Sodium Chloride
Definition and meaning of Sodium Chloride in chemistry.
Sodium chloride, commonly known as salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium ions and chloride ions. It is the salt most responsible for the salinity of seawater and of the extracellular fluid of many multicellular organisms. In its edible form of table salt, it is commonly used as a condiment and food preservative.
In more detail
In the solid state, sodium chloride forms a giant ionic crystalline lattice where each sodium ion (Na+) is surrounded by six chloride ions (Cl-), and each chloride ion is surrounded by six sodium ions in a face-centered cubic arrangement. This strong electrostatic attraction between oppositely charged ions gives the compound a high melting point and makes it highly brittle. It is highly soluble in polar solvents like water, where the lattice dissociates entirely, and the free-moving solvated ions render the solution electrically conductive. Sodium chloride is produced on a massive scale by the evaporation of seawater or brine from brine wells and salt lakes, as well as by mining halite rock salt. Industrially, it is the primary source of sodium and chlorine compounds, serving as the feedstock for the chlor-alkali process to produce chlorine gas and sodium hydroxide. In biological systems, sodium chloride is critical for maintaining fluid balance, nerve impulse transmission, and muscle contraction.
Key facts
| Field | Inorganic Chemistry |
|---|---|
| Formula | NaCl |
| Molar mass | 58.44 g/mol |
| Crystal structure | Face-centered cubic |
| Melting point | 801 °C |
During winter, rock salt is frequently spread on icy roads because dissolved sodium chloride lowers the freezing point of water, melting ice in a process called freezing-point depression.
Frequently asked questions
Why does solid sodium chloride not conduct electricity?
In the solid state, the ions are locked into a rigid crystalline lattice and cannot move; it only conducts electricity when melted or dissolved in water, allowing the Na+ and Cl- ions to move freely.
How does salt preserve food?
Salt draws water out of microbial cells through osmosis, dehydrating the bacteria and fungi that cause food spoilage, thereby inhibiting their growth.