Balancing Chemical Equations  

 1.  LEARN THESE DIATOMIC MOLECULES:  O₂  H₂  N₂  F₂  Cl₂  Br₂  I₂

 2.  The same number of atoms of each element appearing in reactants must  appear in the products.

 3.  The subscripts of a formula cannot be changed to balance the equation. Each compound must retain its stableness via oxidation states.

 4.  Choose compound with greatest number of atoms first.

 5.  Balance by placing necessary coefficients in front of entire molecules.       NO SUBSCRIPT CHANGES!

 6.  Be certain each side of equation has same number of atoms of each type.

 7.  Make sure coefficients are in lowest whole number ratios.

 8.  Polyatomic ions usually stay intact, but multiple polyatomic ions  may be separated.

    (aq.) stands for aqueous which is Latin for water solution 

          (g)  gas      (l) liquid     (s)  solid       (c) crystalline solid

   example problem:

                  C₈H₁₈    +    O₂    -->     CO₂   +     H₂O

                  C₈H₁₈    +    O₂    -->  __ CO₂   +  __ H₂O

                  C₈H₁₈    + __ O₂    -->  __ CO₂   +  __ H₂O

               __ C₈H₁₈    + __ O₂    -->  __ CO₂   +  __ H₂O

      Balancing Equation Problems

   1)       H₂CrO₄  +  AgNO₃    -->    Ag₂CrO₄  +  HNO₃

 2)       P₄  + O₂  + H₂O    -->   H₃PO₄

3)       Th(NO₃)₄   +  K₃PO₄    -->    Th₃(PO₄)₄   +  KNO₃

 4)       ZnCO₃  +  HNO₃   -->   Zn(NO₃)₂  +  CO₂   +   H₂O

 5)       Li₂O₂   +   H₂O   -->   LiOH   +   O₂

6)       Cu(NO₃)₂   -->   CuO   +  NO₂   +  O₂

 7)       NH₄NO₃  +   Ca(OH)₂   -->   Ca(NO₃)₂   +  NH₃   +    H₂O

 8)       Al  +  HCl  -- >    AlCl₃   +   H₂

 9)       C₂H₂   +  O₂  -- >   CO₂   +   H₂0

 10)      PbS   +   O₂   -->   PbO   +   SO₂

 11)      MgO   +   HBr   -->  MgBr₂   +  H₂O

 12)      KClO₃   -->   KCl   +  O₂

 13)      Mg   +  HCl   -->   H₂   +   MgCl₂

 14)      AlBr₃   +   Cl₂    -->   AlCl₃   +   Br₂

 15)      Pb(NO₃)₂  +  KI   -->   PbI₂   +   KNO₃

16)      KClO₄   -->   KCl   +  O₂

 17)      Na₃PO₄   +  BaCl₂   -->   Ba₃(PO₄)₂    +   NaCl

 18)      Ba(NO₃)₂  +  Na₃PO₄   -->  Ba₃(PO₄)₂   +  NaNO₃

 19)  aluminum bromide + chlorine gas --> aluminum chloride + bromine gas

 20)  sodium permanganate  + sulfuric acid  -->  sodium sulfate  +  manganese (VII) oxide   +  water

 21)  magnesium hydroxide  +  calcium hydrogen phosphate   -->  calcium hydroxide  +  magnesium hydrogen phosphate

22)  sulfur trioxide + nitric acid  -->  sulfuric acid  + nitrogen (V) oxide

 23)  manganese (IV) oxide + hydrogen chloride --> manganese (II) chloride  +  water  +  chlorine gas