Combustion, or , is an example of one of the most familiar chemical changes. The melting of ice, likewise, is one of the most common examples of physical changes. When a piece of coal burns, Response area combines with the carbon in the coal. The products are carbon dioxide gas, water vapor, and a lot of ash. After careful measurements are taken, the Response area of the reactants (coal and oxygen) is Response area to the mass of the products (carbon dioxide, water vapor, and ash).