Chemical equations
Type formulas joined by +, the two sides by ->, or choose an example. The page balances it and counts each element's atoms on both sides.
Write and balance
Write and balance
Write formulas with element symbols, for example CH4 + O2 -> CO2 + H2O; brackets such as Ca(OH)2 and states such as (g) are allowed. To check your own balance, type the coefficients in front of the formulas.
A balanced equation only counts atoms: it does not show whether the reaction happens, how fast, or under what conditions.
Balance it yourself
Six real school reactions. Type a coefficient in each box (an empty box counts as 1); a wrong answer shows, element by element, where the atoms do not match.
Use it in class
The worksheet and the board get exactly what is set now. You can edit the worksheet before printing, and its answer key comes on a separate page. On the board everything stays editable, and nothing is added to a live lesson.
How to use it
- Type an equation or choose an example; the page reads each formula and refuses what it cannot handle, saying why.
- The balanced equation appears with the smallest whole-number coefficients, and the table counts each element's atoms on both sides.
- To check a balance, type the coefficients in front of the formulas (2H2 + O2 -> 2H2O): the page says whether each element matches.
- For class: print equations to balance, with the coefficients on a separate key page, or put an equation on the board, balanced or with empty boxes.
Worked examples
Balancing H2 + O2 -> H2O
Count the atoms: 2 oxygen atoms on the left, 1 on the right, so put 2 in front of H2O. Now there are 4 hydrogen atoms on the right and 2 on the left, so put 2 in front of H2: 2H2 + O2 → 2H2O. Each element now has as many atoms on both sides.
Balancing CH4 + O2 -> CO2 + H2O
Carbon is already balanced (1 and 1). Hydrogen: 4 on the left, so 2 in front of H2O. Oxygen: now 2 + 2 = 4 on the right, so 2 in front of O2: CH4 + 2O2 → CO2 + 2H2O. Leave the element that appears in several substances, here oxygen, for last.
Quick reference
- A coefficient multiplies a whole formula; a subscript belongs to the element (or bracket) just before it.
- Balancing changes only the coefficients, never the formulas: H2O stays H2O.
- Atoms are neither made nor destroyed in a reaction, so each element has as many atoms on both sides.
- The coefficients are the smallest whole numbers that balance the equation; a coefficient of 1 is not written.
- Reactants
- Products
- Coefficient: the number in front of a formula
- Subscript: the small number after a symbol
- Balanced equation: as many atoms of each element on both sides
- Conservation of mass: atoms are not made or destroyed
- States: (s) solid, (l) liquid, (g) gas, (aq) in water
Sources
The reactions and terms were checked against the school textbooks and references below. The page computes every balance itself, exactly, and checks it by counting atoms; automated tests compare it with a separate calculation.