Bromine reaction. Bromine gas (orange) forming as the product of a reaction between sulphuric acid (in bottle) and sodium bromide (in test tube). The concentrated sulphuric acid is a strong oxidizing agent. The initial reaction of sodium bromide (NaBr) forms hydrogen bromide gas (HBr), but this is oxidized by the sulphuric acid (H2SO4) to form bromine gas (Br2). The other products are sulphur dioxide gas (SO2), water (H2O) and sodium hydrogen sulphate (a solid, NaHSO4). The equations for the two reactions are: (1) NaBr + H2SO4 --> HBr + NaHSO4 and (2) 2 HBr + H2SO4 --> Br2 + SO2 + 2 H2O