The reaction between sodium hydroxide (NaOH) and calcium bicarbonate (Ca(HCO3)2) results in the formation of sodium bicarbonate (NaHCO3), calcium carbonate (CaCO3), and water (H2O). The chemical equation for this reaction is:

2NaOH(aq) + Ca(HCO3)2(aq) → 2NaHCO3(aq) + CaCO3(s) + H2O(l)

In this reaction, sodium hydroxide acts as a base, while calcium bicarbonate acts as an acid. The hydroxide ions (OH-) from sodium hydroxide react with the bicarbonate ions (HCO3-) from calcium bicarbonate to form water molecules and carbonate ions (CO32-). The carbonate ions then react with calcium ions (Ca2+) to form insoluble calcium carbonate, which precipitates out of the solution.

The overall reaction is a neutralization reaction, where an acid and a base react to form a salt (sodium bicarbonate) and water. It's important to note that the reaction may occur in multiple steps, and the formation of intermediate species is possible.