Question

what is the need to heat solution

Answer 1

If the temperature is too low (below 55 degrees celsius), the interaction between the oxalate and the potassium permangante will move too slow as to be used as a practical lab experiment.Above 60 degrees celsius, oxalate acid begins to decompose, so its important to stay in this range. 

maybe it helps

Answer 2

the heat evolved or absorbed when a substance dissolves; specifically : the amount involved when one mole or sometimes one gram dissolves in a large excess of solvent.so we need heat solution