Sodium Chloride (Salt)

Sodium chloride or common salt is the chemical compound NaCl. Salt occurs naturally in many parts of the world as the mineral halite and as mixed evaporites in salt lakes. Seawater has lots of salt; it contains an average of 2.6% (by weight) NaCl, or 26 million metric tons per cubic kilometer (120 million short tons per cubic mile), an inexhaustible supply (note: seawater also contains other dissolved solids; salt represents about 77% of the total dissolved solids).

Salt is important in many ways. It is an essential part of the diet of both humans and animals and is a part of most animal fluids, such as blood, sweat, and tears. It aids digestion by providing chlorine for hydrochloric acid, a small but essential part of human digestive fluid. Persons with hypertensive heart disease often must restrict the amount of salt in their diet.

NaCl consists of cubic close packed chloride (negative ions - yellow) with sodium (positive ions - red).

Salt is widely used as a seasoning for foods and is used in curing meats and preserving fish and other foods. Iodized table salt usually contains small amounts of potassium iodide, sodium carbonate, and sodium thiosulfate. As a chemical salt is used in making glass, pottery, textile dyes, and soap.

Sodium chloride is readily soluble in water and insoluble or only slightly soluble in most other liquids. It forms small, transparent, colorless to white cubic crystals. Sodium chloride is odorless but has a characteristic taste. It is an ionic compound, being made up of equal numbers of positively charged sodium and negatively charged chloride ions.

Curriculum Resources:

Salt Institute: Salt: The Essence of Life (A Multidisciplinary Curriculum)
Morton^® Salt: A Graphic Timeline of the History of Morton^® Salt
Morton^® Salt: Household Hints
Crystal Growing Activity (pdf) and remember Safety First!

Milli's Safety Tips

American Chemical Society: Office of Community Activities

Always:

• Work with an adult.
  
• Read and follow all directions for the activity.
  
• Read all warning labels on all materials being used.
  
• Wear eye protection.
  
• Follow safety warnings or precautions, such as wearing gloves or tying back long hair.
  
• Use all materials carefully, following the directions given.
  
• Be sure to clean up and dispose of materials properly when you are finished with an activity.
  
• Wash your hands well after every activity.

Never eat or drink while conducting an experiment, and be careful to keep all of the materials used away from your mouth, your nose, and your eyes!

For more detailed information on safety please refer to the NCW Safety Guidelines.

Further Reading:

Salt: A World History by Mark Kurlansky (ISBN: 0802713734)

Salt: Grain of Life by Pierre Laszlo, Mary Beth Mader (Translator) (ISBN: 0231121989)