Sodium Bromide
Properties
| State | Solid at room temperature |
| Color | White crystalline powder |
| Solubility | Very soluble in water (94.3 g/100 mL at 25 °C) |
| Melting Point | 747 °C |
| Boiling Point | 1390 °C |
About Sodium Bromide
Sodium bromide is the bromide analog of table salt — same face-centered cubic rock-salt lattice, similar physical handling, but a softer ion that does very different chemistry. Molar mass 102.894 g/mol, dense crystal (3.21 g/cm³), and a saturated brine that hits 1.5 g/mL near room temperature. That density is the reason NaBr brines own the oilfield completion-fluid market: when you finish drilling a well and need a clear, particulate-free fluid that sits in the wellbore at 11-14 lb/gal to balance reservoir pressure, NaBr (or CaBr2 for higher densities) is what goes in. Historically NaBr was the active in 19th-century sedative tonics — the original 'bromides' that doctors prescribed for nervous complaints and epilepsy from about 1857 until phenobarbital displaced them in 1912. The mechanism is partial chloride substitution in neuronal Cl- channels, and the side effect of long-term use was bromism: skin rash, anorexia, slurred speech, and the sedation that gave the word 'bromide' its second meaning of a tedious or commonplace remark. In modern veterinary medicine, potassium bromide (occasionally sodium bromide) is still a first-line anticonvulsant for refractory canine epilepsy.
Where you'll encounter it
If you've ever swum in a bromine-treated hotel hot tub, you've waded through the downstream chemistry of NaBr — the salt is added to the water along with an oxidizer like sodium dichloroisocyanurate, which converts bromide to hypobromous acid HOBr, a sanitizer that's gentler on swimmer eyes than chlorine and more stable in the 38–40 °C water. In a black-and-white film darkroom, NaBr is the antifoggant in developer baths: a small amount of bromide ion suppresses chemical fog by reducing the rate of silver halide reduction in unexposed grains. Oilfield service crews see 11.7 lb/gal NaBr completion brine in 5-gallon jugs labeled with HSE warnings about chloride/bromide stress corrosion on austenitic stainless steel tubing. Veterinarians prescribe potassium bromide capsules to elderly Labradors with epilepsy refractory to phenobarbital, with the same bromism warnings their human predecessors faced a century earlier.
Common Uses
- Clear high-density completion fluid in oil and gas well finishing
- Bromide source for hot-tub and spa sanitization with oxidizer activation
- Antifoggant in silver halide photographic developer formulations
- Anticonvulsant in canine and feline refractory epilepsy treatment
- Bromide ion source for organobromine synthesis via Finkelstein reaction
- Hydrogen-bromide generation in situ from NaBr plus sulfuric acid
- Industrial wood preservation as a fire-retardant component
- Mercury collection from natural-gas processing as HgBr2 precipitate
Safety Information
Low acute toxicity. GHS: H319 (eye irritation), H335 (respiratory irritation from dust). OSHA has not set a specific PEL; the OSHA particulates-not-otherwise-regulated limit (15 mg/m³ total dust, 5 mg/m³ respirable) applies. The chronic concern is bromism — accumulation over weeks of exposure produces the classic rash, anorexia, ataxia, and obtundation seen historically in patients taking bromide sedatives. Plasma bromide above 12 mEq/L is symptomatic. Bromide also displaces chloride in laboratory chloride assays, giving spuriously high results. NaBr brines under stress can cause chloride-bromide stress corrosion cracking in 304/316 stainless steel above 50 °C. Standard chemical PPE is adequate.
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.