Sodium bicarbonate and sulfuric acid are, respectively, the acid-salt of a strong base and a strong acid. The interaction between the two substances is categorically termed a “neutralization reaction.” Theoretically, combining two molecules of sodium bicarbonate and one molecule of sulfuric acid will produce one molecule of sodium sulfate and two molecules of carbonic acid. Actually, however, the carbonic acid in that environment is unstable, and so does not remain in solution, but quickly dissociates into water and carbon dioxide gas, the latter escaping into the atmosphere. Overall, the reaction is written 2 NaHCO3 + H2SO4 → Na2SO4 + 2 H2O + 2 CO2↑.
Sulfuric acid is among the strongest of the inorganic or “mineral” acids. Unlike many other strong acids, such as nitric (HNO3) and hydrochloric (HCl) acids, sulfuric acid contains within its structure two hydrogen atoms. In solution, these take the form of hydrogen ions. When both hydrogen ions are replaced or neutralized, the resulting product is a full salt, as for example, potassium sulfate (K2SO4). If, on the other hand, only one hydrogen ion is replaced, the product is a half-salt, occasionally called an acid-salt — in this instance potassium hydrogen sulfate (KHSO4), perhaps better known as potassium bisulfate.
It will now be clear that sodium bicarbonate is just such an acid-salt or half-salt, and results from the neutralization of only one available hydrogen ion found in its parent, carbonic acid (H2CO3). This acid undergoes the partial neutralization reaction NaOH + H2CO3 → NaHCO3 + H2O, rather than 2 NaOH + H2CO3 → Na2CO3 + 2 H2O, the latter representing complete neutralization. The connection between sodium bicarbonate and sulfuric acid is thus one of partial neutralization of an acid-salt of a strong base by a strong acid. Another possibility is the partial neutralization, not of sulfuric acid, but of the sodium bicarbonate, to produce sodium bisulfate via the reaction equation NaHCO3 + H2SO4 → NaHSO4 + H2O + CO2↑.
The two compounds, sodium bicarbonate and sulfuric acid, are industrially of major importance. Sulfuric acid is used commercially in the manufacture of fertilizers, in steel, in lead-acid batteries and for petroleum refining. Sodium bicarbonate is generally safe to handle, and is useful in dealing with acid spills, especially sulfuric acid spills. It is also of importance in food preparation, in the handling of certain small fires, and in hygiene and medicine. The full neutralization product between sodium bicarbonate and sulfuric acid, sodium sulfate, is an abundant byproduct of certain other industrial processes.