I was reading that ethanol can only be purified up to something like 95% by distillation and further purification calls for CaO. Why is this? Is CaO a drying agent? Why is it that you can't seperate water completely from ethanol? Is it just not feasible without CaO, like the tiny amount of water is nearly impossible to remove due to their being so much ethanol around it. Their structures are similar, they both are polar with the OH group and there are few carbons on the ethanol so they are pretty miscible (sp?). So I guess I can see how water would have trouble breaking free of its bond to ethanol in solution, at such a low concentration. I can see it, but is it right?