Question

how can you create a calcium hydroxide or limewater using calcium carbonate?
http://en.wikipedia.org/wiki/Limewater

Answer 1

The task is to convert calcium carbonate to calcium hydroxide. It must be some kind of reaction where one of the reactants is $\mathrm{CaCO_3}$ and one of the products is $\mathrm{Ca(OH)_2}$.

I know two ways how to do it. The first one is next conversation:

$$\mathrm{Ba(OH)_2} + \mathrm{CaCO_3} \rightarrow \mathrm{BaCO_3} + \mathrm{Ca(OH)_2}$$

$\mathrm{BaCO_3}$ is more not soluble than $\mathrm{CaCO_3}$ than that's why it is possible to get $\mathrm{Ca(OH)_2}$

Second way is to decompose $\mathrm{CaCO_3}$ by heating and then dissolve solid product (CaO) in water:

$$\mathrm{CaCO_3} \rightarrow \mathrm{CaO} + \mathrm{CO_2\uparrow}$$ $$\mathrm{CaO} + \mathrm{H_2O} \rightarrow \mathrm{Ca(OH)_2}$$