Final answer:
In the reaction given, H2O and CO3 2- act as Brønsted-Lowry acids by donating protons to form OH- and HCO3-, respectively.
Step-by-step explanation:
The Brønsted-Lowry theory defines an acid as a substance that donates hydrogen ions (protons) and a base as a substance that accepts them. Looking at the reaction H2O + CO32- → HCO3- + OH-, we can identify the Brønsted-Lowry acids by determining which substances donate a proton.
Water (H2O) donates a proton to the carbonate ion (CO32-), forming hydroxide (OH-) and bicarbonate (HCO3-). Therefore, H2O and CO32- are acting as Brønsted-Lowry acids because they donate a proton to form OH- and HCO3- respectively. In summary, the Brønsted-Lowry acids in this reaction are H2O and CO32-.