Nonmetallic oxides behave as acidic compounds, as they react with bases to form salts and water, analogous to the reaction of acids with bases.

Carbon dioxide reacts with calcium hydroxide to produce a salt and water.

Metallic oxides are described as basic oxides due to their ability to react with acids to produce salts and water.

The general reaction between a metal oxide and an acid is the formation of a salt and water.

The formation of copper(II) chloride during the reaction causes the blue-green color.