Sodium Chloride (Table Salt) (NaCl) — Properties, Uses & Safety

Overview

Sodium chloride (NaCl), commonly known as table salt, is one of the most familiar chemical compounds in everyday life. It has a molar mass of 58.44 g/mol and appears as a white crystalline solid at room temperature. Sodium chloride is the classic example of an ionic compound, formed when a sodium atom transfers its single valence electron to a chlorine atom, creating Na⁺ and Cl⁻ ions held together by strong electrostatic attraction in a face-centered cubic crystal lattice. This crystal structure is so iconic that it is often simply called the rock salt structure and is studied extensively in chemistry courses. In nature, sodium chloride is found dissolved in ocean water (about 3.5% by mass) and in massive underground deposits called halite. It is harvested through solar evaporation of seawater or by mining salt domes. Humans have used salt for thousands of years for food preservation, seasoning, and as a form of currency — the word salary derives from the Latin salarium, which is connected to salt. Sodium chloride plays a vital role in human physiology. Na⁺ and Cl⁻ ions are essential electrolytes that help regulate fluid balance, nerve impulse transmission, and muscle contraction. Industrially, NaCl is the starting material for the chlor-alkali process, which produces chlorine gas (Cl2) and sodium hydroxide (NaOH) through electrolysis of brine — two of the most important industrial chemicals. It is also used in water softening, de-icing roads, and food processing. When dissolved in water, sodium chloride dissociates completely into its ions, making it a strong electrolyte. This property is central to lessons on electrolyte solutions, conductivity, and colligative properties such as boiling point elevation and freezing point depression. The formation of NaCl from its elements is a textbook example of an exothermic reaction and ionic bonding. For chemistry students, sodium chloride connects concepts of electron transfer, lattice energy, solubility, and stoichiometry in a single, tangible compound they encounter every day at the dinner table.

IUPAC Name

sodium chloride

CAS Number

7647-14-5

PubChem CID

5234

Molecular Formula

NaCl

Molar Mass

58.44 g/mol

State at STP

solid

Appearance

White crystalline solid

Physical Properties

Melting Point

801 °C

Boiling Point

1413 °C

Density

2.165 g/cm³

Solubility in Water

360 g/L at 25 °C

Specific Heat

0.864 J/(g·K)

ΔH°f

-411.12 kJ/mol

ΔG°f

-384.04 kJ/mol

S°

72.11 J/(mol·K)

Composition

Bonding

Reactions