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). No substance-specific occupational exposure limit exists; only the generic nuisance-dust limits apply. 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. We deliberately do not publish occupational exposure limits or other regulatory thresholds: those values are revised over time and differ between jurisdictions, so the only correct source is the current SDS and the regulations that apply where you work.