What happens during an exothermic reaction?

A) Energy is absorbed, and the temperature decreases.
B) Energy is released, and the temperature increases.
C) No energy changes occur; everything stays the same.
D) The reaction only involves mixing substances.

Scenario:
You conduct an experiment by mixing ammonium nitrate (NH₄NO₃) with water. After mixing, you notice that the solution feels cold to the touch, and the temperature of the mixture decreases.

Question:
What do these observations indicate about the type of reaction taking place? Do you think this is an endothermic reaction? Explain your reasoning.

Scenario:

A student conducts two experiments:

1. Experiment 1: Solid ammonium nitrate (NH₄NO₃) is mixed with water in a calorimeter. The temperature of the solution decreases, and the solution feels cold to the touch.

2. Experiment 2: Solid calcium chloride (CaCl₂) is mixed with water, and the temperature of the solution increases, making the solution feel warm.

Question:

Using the Law of Conservation of Energy, explain what is happening at the molecular level during these reactions. Identify which reaction is endothermic and which is exothermic, and describe the energy changes involved. How do the temperature changes and sensory observations (feeling cold or warm) support your conclusions? Additionally, discuss how these types of reactions are applied in real-world scenarios, such as in cold packs or heating pads.

What did I learn?

What was the most challenging part?

What can I improve next time?