Question

Determine whether each of the following isexothermic or endothermic and indicate the sign of (Delta sign) H.

a. Dry ice evaporating
b. a sparkler burning
c. the reaction that occurs in a chemical cold pack often usedto ice athletic injuries

Answer 1

A sparkler burning is an exothermic process with a negative ΔH, while the reaction in a chemical cold pack used for athletic injuries is an endothermic process with a positive ΔH.

Step-by-step explanation:

When considering chemical reactions and physical changes, we determine the nature of the process by the flow of heat. An exothermic process is one that releases heat to the surroundings, commonly observed in combustion reactions such as a sparkler burning. The heat given off can often be felt as warmth and sometimes seen as light.

In contrast, an endothermic process absorbs heat from its surroundings, leading to a decrease in temperature. A typical use case is a chemical cold pack, which, when activated, absorbs heat resulting in a cooling effect. This is due to an endothermic chemical process inside the pack, often involving the dissolution of ammonium nitrate in water.

Therefore, to address the student's questions: The burning of a sparkler is exothermic with a negative ΔH, and the reaction that occurs in a chemical cold pack is endothermic with a positive ΔH.