This is an acid-base reaction (neutralization): K2O is a base, CO2 is an acid.
Reactants:
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K2O – Potassium oxide, Potassium oxidopotassium
Other names: Potash, Dipotassium oxide, Dipotassium monoxide
Appearance: Pale yellow solid ; Grey hygroscopic crystalline powder
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.]
Products:
K2CO3 – Potassium carbonate
Other names: Carbonate of potash, Dipotassium carbonate, Sub-carbonate of potash
Appearance: White, hygroscopic solid ; Colourless hygroscopic crystals or hygroscopic white powder