You haven't been too clear about whether you are actually cooling the reaction, externally, while adding the PE. My guess is you are not.
And my second guess is that your guess about what Fulmen is saying is correct. I also think this is one of your problems. You can't expect a reaction
to stay below a certain temperature just by cooling the reactants while the reaction is exothermic.
Also have a look at the amount of energy it takes to get water from, example given, -18 to 0 degrees and the amount of energy it takes to get water
from -9 (frozen, ice-bath) to +9. |