The given chemical reactions are as follows:

1. CaCO3 (Calcium carbonate) -> CO2 (Carbon dioxide) + CaO (Calcium oxide)
This reaction occurs when calcium carbonate is heated, resulting in the formation of carbon dioxide gas and calcium oxide.

2. CO2 (Carbon dioxide) -> CO (Carbon monoxide)
This reaction occurs when carbon dioxide is reduced, resulting in the formation of carbon monoxide gas.

3. CO (Carbon monoxide) + 1/2 O2 (Oxygen) -> CO2 (Carbon dioxide)
This reaction occurs when carbon monoxide reacts with oxygen, resulting in the formation of carbon dioxide gas.

4. CO2 (Carbon dioxide) + H2O (Water) -> H2CO3 (Carbonic acid)
This reaction occurs when carbon dioxide dissolves in water, resulting in the formation of carbonic acid.

5. H2CO3 (Carbonic acid) -> NaHCO3 (Sodium bicarbonate)
This reaction occurs when carbonic acid reacts with sodium hydroxide, resulting in the formation of sodium bicarbonate.

6. NaHCO3 (Sodium bicarbonate) -> Na2CO3 (Sodium carbonate) + CO2 (Carbon dioxide) + H2O (Water)
This reaction occurs when sodium bicarbonate is heated, resulting in the formation of sodium carbonate, carbon dioxide gas, and water.

7. Na2CO3 (Sodium carbonate) + BaCl2 (Barium chloride) -> BaCO3 (Barium carbonate) + 2 NaCl (Sodium chloride)
This reaction occurs when sodium carbonate reacts with barium chloride, resulting in the formation of barium carbonate and sodium chloride.