2006-08-20 10:17:21 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
Depends on the strength of the inter-molecular bonds in the solute. If the bonds are strong, energy is required to break them, and this will come from the thermal energy of the solvent, cooling it. If the bonds are weaker than the hydrogen bonds formed between solute and solvent molecules when the solute dissolves, thermal energy will be given off, heating the solvent.
2006-08-20 10:24:41 · answer #1 · answered by Anonymous · 1⤊ 0⤋
The simple answer is because "that's the way it is." It's actually very rare to find a salt (solute) that aborbs heat and causes the temperature to drop; it's much more common that the temperature rises a little bit.
The physics that cause this arise from the entropy change that occurs upon solvation (dissolving.) Believe it or not, some salts cause more ordering to occur in the solvent than is lost in the salt as it dissolves. These are the substances that "absorb heat" when they dissolve. It's much more common that the total amount of disorder is increased upon dissolution and that releases heat to balance that out. But as to "why" it happens, that isn't really an answer science provides. The physical world is as it is and the goal of science is to develop a model for understanding the world that allows us to predict how things behave. If you think about it carefully, that's not the same thing as explaining the "why."
2006-08-20 10:31:41 · answer #2 · answered by ExtraCrispyTrick 1 · 0⤊ 0⤋
Dissolving Solutes
2016-12-18 07:41:14 · answer #3 · answered by ? 4 · 0⤊ 0⤋
The reactions taking place are not same.some are exothermic they liberate heat and some are endothermic ,they absorb heat.
2006-08-20 14:28:40 · answer #4 · answered by moosa 5 · 0⤊ 0⤋