Why is it important to record the temperature at which the #"KC"l"O"_3# recrystallises rather than the temperature at which it all dissolves?

1 Answer
Jun 9, 2018

Could you give us the background on your question...?


Usually, when we recrystallize a solute, we take the solute, add some solvent (which here is water), and give it a good blast with a heat-gun...

Because we want to get ALL the solute up into solution, we heat the solvent up to near boiling routinely...we do the same thing with organic solvents such as ethanol or heptane... IDEALLY we want to use the MINIMUM solvent to get that solute up into solution, and so we heat the solvent up to its boiling point (of course we take care that our supervizor does not see us heating a flammable solvent with a naked flame!). The only solvent we would use with an ionic salt, and one that is potentially oxidizing, is WATER.

Of course, then we take the filtered solution and then put it into a fridge (i.e. if the solvent is water), and NOT into a freezer (why not?). With organic solvents we COULD put the solution into a sparkless freezer...