Writing and Balancing Chemical Equations

Law of Conservation of Matter Matter can neither be created nor destroyed In a chemical equation, you must have the same number of each atom on each side of the equation

Coefficients Numbers placed in front of a substance Coefficients are “distributed” over each atom of the molecule Ex.: 2H2O = 4H, 2O

Diatomic Molecules Certain elements come in molecules of two atoms apiece…these are called diatomic H2, N2, O2, F2, Cl2, Br2, I2 “H BrONClIF”

Steps for Writing Chemical Equations 1. Write the reactants on the left side of the arrow and the products on the right. 2. Balance the equation using coefficients Start with the most complicated molecule Put coefficients in front of molecules NEVER change a subscript when balancing 3. Make sure your final set of coefficients are whole numbers with no common factors other than one (can’t be reduced)

Examples 1. H2 + O2  H2O 2. N2O5 + H2O  HNO3 3. Fe + O2  Fe2O3 4. KClO3  KCl + O2 5. C + H2O  CO + H2

Remember…A balanced equation must have equal numbers of each type of atom on both sides of the arrow