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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.
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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__ __H__ • 2 1 • 2 3 • Complete an atom inventory.
Balancing Equations • Nothing is balanced. • Balance the nitrogen first by placing a coefficient of 2 in front of the NH3. N2 + H22NH3
Balancing Equations • Hydrogen is not balanced. • Place a 3 in front of H2. • Complete a final atom inventory. N2 + 3H22NH3 • 2 2 • 6 6 __N__ __H__
Balancing Equations C3H8 + O2→ CO2+ H2O __C__ __H__ __O__ • 3 1 • 8 2 • 2 3 • Complete an atom inventory.
Balancing Equations • Nothing is balanced. • Balance the carbon first by placing a coefficient of 3 in front of the CO2. C3H8 + O2 → 3CO2+ H2O
Balancing Equations • Now balance the hydrogen by placing a 4 in front of the water on the products side. C3H8 + O2 → 3CO2+ 4H2O
Balancing Equations • Balance the oxygen on the reactants side with a coefficient of 5. C3H8 + 5O2 → 3CO2+ 4H2O • Complete a final atom inventory. __C__ __H__ __O__ • 3 3 • 8 8 • 10 10
Balancing Equations BF3+ Li2SO3→ B2(SO3)3+ LiF • 12 • 31 • 21 • 1 3 __B__ __F__ __Li__ __SO3__ • Complete an atom inventory.
Balancing Equations • 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 • Now balance the boron by placing a 2 in front of the BF3on the reactants side. 2BF3+ Li2SO3→ B2(SO3)3+ 3LiF • Notice we’ve unbalanced the fluorine, and now must adjust our coefficients.
Balancing Equations • Now balance the boron by placing a 2 in front of the BF3on the reactants side. 2BF3+ Li2SO3→ B2(SO3)3+ 6LiF • Notice we’ve unbalanced the fluorine, and now must adjust our coefficients.
Balancing Equations • 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__ • 22 • 66 • 66 • 3 3