[Fridushka]

We had an organic unknown cpd..we dissolve in cold water it didn't work then in hot it dissolve and start to crystallize.
Well as i know when the unknown is dissolved in water then we can conclude that the hydrocarbon consist less than 4 carbon or has some functional group, i.e. it can be alcohol aldehyde and some other. And also we know that if something was soluble in water in can be soluble in basic and acidic medium, so after knowing that it is soluble we don't do those test because it would be meaningless..
So what is my question that is there any difference between cold and hot for this identification information.. I'm a bit confused!

Thanks for your time

[Smrt guy]

I wouldn't say that it's pointless to test the effect of pH on solubility if it does not dissolve in water at RT.  Increased solubility at high temps only means that it has to have some kind of polar group (pure hydrocarbons should be insoluble even at high temps).