When ammonium hydroxide (NH₄OH) is added to ferrous sulfate (FeSO₄) in water, a green precipitate forms. Here's the breakdown of what happens:

1. Reaction:

Ferrous sulfate (FeSO₄) reacts with ammonium hydroxide (NH₄OH) to produce ferrous hydroxide (Fe(OH)₂) and ammonium sulfate ((NH₄)₂SO₄).

FeSO₄(aq) + 2NH₄OH(aq) → Fe(OH)₂(s) + (NH₄)₂SO₄(aq)

2. Formation of Ferrous Hydroxide:

* The ferrous ions (Fe²⁺) from ferrous sulfate react with the hydroxide ions (OH⁻) from ammonium hydroxide.

* This results in the formation of insoluble ferrous hydroxide (Fe(OH)₂), which precipitates out of solution as a green solid.

3. Ammonium Sulfate:

* The ammonium ions (NH₄⁺) from ammonium hydroxide and the sulfate ions (SO₄²⁻) from ferrous sulfate remain in solution as ammonium sulfate ((NH₄)₂SO₄).

Observations:

* Green precipitate: The most noticeable observation is the formation of a green, gelatinous precipitate of ferrous hydroxide.

* Color change: The solution may also appear slightly cloudy due to the precipitate.

Note: The reaction is reversible, meaning that some ferrous hydroxide can dissolve back into solution if the pH is adjusted or if excess ammonium hydroxide is added.