This is an acid-base reaction (neutralization): NaOH is a base, HBr is an acid.
Reactants:
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NaOH
Names: Sodium hydroxide, Caustic soda, Lye
Appearance: White, waxy, opaque crystals ; White hygroscopic solid in various forms ; Colorless to white, odorless solid (flakes, beads, granular form).
HBr – Hydrogen bromide, Bromane
Other names: Hydrobromic acid, Hydronium bromide, HBr
Appearance: Colorless gas ; Colorless/faint yellow liquid ; Colourless compressed liquefied gas with pungent odour ; Colorless gas with a sharp, irritating odor. [Note: Shipped as a liquefied compressed gas. Often used in an aqueous solution.]
Products:
H2O – Water, oxidane
Other names: Water (H2O), Hydrogen hydroxide (HH or HOH), Hydrogen oxide
Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas
NaBr – Sodium bromide
Other names: Bromide salt of sodium, Trisodium tribromide, NaBr