interactive balancing chemical equations simulation shows why they are right. Teachers often assign the PhET balancing simulation and its game for this. This tool covers the same idea at a larger scale: 60+ preset reactions instead of a handful, any equation you type, and a Sandbox tab where you step each coefficient and watch the beam and the element table respond without scoring. It works as a free virtual lab for a classroom demonstration, and as an online practice site where each try is checked atom by atom.
Frequently Asked Questions
Is there a game for balancing chemical equations?
Yes. The Play tab on this page is a free balancing chemical equations game with 36 stages from counting atoms to AP Chemistry redox, a Daily Balance and a 90-second Speed Lab. Press React! and every atom flies to its place in the products, so you can see whether the equation is balanced. It needs no sign-up.
What is a good website to practice balancing chemical equations?
Use one that checks each attempt and explains what is wrong. On this page the game marks every try, the atom ledger shows which element is off, the hints follow the inspection method, and the Quiz tab gives a self-marking practice test. It covers 60+ reactions at middle school, high school and AP level.
Can you give me a random chemical equation to balance?
Yes. Start a Speed Lab round or the Daily Balance on this page and it serves random equations from a library of 60+ reactions. For one to try right now: Fe + O₂ → Fe₂O₃. The answer is 4Fe + 3O₂ → 2Fe₂O₃.
How do I know if a chemical equation is balanced?
Count the atoms of every element on both sides, multiplying each subscript by the coefficient in front of its formula. The equation is balanced only if every element has the same count on both sides. For example, 2H₂ + O₂ → 2H₂O has 4 H and 2 O on each side.
What does the 3 in front of O₂ mean?
It is a coefficient: it means three separate O₂ molecules, which is six oxygen atoms in total. It does not mean that six oxygen atoms are bonded together in one molecule.
How do you balance equations with polyatomic ions?
If a polyatomic ion such as SO₄ or NO₃ appears unchanged on both sides, balance it as one unit instead of counting its sulfur and oxygen separately. For example, in Al₂(SO₄)₃ + NaOH → Al(OH)₃ + Na₂SO₄, balance the three SO₄ groups first: 1, 6, 2, 3.
How do you balance a chemical equation step by step?
Write correct formulas, count the atoms of each element on both sides, then add coefficients: metals first, other non-metals next, hydrogen and oxygen last. Reduce the coefficients to the smallest whole numbers and never change a subscript. For example, H₂ + O₂ → H₂O becomes 2H₂ + O₂ → 2H₂O.
Is there a calculator that balances chemical equations with steps?
Yes. Type the equation into the Balancer tab on this page and open Show step-by-step working. It shows the atom count, the inspection method one element at a time, the algebraic method with one equation per element, and a check table. It is free and needs no sign-up.
How do you balance a chemical equation using the algebraic method?
Give each formula a letter (a, b, c …), write one equation per element so that the atoms on the left equal the atoms on the right, set one letter to 1 and solve. Multiply by the lowest common denominator to clear any fractions. For Fe₂O₃ + CO → Fe + CO₂ this gives 1, 3, 2, 3.
Which element should you balance first?
Start with an element that appears in only one formula on each side, usually a metal, then the other non-metals, and leave hydrogen and oxygen until last because they appear in many formulas. If a polyatomic ion such as SO₄ appears unchanged on both sides, it can be balanced as one unit.
Can you balance an equation with fractions?
Yes, as a working step. For ethane, C₂H₆ + (7/2)O₂ → 2CO₂ + 3H₂O balances the atoms, but a final equation uses whole numbers, so multiply every coefficient by 2: 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O.
What is the difference between a coefficient and a subscript?
A coefficient is the large number in front of a formula and multiplies the whole molecule, like the 2 in 2H₂O. A subscript is the small number inside a formula and counts the atoms of one element in a single molecule. You balance only with coefficients.
Why can't I change subscripts to balance an equation?
Because a subscript is part of the substance's identity. Changing H₂O to H₂O₂ turns water into hydrogen peroxide, so the equation would describe a different reaction. Only coefficients, which count how many units react, may change.
Why must chemical equations be balanced?
Because of the law of conservation of mass: atoms are only rearranged in a reaction, so each element must have the same number of atoms on both sides. A balanced equation also gives the mole ratios used in stoichiometry.
How do you balance combustion equations?
Balance carbon first by matching CO₂ to the carbons in the fuel, then hydrogen by matching H₂O, and oxygen last. If oxygen comes out odd, use a fraction and double everything. Example: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O.
Can the balancer handle brackets and hydrates like Ca(OH)₂ and CuSO₄·5H₂O?
Yes. Brackets multiply everything inside them, nested brackets work, and a full stop or middle dot joins water of crystallisation. Ionic charges and electrons are not supported yet.
Who Uses This Balancing Equations Game?
Students in middle school, high school, honors and AP Chemistry use it to learn balancing before stoichiometry and to check homework with the working shown. It covers the same skill for GCSE, IGCSE, A-Level and IB Chemistry. Teachers and tutors use the live canvas as a classroom demonstration and the game and Quiz as self-marking homework. It is free, needs no account and runs in the browser on any phone, tablet or laptop.
Explore Related Free Chemistry & Science Simulators
Build on what you learn here with other free simulators on MechSimulator. See how atoms join with the Chemical Bonds Simulator, build elements electron by electron in the Build an Atom Simulator, and test acids and alkalis with the Litmus Paper Test Virtual Lab. Explore gas behaviour with the Ideal Gas Law Simulator, mix acids and bases in the Acids & Bases Mixing Simulator, or put stoichiometry to work in the Titration Simulator. All tools are free, browser-based and need no sign-up or installation. Then see redox reactions drive an electric current in the Galvanic & Electrolytic Cell Virtual Lab.
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