This is an acid-base reaction (neutralization): CO2 is an acid, ZnO is a base.
Reactants:
CO2
Names: Carbon dioxide, {{plainlist|, CO2Carbonic acid gas, Dry ice, [CO2], Carbonic anhydride, R-744, E-290, E 290, E290, Carbonic acid anhydride, Carbon-12 dioxide, Methanedione, Carbon oxide, CO₂, [Note: Normal constituent of air (about 300 ppm)].
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.]
ZnO
Names: Zinc oxide, Zinc white, CalaminePhilosopher's wool, Chinese white, Flowers of zinc, Zinc (as oxide), Zinc paste, Zincum oxydatum, Zinkoxid, Oxyde de zinc, Zinc (as zinc oxide), Zinci oxydum, Óxido de cinc, Zinc(II) oxide, Zinc monoxide, C.I. Pigment White 4, Zinc peroxide
Appearance: White solid ; White powder ; White, odorless solid.