- Sodium chloride (NaCl) is table salt – a compound of sodium and chlorine with a molar mass of 58.44 g/mol; it melts at 801°C.
- Table salt contains at least 97% NaCl and is often iodised and contains an anti-caking agent.
- Saline solution is not pure sodium chloride but a 0.9% solution of it in water.
- The WHO recommends no more than 5 g of salt a day (about 2 g of sodium) – 1 g of salt contains about 0.4 g of sodium.
- Sodium chloride is a raw material for the chemical, food and cosmetics industries and for road maintenance.
In short: sodium chloride is a chemical compound with the formula NaCl – the salt of hydrochloric acid and sodium, better known as table salt. Its molar mass is 58.44 g/mol, it consists of about 39% sodium and 61% chlorine, melts at 801°C and dissolves readily in water, giving a neutral solution. In nature it occurs as the mineral halite (rock salt) and in seawater.
Sodium chloride is essential for life: it supplies sodium (Na⁺) and chloride (Cl⁻) ions, which regulate water balance, blood pressure and nerve impulse transmission. We use it to season and preserve food, and industry uses it as a chemical raw material, an ingredient of medicines and cosmetics and a de-icing agent. Below you will find the most important properties of sodium chloride and its uses.
What is sodium chloride?
Sodium chloride is an inorganic chemical compound from the chloride group – a salt of hydrochloric acid and sodium. It has the chemical formula NaCl. It is the primary ingredient in table salt, brewed salt and road salt. It occurs naturally in nature as a mineral forming rock salt deposits called halites. Sodium chloride provides the body with the ions necessary for its functioning, has a hydrating effect, maintaining the electrolytic balance of body fluids, proper blood pressure and the proper functioning of the nervous system.
Physical and chemical properties of sodium chloride
Sodium chloride consists of colourless or white crystals with a salty taste and no odour. It has an ionic structure: Na⁺ and Cl⁻ ions form a cubic crystal lattice (each ion is surrounded by six ions of the opposite charge), which is why salt crystals are cube-shaped. Pure NaCl is only slightly hygroscopic – it absorbs moisture only above about 75% relative humidity; caking of kitchen salt is mainly caused by impurities of other salts.
Key physical and chemical data:
| Parameter | Value |
|---|---|
| Chemical formula | NaCl |
| Molar mass | 58.44 g/mol |
| Elemental composition | approx. 39.3% sodium, 60.7% chlorine |
| CAS number | 7647-14-5 |
| Density | 2.16 g/cm³ |
| Melting point | 801°C |
| Boiling point | 1465°C |
| Solubility in water | approx. 359 g/l (25°C), only slightly temperature-dependent |
| Solubility in ethanol | very low |
| pH of aqueous solution | approx. 7 (neutral) |
| Bonding and structure | ionic, cubic crystal lattice |
Molten or dissolved sodium chloride conducts electricity because it contains free ions. This property is the basis of brine electrolysis, which produces chlorine, hydrogen and sodium hydroxide. Stored correctly in dry, tightly closed packaging, sodium chloride does not lose its properties, which is why salt has no expiry date. Foodcom offers food-grade salt and vacuum salt without anti-caking agent.
Occurrence of rock salt
Sodium chloride naturally occurs in dissolved form in sea water and mineral waters, and as halite, a mineral that forms rock salt deposits. Rock salt can contain admixtures of sand, other chlorides or sulfates, as well as sulfur. Halite was formed by crystallization of sea water or salt lakes. It occurs naturally in arid climates. Rock salt is obtained mainly in Europe (Germany, France, the Netherlands, Poland), North America (USA, Canada, Mexico) and Asia (China, India). In Poland, rock salt deposits are found, among others, in Kujawy (Inowrocław, Ciechocinek), in Kłodawa located in Greater Poland, in Sieroszowice in Lower Silesia, in Wieliczka or Bochnia. Rock salt crystals can be gray, orange, blue or green in color. More than 4 million tons of rock salt are mined annually in Poland, and about 250 million tons worldwide.
Table salt market
Food-grade salt is produced in three ways: by mining and purifying rock salt, by evaporating brine in salt works (vacuum salt) and by evaporating seawater in salt pans (sea salt). Raw rock salt usually contains 90–99% sodium chloride plus impurities such as gypsum, other chlorides and clay minerals, which are removed during purification.
Finished food-grade salt must contain at least 97% sodium chloride on a dry basis. The world’s largest salt producers are China, the United States and India; in Poland salt is mined in Kłodawa, Inowrocław and Sieroszowice, among other places. Only part of global production goes into food – most salt is used by the chemical industry and for road maintenance.
Is sodium chloride the same as table salt? Composition and types of salt
Yes – table salt is mostly sodium chloride, but it is not pure NaCl. In addition to at least 97% sodium chloride, it may contain:
- iodine – in many countries, including Poland, household table salt is iodised (with potassium iodide or iodate, about 30 mg of iodine per kilogram) to prevent iodine deficiency,
- anti-caking agents – e.g. potassium ferrocyanide (E536), which prevents the salt from clumping,
- natural impurities – traces of calcium, magnesium, potassium or sulphates, especially in unrefined salt.
The most common types of salt differ in origin and degree of purification, but all consist mainly of NaCl:
| Type of salt | Origin | Characteristics |
|---|---|---|
| rock salt | halite deposits | coarse, sometimes with mineral impurities |
| vacuum salt | evaporated brine | fine, very pure (over 99% NaCl) |
| sea salt | evaporated seawater | traces of magnesium and calcium |
| Himalayan salt | deposits in Pakistan | pink colour from iron compounds, mostly NaCl |
| low-sodium salt | NaCl blended with potassium chloride | less sodium, slightly bitter aftertaste |
Read more about potassium salt, used to reduce sodium in food, in the article Potassium chloride in industry.
