Examples of 10 Balanced Chemical Equations

See How To Write Balanced Equations

Chemical equations
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By
Anne Marie Helmenstine, Ph.D.
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
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Updated on October 02, 2019

Writing balanced chemical equations is essential for chemistry class. Here are examples of balanced equations you can review or use for homework. Note that if you have "1" of something, it does not get a coefficient or subscript. The word equations for a few of these reactions have been provided, though most likely you'll be asked to provide only the standard chemical equations.

Key Takeaways: Examples of Balanced Equations

  • In chemistry, it's important to be able to recognize when equations are balanced, when they are not balanced, and how to balance them.
  • A balanced equation contains the same number of each type of atoms on both the left and right sides of the reaction arrow.
  • To write a balanced equation, the reactants go on the left side of the arrow, while the products go on the right side of the arrow.
  • Coefficients (number in front of a chemical formula) indicate moles of a compound. Subscripts (numbers below an atom) indicate the number of atoms in a single molecule.
  • To calculate the number of atoms, multiply the coefficient and the subscript. If the atom appears in more than one reactant or product, add together all the atoms on each side of the arrow.
  • If there is only one mole or one atom, then the coefficient or subscript "1" is implied, but is not written.
  • A balanced equation is reduced to the lowest whole number coefficients. So, if all the coefficients can be divided by 2 or 3, do this before finalizing the reaction.

6 CO2 + 6 H2O → C6H12O6 + 6 O2 (balanced equation for photosynthesis)
6 carbon dioxide + 6 water yields 1 glucose + 6 oxygen

2 AgI + Na2S → Ag2S + 2 NaI
2 silver iodide + 1 sodium sulfide yields 1 silver sulfide + 2 sodium iodide

Ba3N2 + 6 H2O → 3 Ba(OH)2 + 2 NH3

3 CaCl2 + 2 Na3PO4 → Ca3(PO4)2 + 6 NaCl

4 FeS + 7 O2 → 2 Fe2O3 + 4 SO2

PCl5 + 4 H2O → H3PO4 + 5 HCl

2 As + 6 NaOH → 2 Na3AsO3 + 3 H2

3 Hg(OH)2 + 2 H3PO4 → Hg3(PO4)2 + 6 H2O

12 HClO4 + P4O10 → 4 H3PO4 + 6 Cl2O7

8 CO + 17 H2 → C8H18 + 8 H2O

10 KClO3 + 3 P4 → 3 P4O10 + 10 KCl

SnO2 + 2 H2 → Sn + 2 H2O

3 KOH + H3PO4 → K3PO4 + 3 H2O

2 KNO3 + H2CO3 → K2CO3 + 2 HNO3

Na3PO4 + 3 HCl → 3 NaCl + H3PO4

TiCl4 + 2 H2O → TiO2 + 4 HCl

C2H6O + 3 O2 → 2 CO2 + 3 H2O

2 Fe + 6 HC2H3O2 → 2 Fe(C2H3O2)3 + 3 H2

4 NH3 + 5 O2 → 4 NO + 6 H2O

B2Br6 + 6 HNO3 → 2 B(NO3)3 + 6 HBr

4 NH4OH + KAl(SO4)2·12H2O → Al(OH)3 + 2 (NH4)2SO4 + KOH + 12 H2O

Check Equations to Make Sure They Are Balanced

  • When you balance a chemical equation, it's always a good idea to check the final equation to make sure it works out. Perform the following check:
  • Add up the numbers of each type of atom. The total number of atoms in a balanced equation will be the same on both sides of the equation. The Law of Conservation of Mass states the mass is the same before and after a chemical reaction.
  • Make sure you accounted for all types of atoms. Elements present on one side of the equation need to be present on the other side of the equation.
  • Make sure you can't factor out the coefficients. For example, if you could divide all of the coefficients on both sides of the equation by 2, then you may have a balanced equation, but not the simplest balanced equation.

Sources

  • James E. Brady; Frederick Senese; Neil D. Jespersen (2007). Chemistry: Matter and Its Changes. John Wiley & Sons. ISBN 9780470120941.
  • Thorne, Lawrence R. (2010). "An Innovative Approach to Balancing Chemical-Reaction Equations: A Simplified Matrix-Inversion Technique for Determining the Matrix Null Space". Chem. Educator. 15: 304–308.
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Helmenstine, Anne Marie, Ph.D. "Examples of 10 Balanced Chemical Equations." ThoughtCo, Apr. 5, 2023, thoughtco.com/examples-of-10-balanced-chemical-equations-604027. Helmenstine, Anne Marie, Ph.D. (2023, April 5). Examples of 10 Balanced Chemical Equations. Retrieved from https://www.thoughtco.com/examples-of-10-balanced-chemical-equations-604027 Helmenstine, Anne Marie, Ph.D. "Examples of 10 Balanced Chemical Equations." ThoughtCo. https://www.thoughtco.com/examples-of-10-balanced-chemical-equations-604027 (accessed April 25, 2024).