IIIIIIIVV Balancing Equations Ch. 8 – Chemical Reactions

A. Balancing Steps 1.Write the unbalanced equation. 2. Count atoms on each side of the arrow. 3. Put in coefficients to make #s of atoms for each element equal on both sides of the arrow. Do not change any subscript!!! Coefficient  subscript = # of atoms 4.Reduce coefficients to lowest possible ratio, if necessary. 5.Double check atom balance!!!

B. Helpful Tips n Balance one element at a time. n Update ALL atom counts after adding a coefficient. n If an element appears more than once per side, balance it last. n Balance polyatomic ions as single units.  “1 SO 4 ” instead of “1 S” and “4 O”

Al + CuCl 2  Cu + AlCl 3 Al Cu Cl 2  3  6   C. Balancing Example Aluminum and copper(II) chloride react to form copper and aluminum chloride. 2  2  6

Balance the following equations: 1.) Fe 2 O 3 + H 2  Fe + H 2 O 6    6 Fe O H 

Ag NO 3 H S 2.) AgNO 3 + H 2 S  Ag 2 S + HNO 3 2  2 2 

Problems (cont.) 3.) Zn(OH) 2 + H 3 PO 4  Zn 3 (PO 4 ) 2 +H 2 O 4.) SO 2 + O 2  SO 3 5.) MnO 2 + HCl  MnCl 2 + H 2 O + Cl 2