Question

Which of the previous problems are exothermic and which are endothermic?

1) Problem 1 is exothermic and Problem 2 is endothermic
2) Problem 1 is endothermic and Problem 2 is exothermic
3) Both Problem 1 and Problem 2 are exothermic
4) Both Problem 1 and Problem 2 are endothermic

Answer 1

To determine if a chemical reaction is exothermic or endothermic, we analyze the energy change in the reaction. If energy is released, it is exothermic, and if energy is absorbed, it is endothermic.

Step-by-step explanation:

In order to determine if a chemical reaction is exothermic or endothermic, we need to analyze the energy change in the reaction. If energy is released or given off by the reaction, it is exothermic. On the other hand, if energy is absorbed by the reaction, it is endothermic.

In the given examples:

• Problem 1: 2H₂(g) + O₂(g) → 2H₂O(l) + 135 kcal
  This reaction releases 135 kcal of energy, so it is exothermic.
• Problem 2: N₂(g) + O₂(g) + 45 kcal → 2NO(g)
  This reaction absorbs 45 kcal of energy, so it is endothermic.