This is an acid-base reaction (neutralization): Zn(OH)2 is an acid, NaOH is a base.
Reactants:
[external_link offset=2]
Zn(OH)2
Names: Zinc hydroxide, Zinc(II) hydroxide
Appearance: White powder
NaOH
Names: Sodium hydroxide, Caustic soda, Lye
Appearance: White, waxy, opaque crystals ; White hygroscopic solid in various forms ; Colorless to white, odorless solid (flakes, beads, granular form).
Products:
Na2ZnO2
Names: Sodium zinc oxide
H2O – Water, oxidane
Other names: Water (H2O), Hydrogen hydroxide (HH or HOH), Hydrogen oxide
Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas