When ammonium nitrate is dissolved in water, energy is absorbed from the surroundings, causing a decrease in the resulting solution's temperature. Which of the following best describes this type of reaction?

A reaction that absorbs energy from the solution and decreases the solution's temperature is called and endothermic reaction. A physical change that absorbs heat can also be described as endothermic.

The opposite of endothermic is exothermic. A reaction that is exothermic releases energy to the surroundings. This is observed as an increase in the temperature of the solution.