When copper(II) nitrate (Cu(NO₃)₂) reacts with sodium hydroxide (NaOH), it results in a precipitation reaction where a solid compound, copper(II) hydroxide (Cu(OH)₂) precipitates out of the solution. The reaction also produces sodium nitrate (NaNO₃), which remains dissolved in the solution.

Here's the balanced chemical equation:

Cu(NO₃)₂ (aq) + 2NaOH (aq) → Cu(OH)₂ (s) + 2NaNO₃ (aq)

Here's what happens:

* Copper(II) nitrate (Cu(NO₃)₂) and sodium hydroxide (NaOH) are both dissolved in water (aq).

* When the solutions mix, the copper(II) ions (Cu²⁺) from the copper(II) nitrate react with the hydroxide ions (OH⁻) from the sodium hydroxide.

* Copper(II) hydroxide (Cu(OH)₂) is insoluble in water, so it forms a solid precipitate (s).

* Sodium nitrate (NaNO₃) remains dissolved in the solution (aq).

You'll observe a blue precipitate forming in the solution, which is the characteristic color of copper(II) hydroxide.