In Lesson 2: Breaking Ionic Bonds Lab Activity, we recorded the temperature of water as different ionic solids were added to the beaker. We observed a temperature decrease for each of the five ionic solids.

The ionic bonds of ionic solids (the system) are broken when placed in water (the surroundings) causing a decrease in the overall temperature of the water. The decrease in temperature is is due to the transfer of kinetic energy from the surroundings to the system in order to break the bonds of the ionic compound. Temperature decreasing when bonds are broken is an endothermic process.

Definitions:

Endothermic - An endothermic process absorbs energy from its surroundings, usually in the form of heat.

Exothermic - An exothermic process releases energy from the system to its surroundings, usually in the form of heat.