How can potassium hydroxide be prepared from available potassium chloride (KCl) and Quick Lime (CaO)
Mixing $\ce{KCl + CaO}$, or $\ce{KCl + Ca(OH)2}$, will never produce pure $\ce{KOH}$ without $\ce{Ca(OH)2}$. And this Ca(OH)2 will prevent soap from being synthesized out of oil, as $\ce{(Ca(OH)2}$s destroy soap in case a little bit of soap has been synthesized. The only way of producing $\ce{KOH}$ out of $\ce{CaO}$ or $\ce{Ca(OH)2}$ is to mix it with potassium carbonate $\ce{K2CO3}$. Of course $\ce{Ca(OH)2}$ is not very soluble in water. But $\ce{CaCO3}$ is still more insoluble. So the following reaction is possible :$$\ce{Ca(OH)2 + K2CO3 -&gt; 2 KOH + CaCO3(s)}$$ And the insoluble $\ce{CaCO3}$ can be filtrated to produce a KOH solution