The main cause of chemical burns is from contact with strong acids or bases. The strength of acids and bases is defined by the pH scale, which ranges from 1-14. A very strong acid has a pH of 1 and may cause a severe burn. A very strong base has a pH of 14 and may also cause a severe burn. A substance with a pH of 7 is considered neutral and does not burn. Chemical burns from acids or bases are also referred to as caustic burns.