Sodium Chloride
Properties
| State | Solid (white crystalline) |
| Color | White |
| Solubility | Soluble in water (360 g/L at 25 °C) |
| Melting Point | 801 °C |
| Boiling Point | 1413 °C |
About Sodium Chloride
Sodium chloride is the textbook ionic crystal — face-centered cubic Fm-3m lattice with Na+ and Cl- alternating in a 6-coordinate arrangement, lattice energy of 787 kJ/mol, and a unit cell that gets photographed in every introductory solid-state chemistry course. Molar mass 58.44 g/mol, melts at 801 °C, dissolves to 360 g/L at 25 °C with a slight endotherm that makes the solution feel cool to the touch. Beyond the kitchen, NaCl is the input feedstock for the chlor-alkali industry: electrolyze a saturated brine in a membrane cell and you get chlorine gas at the anode, hydrogen at the cathode, and 30 percent NaOH solution accumulating around the cathode. That single process makes most of the world's caustic soda, almost all of the elemental chlorine for PVC manufacturing, and the hydrogen byproduct that increasingly feeds fuel-cell and fine-chemical demand. Global salt production is about 290 million tonnes a year. About 60 percent feeds the chemical industry (chlor-alkali plus soda ash via the Solvay process), 20 percent goes to road de-icing, and only about 6 percent is the food-grade salt that reaches kitchen tables. Halite mining in places like Wieliczka in Poland and Cheshire in England has been continuous for centuries — those mines are now also tourist attractions.
Where you'll encounter it
If you've ever waited in line at a salt-truck filling station after a snowstorm, watched a chemistry student cleave a NaCl crystal along its (100) face with a razor blade, or run a 0.9 percent saline IV drip into a dehydrated patient at the ER, you've used three completely different applications of the same compound. In the molecular biology lab, NaCl is the standard ionic strength adjuster for everything from agarose gel buffers (TAE, TBE) to protein precipitation (salting out with ammonium sulfate is the cousin technique). Cell biologists buffer their media to 137 mM NaCl plus 2.7 mM KCl in PBS specifically because that's what blood plasma runs at. Ice cream makers ring a churn with rock salt and ice precisely because dissolving NaCl into the melting ice depresses the freezing point to about –21 °C at the eutectic, which is cold enough to freeze butterfat-water mixture into solid scoops. Cured ham, sauerkraut, and lacto-fermented kimchi all rely on selective osmotic killing of non-halophilic spoilage organisms by 2-5 percent salt brines while letting Lactobacillus do the fermentation work.
Common Uses
- Membrane-cell electrolysis feedstock for Cl2, NaOH, and H2 in chlor-alkali
- Solvay-process input for sodium carbonate manufacture
- Highway de-icing rock salt for surface temperatures down to –10 °C
- 0.9 percent normal saline for IV fluid resuscitation and wound irrigation
- Ionic strength adjuster in PCR, electrophoresis, and protein purification
- Brine cure for ham, bacon, lox, sauerkraut, and lacto-fermented vegetables
- Freezing-point depressant in ice cream churns and cold-bath laboratory work
- Regenerant brine for sodium-form ion-exchange water softener resin
Safety Information
GRAS for food use (FDA 21 CFR 184.1639); WHO recommends adult intake under 5 g/day. GHS: not classified — no H-codes assigned. OSHA has not set a PEL. The risks are dietary not acute: chronic intake above 5 g/day correlates strongly with hypertension, increased stroke risk, and increased gastric cancer incidence. Acute oral lethal dose in adults is roughly 0.5–1 g/kg body weight (about 35–70 g for a 70 kg person), with several documented pediatric deaths from forced salt ingestion or naturopathic protocols. Hypernatremic encephalopathy from rapid IV correction of hyponatremia (osmotic demyelination syndrome) is a real iatrogenic risk that drives slow saline correction protocols. Saturated brines are mildly corrosive to carbon steel; chloride stress corrosion cracks austenitic stainless above 60 °C. Standard kitchen and lab handling is fine.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.