A student investigates the changes that occur during two separate mixing procedures conducted in insulated containers at \(25.0\text{ }^\circ\text{C}\), as summarized in the table below.

Experiment	Procedure	Observations
1	A \(10.0\text{ g}\) sample of \(\text{NH}_4\text{NO}_3(s)\) is added to \(100.0\text{ g}\) of distilled \(\text{H}_2\text{O}(l)\).	The solid dissolves completely; the temperature of the mixture decreases to \(17.2\text{ }^\circ\text{C}\); no gas is evolved.
2	A \(10.0\text{ g}\) sample of \(\text{NaHCO}_3(s)\) is added to \(100.0\text{ g}\) of \(1.0\text{ M}\ \text{HC}_2\text{H}_3\text{O}_2(aq)\).	Vigorous bubbling occurs; the solid dissolves completely; the temperature of the mixture decreases to \(17.2\text{ }^\circ\text{C}\).

Which of the following statements and justifications best explains whether each experiment represents a physical change or a chemical change?