9781422280492

Salt

and they can have different tastes. For example, a type of toxic salt used to make bleach is called potassium dichromate, which is orange in color. Potassium bitartrate, a salt that forms in wine casks and is also known as cream of tartar, doesn’t taste “salty” at all—it has a sour flavor. Some salts even have particular odors, depending on their chemical makeup. All these salts have their uses, but by far the most common is sodium chloride, or table salt, the stuff we use to season and preserve our food. Sodium chloride is a compound formed by a reaction between hydrochloric acid (an acid) and sodium hydroxide (a base). In the reaction, sodium and chlorine atoms create strong ionic bonds. The bonds make a three-dimensional lattice , which gives salt its characteristic crystalline structure. The reaction also produces water. You may sometimes see sodium chloride written as NaCl; that’s its chemical formula. The “Na” is the chemical abbreviation for the element sodium, and the “Cl” stands for chlorine. Chloride is the name for chlorine that has an electric charge. A mind-bending fact is that, separately, both sodium (a metal) and chlorine (a gas) are toxic to humans, yet when they bond, they create something we ingest every day! S alt in N ature Sodium chloride is found in nature in many forms. One is its mineral form, called halite or rock salt. Large deposits of halite exist underground on every continent on earth. It is also found as an evaporite around salt lakes. These are lakes formed when mineral- and salt-rich water f lows into a lake that is “closed,” which means it has no way of draining. When this water evaporates in the sun, salts and minerals are left behind. In some arid desert climates, ancient lakes have evaporated completely over thousands of years. All that remains are vast stretches of salts and minerals called salt flats or salt pans. One of the most famous salt flats in the world is the Bonneville Salt Flats in Utah, which was created by the evaporation of the Pleistocene-era Lake

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