Uses of sodium chloride
Sodium chloride is used as a food additive, imparting a salty taste to processed foods. It also acts as a preservative. It is also used in medicine, cosmetics production, road construction, chemical, glass and tanning industries. Detailed properties and uses of salt are listed below.
Uses in medicine
Sodium chloride is one of the basic compounds in medicine. Its most important use is as saline solution, a 0.9% solution of NaCl in water (9 g of salt per litre). It is isotonic with blood plasma, so it is given intravenously in dehydration and electrolyte loss and is used to dissolve medicines, clean wounds, rinse eyes and nose and for inhalation. The first attempts to treat dehydration with a salt solution were made as early as 1831–1832, during a cholera epidemic.
Is sodium chloride the same as saline? No – saline is a sterile solution of sodium chloride at a precisely defined concentration. Hypertonic (e.g. 3%) solutions are also used in medicine, for example for nebulisation, as well as hypotonic ones. Homemade solutions of table salt should not be used in the eyes or for inhalation instead of sterile pharmacy products.
Use in cosmetics
Sodium chloride is also valued by cosmetic manufacturers. In finished products, the compound has various functions. Among other things, it is used as a filler, increasing the volume of the product, and as a fragrance or to suppress other undesirable odors. It also causes an increase in product viscosity and helps stabilize emulsions. It is often used in shampoos or toothpastes, as well as in the manufacture of soaps and detergents.
Use in food production
Sodium chloride is widely used in the food industry. Salt is found in highly processed foods, in processed meats, as well as in butter, cheese and other dairy products, and in bread. Its role is mainly to enhance the flavor of products, but it also acts as a preservative, a binding agent, e.g. in sausages, an additive to control fermentation, e.g. in the production of cheese or bread dough, an enhancer of flavor, texture and product color, e.g. to color processed meat products. The preservative effect of salt, which has been known for many years, is to inhibit the growth of bacteria – microorganisms are unable to live in a salty environment, in addition, salt acts as a cheap and safe desiccant, which, thanks to its hygroscopicity, draws water out of bacterial cells. Therefore, the addition of salt extends the shelf life of products such as meat, fish and cabbage.
Industrial applications
Sodium chloride has a wide range of industrial applications:
- It is used in the chemical industry as a raw material for obtaining other compounds: hydrochloric acid, sodium hydroxide, sodium carbonate, sodium, chlorine, calcium chloride, sodium sulfate.
- Sodium chloride crystals are used in the construction of measuring apparatus, such as infrared absorption spectrophotometers, and are also used in optical components, such as prisms, operating in the infrared spectral range. This is because sodium chloride crystals have an optical transmittance of about 90% for infrared light.
- Sodium chloride is also encountered in the road industry as an agent for melting ice and snow, since a solution of water and sodium chloride freezes at very low temperatures (it is effective to use salt down to -10°C).
- Sodium chloride is also used in the glass industry – the sodium carbonate obtained from it is used to make glass, as well as dyes and other chemicals.
- The compound is also used in refrigeration, as it forms a cooling solution below -20°C when combined with ice.
- In oil and gas extraction, salt is used as an important ingredient in drilling fluids.
- In the construction industry, salt accelerates the hardening of concrete, and is also used to protect soil and provide stability for road foundations.
- In textiles and dyeing, salt rinse is used to separate organic impurities and dry out dye deposits.
- In the tanning industry, salt is used in the treatment of animal hides to inhibit microbial activity and prevent the leather from becoming too dry.
- Sodium chloride is also used in the production of rubber (buna, neoprene, white rubber) and ion-exchange resins for softening water.
- In the pulp and paper industry, it is used to extract chlorine dioxide, which is used to bleach wood pulp in paper production.
- In firefighting, sodium chloride is used as the main extinguishing agent in some fire extinguishers (Class D extinguishers used to extinguish flammable metal fires).
The use of salt in everyday life
At home, salt is used mainly to season and preserve food – for pickling, curing meat, salting fish or making brine. A salt and water solution is sometimes used as a gargle, and coarse salt for cleaning pans, pots and chopping boards.
Moderation matters: the World Health Organization recommends that adults consume no more than 5 g of salt a day, about one level teaspoon. This is not a requirement but an upper limit – most salt in the diet comes from bread, cold cuts, cheese and processed food, not from the salt shaker.
In winter, magnesium chloride is increasingly used instead of road salt, as it melts ice effectively down to about −15°C. A comparison of both salts can be found in the article Magnesium chloride – what is it and what is it used for?
Is sodium chloride harmful?
Sodium chloride is essential for life, and safety data sheets do not classify it as hazardous. Only an excess in the diet is harmful: eating too much salt promotes high blood pressure and, as a result, heart disease, stroke and kidney disease.
- How much is 5 g of salt? About one level teaspoon. It contains about 2 g of sodium – the amount the WHO says should not be exceeded in a day.
- How do you convert sodium to salt? Multiply the sodium on the label by 2.5 – 1 g of sodium is about 2.5 g of salt, and 1 g of salt contains about 0.4 g of sodium.
- Technical and road-grade sodium chloride is not fit for consumption – it may contain impurities and additives that are not permitted in food.
Too little sodium can also be dangerous (e.g. with heavy sweating or vomiting), but with a typical diet the problem is usually too much of it. For food, always choose salt labelled as food grade, and in industry, sodium chloride with a specification suited to the process.
