This is a precipitation reaction: Mg(OH)2 is the formed precipitate.
Reactants:
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Mg(NO3)2 – Magnesium nitrate
Other names: Nitromagnesite (hexahydrate), Nitric acid, magnesium salt
Appearance: White crystalline solid ; Hygroscopic colourless or white crystals
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:
Mg(OH)2 – Magnesium hydroxide
Other names: Magnesium dihydroxide, Milk of magnesia, Magnesia, [Milk of]
Appearance: White solid
NaNO3 – Sodium nitrate
Other names: Peru saltpeter, Soda niter, Cubic niter
Appearance: White powder or colorless crystals ; Colourless hygroscopic crystals
2 + 2 NaOH → Mg(OH)2 + 2 NaNO3 – Balanced equation){kind=link}