When sodium hydroxide (NaOH) is added to iron(II) sulfate (FeSO₄), a green precipitate forms. Here's the breakdown:

* Reaction: The reaction produces iron(II) hydroxide (Fe(OH)₂) and sodium sulfate (Na₂SO₄).

FeSO₄(aq) + 2NaOH(aq) → Fe(OH)₂(s) + Na₂SO₄(aq)

* Color Change: The iron(II) hydroxide precipitate is greenish-white, but it quickly oxidizes in air, turning a dirty green color.

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