Chemical Reactions and Equations

Chemical Changes and Reactions

A chemical reaction occurs whenever matter undergoes a chemical change, altering the nature and identity of the initial substance. Everyday processes that indicate a chemical reaction has taken place include milk being left at room temperature during summers, an iron tawa, pan, or nail being left exposed to a humid atmosphere, grapes getting fermented, food being cooked, food getting digested in the body, and respiration.

Oxidation of Magnesium

The burning of magnesium demonstrates a chemical reaction in which a magnesium ribbon about $3\text{-}4\text{ cm}$ long is cleaned by rubbing with sandpaper, held using a pair of tongs, and burned over a spirit lamp or burner. The ash collected in a watch-glass during this process is magnesium oxide, which is formed by the reaction of magnesium with air.