How to verify that ethanol is infinitely soluble in water? My textbook [Chemistry Live, Declan Kennedy] states that ''Ethanol is said to be infinitely soluble in water''. It then says ''verify this for yourself by mixing some ethanol with water in a test tube''.
Both water and ethanol are colourless. How can I observe that they are infinitely soluble ?
The better term is miscible in all ratios. The idea behind the term is that you can have a mixture from 99.9999… % water and 0.0000…1 % ethanol to a mixture of 0.0000…1 % water and 99.9999…% ethanol. No infinity necessary.
The obvious opposite to miscible is immiscible (in some or all ratios). A common pair of household liquids that are immiscible are fatty oils and water. In the chemistry lab, hexane and water might be a better example.
To verify the miscibility of water and ethanol, set up a parallel experiment with water and hexane/a fatty oil such as sunflower oil. You will notice that a fully immiscible pair will never mix, there will always be two different bits of liquid visible. You can try a little oil/hexane and lots of water and vice-versa. On the other hand, a miscible pair will mix and you get a solution where you cannot tell one from the other.
For completeness, partially miscible: if you repeat the experiment with ether and water you will observe that the first couple of drops of water will dissolve in sufficient volumes of ether (and vice-versa) but if more is added you will again get two phases.