Answer: Ash is the solid, somewhat powdery substance that is left over after any fuel undergoes combustion. Broadly speaking, coal ash and wood ash are the two most talked-about types of ash, although the ash is created during any process of incomplete combustion.
How ash is formed?
Ash occurs naturally from any fire that burns vegetation—ignited by lightning, volcanic activity, or other processes. Ashes may eventually disperse in the soil to make it fertile or may remain intact under soil for a long time—even long enough to turn into coal.
When wood is burned new substances are produced?
Wood changes chemically to carbon dioxide when it burns and leaves a residue of ashes. These ashes cannot be changed back to wood. When air and water act on an object made of iron, a new substance, rust, is formed. Rust is a different substance than iron.
What indicates a new substance has been formed?
Yes; new substances formed, as evidenced by the color changes and bubbles. Some signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color change, formation of a precipitate, formation of a gas, odor change, temperature change.