Referring to Problems 13.37 and 13.38, which reaction is exothermic and which is endothermic? Justify your answer, and describe which reaction could be used to supply heat and which could be used to “supply cold” (which actually means to remove heat).

Data from Problem 13.37

In a chemical reaction, compound A is converted to compound B. In the process, energy is absorbed from the surroundings. Which compound is at a higher energy level? Explain your answer.

Data from Problem 13.38

In a chemical reaction, compound C is converted to compound D. In the process, energy is released into the surroundings. Which compound is at a higher energy level? Explain your answer.