Question

People use self-warming and self-cooling devices for many purposes such as keeping drinks cold or food warm. Medical professionals also use these types of devices to store medicines and other substances that need to stay colder than room temperature. These cooling and warming devices use a chemical reaction to produce their chilling and warming effects. Compounds combine in endothermic (heat absorbing) or exothermic (heat releasing) reactions within these devices to help them keep items cool or warm.

Jacob and Natalie are asked by their science teacher to design a warming or cooling device. They decide to design a cold pack that can be used to help keep food cool. Jacob and Natalie read about different substances that can be used inside cold packs and learn that most cold packs use endothermic reactions to cool objects. They find the table below while researching.



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Which sample uses the substance(s) that Jacob and Natalie should use to make a cold pack that will do the BEST job of keeping food cool?


Sample 1, because it absorbs the most energy


Sample 2, because it absorbs the most energy


Sample 3, because it absorbs the least energy


Sample 4, because it absorbs the least energy

Answer 1

I can’t see the table image you mentioned. But the correct choice conceptually is: pick the sample that undergoes the most endothermic reaction (i.e., absorbs the most energy), because that will remove the most heat from the food.

If you paste the table (or the ΔH values) I’ll tell you which numbered sample that is.