Balancing Equations

Law of Conservation of Mass The Law of Conservation of Mass states: that mass is neither created nor destroyed in any chemical reaction. Therefore balancing equations requires the same number of atoms on both sides of a chemical reaction. The number of atoms in the Reactants must equal the Number of atoms in the Products

Balance elements in the following order: Nonmetals Metals Polyatomic ions Hydrogen Oxygen

Polyatomic Ions When balancing polyatomic ions treat them as one unit if they appear on both sides of the equation.

Balancing Equations N2 + H2 NH3 __N__ 2 1 __H__ 2 3 Complete an atom inventory. 2 1 2 3 __N__ __H__

Balancing Equations N2 + H2 2NH3 Nothing is balanced. Balance the nitrogen first by placing a coefficient of 2 in front of the NH3. N2 + H2 2NH3

Balancing Equations N2 + 3H2 2NH3 2 2 6 6 __N__ __H__ Hydrogen is not balanced. Place a 3 in front of H2. N2 + 3H2 2NH3 Complete a final atom inventory. 2 2 6 6 __N__ __H__

Balancing Equations C3H8 + O2→ CO2+ H2O __C__ 3 1 __H__ 8 2 __O__ 2 3 Complete an atom inventory. 3 1 8 2 2 3 __C__ __H__ __O__

Balancing Equations C3H8 + O2 → 3CO2+ H2O Nothing is balanced. Balance the carbon first by placing a coefficient of 3 in front of the CO2. C3H8 + O2 → 3CO2+ H2O

Balancing Equations C3H8 + O2 → 3CO2+ 4H2O Now balance the hydrogen by placing a 4 in front of the water on the products side. C3H8 + O2 → 3CO2+ 4H2O

Balancing Equations C3H8 + 5O2 → 3CO2+ 4H2O __C__ 3 3 __H__ 8 8 __O__ Balance the oxygen on the reactants side with a coefficient of 5. C3H8 + 5O2 → 3CO2+ 4H2O Complete a final atom inventory. 3 3 8 8 10 10 __C__ __H__ __O__

Balancing Equations BF3+ Li2SO3→ B2(SO3)3+ LiF 1 2 3 1 2 1 1 3 __B__ Complete an atom inventory. 1 2 3 1 2 1 1 3 __B__ __F__ __Li__ __SO3__

Balancing Equations BF3+ Li2SO3→ B2(SO3)3+ 3LiF Nothing is balanced. Balance the fluorine first by placing a coefficient of 3 in front of the LiF. BF3+ Li2SO3→ B2(SO3)3+ 3LiF

Balancing Equations 2BF3+ Li2SO3→ B2(SO3)3+ 3LiF Now balance the boron by placing a 2 in front of the BF3 on the reactants side. 2BF3+ Li2SO3→ B2(SO3)3+ 3LiF Notice we’ve unbalanced the fluorine, and now must adjust our coefficients.

Balancing Equations 2BF3+ Li2SO3→ B2(SO3)3+ 6LiF Now balance the boron by placing a 2 in front of the BF3 on the reactants side. 2BF3+ Li2SO3→ B2(SO3)3+ 6LiF Notice we’ve unbalanced the fluorine, and now must adjust our coefficients.

Balancing Equations __B__ 2BF3+ 3Li2SO3→ B2(SO3)3+ 6LiF 2 2 __F__ 6 6 Balance the lithium sulfite on the reactants side with a coefficient of 3. 2BF3+ 3Li2SO3→ B2(SO3)3+ 6LiF Complete a final atom inventory. __B__ __F__ __Li__ __SO3__ 2 2 6 6 3 3

YOU ARE BALANCED!!