Balancing Equations

Reactions: reactants  products We say “reactants yield products.”

Memory Lane: ie: What we start with, we must end with. Remember – The law of conservation of mass?! “In a chemical reaction, mass cannot be created or destroyed.” ie: What we start with, we must end with.

Is mass conserved in this reaction? Conservation of Mass?! Na + Cl2  NaCl Is mass conserved in this reaction?

SUBSCRIPTS and COEFFICIENTS 2Na + Cl2  2NaCl COEFFICIENTS SUBSCRIPTS

BALANCING: Step #1: Take inventory.

BALANCING: Step #2: Attack

BALANCING: Step #3: Re-inventory

BALANCING: Step #4: Re-attack

BALANCING: Step #6: Repeat

Why is there a 2?! DIATOMIC Di = 2 atom = atom Na + Cl2  NaCl Draw the Lewis Structure for Cl2 DIATOMIC Di = 2 atom = atom

TRICKS: Save lone elements for last Group polyatomics for easier inventory Typically saving oxygen and hydrogen for last is easier