The gases evolved from the reaction between sodium carbonate (Na2CO3) and hydrochloric acid (HCl) are carbon dioxide (CO2) and hydrogen chloride (HCl). The reaction can be represented as follows:

Na2CO3 (aq) + 2HCl (aq) → 2NaCl (aq) + H2O (l) + CO2 (g)

In this reaction, the carbonate ions (CO3^2-) in sodium carbonate react with hydrogen ions (H+) from hydrochloric acid to form water (H2O) and carbon dioxide (CO2) gas. Sodium chloride (NaCl) is also formed as a byproduct of the reaction. The carbon dioxide gas produced in this reaction can be observed as bubbles forming in the solution.