Chloride generally has a high melting point and boiling point (ammonium chloride will "sublimate"). The melting and boiling points and related properties of some common chlorides are shown in Table 1. When some metals (such as gold) are dissolved in aqua regia, an acid called chloroauric acid (such as chloroauric acid), nitric oxide and water will be produced. The most common chloride is sodium chloride, which is the main component of table salt. Its chemical formula is NaCl. Sodium chloride is widely used. Its electrolysis produces chlorine, hydrogen and sodium hydroxide, and chlorine and hydrogen are used to prepare hydrochloric acid. And sodium chloride and calcium chloride are melted and electrolyzed to prepare metal sodium; Sodium chloride is also the raw material for soda ash production by ammonia alkali.