# Question #18b0f

Mar 16, 2017

Well is $\text{calcium oxide}$ known............?

#### Explanation:

$\text{Calcium oxide}$ or quicklime is certainly known. Formally it contains $C {a}^{2 +}$ and ${O}^{2 -}$ ions. The high melting and boiling points observed for this compound are certainly consistent with an ionic species.

In aqueous solution $C a O$ reacts to give an aqueous solution of so-called $\text{slaked lime}$:

$C a O \left(s\right) + {H}_{2} O \left(l\right) \rightarrow C a {\left(O H\right)}_{2} \left(a q\right) + \Delta$

This reaction is the basis for the cement and mortar industry, mix in aggregate, i.e. crushed stone, and you get concrete, the premier building material of modernity.