Balanced Chemical Equations

Conservation of Matter Matter can neither be created nor destroyed by any physical or chemical change. Atoms that start a reaction must still be present at the end of the reaction.

Chemical Equations Chemical equations show which substances appear at the beginning and end of a reaction and how many of each of them are present.

Chemical Notation Recall that coefficients multiply an entire species and subscripts multiply a specific element in a compound.

Chemical Notation Symbo l Meaning+ separates multiple reactants or products → separates reactants from products (s) indicates solid state (l) indicates liquid state (g) indicates gaseous state (aq) indicates species in water solution

Balancing Equations 1) Write the substances you start with (reactants) to the left and the substances you end with (products) to the right of the arrow. Example: Solid aluminum and chlorine gas combine to form solid aluminum chloride at 298K.

Balancing Equations 2) Separate reactants and products with a line, then write the count of each atom below each compound. Example: Solid aluminum and chlorine gas combine to form solid aluminum chloride at 298K. Al = 1 Cl = 2 Al = 1 Cl = 3

Balancing Equations 3) Compare each atom on each side. If not equal, add coefficients. Example: Solid aluminum and chlorine gas combine to form solid aluminum chloride at 298K. Al = 1 Cl = 2 Al = 1 Cl =