Here's the balanced chemical equation for the reaction of slaked lime (calcium hydroxide) with carbon dioxide:

Ca(OH)₂ (s) + CO₂ (g) → CaCO₃ (s) + H₂O (l)

Explanation:

* Ca(OH)₂ represents slaked lime (calcium hydroxide), which is a solid (s).

* CO₂ represents carbon dioxide, which is a gas (g).

* CaCO₃ represents calcium carbonate, a solid (s), which forms the hardened part of the mortar.

* H₂O represents water, which is a liquid (l).

This reaction is an example of a neutralization reaction where a base (calcium hydroxide) reacts with an acid (carbon dioxide) to form a salt (calcium carbonate) and water.