Formation of Acids and Bases
from Metallic & Nonmetallic Oxides

Formation of a Base

1. Metals will react with oxygen to produce metallic oxides. The oxides are usually a white smoke which will dissolve in water to form a BASE. Remember from the experiment; the indicator turned BLUE.

   The general reaction for metal X is:
   

   X + O₂ -----> X₂O_n
   {where n is the valence of the metal}
   And the oxide then dissolves in water as follows: X₂O_n + H₂O ------> X(OH)_n + H₂
   The metal hydroxide is the base.

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   Formation of an Acid

2. Nonmetals react the same way with oxygen; an exothermic reaction results, with either smoke or a gas being produced. This product also reacts with water however an ACID results. Remember from the experiment; the indicator turns YELLOW.

   The general reaction for a nonmetal Y is:
   

   Y + O₂ ----> Y₂O_n
   {where n is the valence of the nonmetal} And the oxide then dissolves in water as follows: Y₂O_n + H₂O -------> H_aYO_n+1
   In the acid formula ( H_aYO_n+1), the "a" is the valence of the polyatomic nonmetal ion YO_n+1.

   This is the main chemical difference between a metal and a nonmetal: the reaction of their oxide with water.

   METAL ------> oxide BASIC in water.

   NONMETAL -----> oxide ACIDIC in water.

   This is the problem when nonmetals such as sulfur and nitrogen are oxidized; these oxides react with water in the atmosphere to generate acid rain.