What information is contained in a chemical equation?

After carefully writing an equation, making certain the formulas are correct, and seeing that it is balanced, what does it tell you?
  • A chemical equation will tell you the formulas and symbols of the reactants and products.
  • A chemical equation can show the physical state of a substance, whether it is a solid, liquid, gas, or in solution.
  • A chemical equation can show if special conditions are required for a reaction to take place, such as adding heat or using a catalyst.
  • And, if the equation is balanced: The coefficient numbers in the equation show the number of molecules, formula units, or atoms of the species involved in the reaction. The coefficients also equal the number of moles of each reactant and product.

It is this last statement that reveals how an equation becomes a powerful quantitative statement. Balancing an equation generates the set of coefficients that equal the number of moles of each species. Once the mole relationships between reactants and products are known, calculations concerning amounts of reactant consumed or products formed are possible.