This is an acid-base reaction (neutralization): CO2 is an acid, Na2O is a base.
Reactants:
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CO2
Names: Carbon dioxide, {{plainlist|, CO2
Appearance: Colorless gas ; Odourless colourless compressed liquefied gas ; Colorless, odorless gas. [Note: Shipped as a liquefied compressed gas. Solid form is utilized as dry ice.]
Na2O – Sodium oxide
Other names: Disodium oxide, Sodium monoxide, Disodium monoxide
Appearance: White solid ; White lumps or powder
Products:
Na2CO3 – Sodium carbonate
Other names: Soda ash, Washing soda, Soda crystals
Appearance: White solid, hygroscopic ; White hygroscopic powder