Balancing Chemical Balancing Chemical EquationsEquations

Unit 6Unit 6

Using the Law of Using the Law of ConservationConservation

The # of atoms of each element on The # of atoms of each element on the reactants side of a chemical eqn the reactants side of a chemical eqn MUST equal the # of atoms of each MUST equal the # of atoms of each element on the products side.element on the products side.

We use numbers called We use numbers called COEFFICIENTS to balance both sides COEFFICIENTS to balance both sides of the reaction.of the reaction.

ExamplesExamples HH22 (g) + Cl (g) + Cl22 (g) (g) → HCl (g)→ HCl (g) HH22 (g) + Cl (g) + Cl22 (g) (g) → → 22HCl (g)HCl (g)

HH22O (l) → HO (l) → H22 (g) + O (g) + O22 (g) (g) 22HH22O (l) → O (l) → 22HH22 (g) + O (g) + O22 (g) (g)

CC33HH8 8 (l) + O(l) + O22 (g) → CO (g) → CO22 (g) + H (g) + H22O (g)O (g) CC33HH8 8 (l) +(l) + 55OO22 (g) → (g) → 33COCO22 (g) + (g) + 4 4HH22O (g)O (g)

HH22SOSO44 (aq) + Ca(OH) (aq) + Ca(OH)22 (s) → H (s) → H22O (l) + CaSOO (l) + CaSO44 (aq)(aq)

HH22SOSO44 (aq) + Ca(OH) (aq) + Ca(OH)22 (s) → (s) → 22HH22O (l) + CaSOO (l) + CaSO44 (aq)(aq)