Not all reactions give off heat like this. In fact, some actually take in or absorb energy from their surroundings, and the reacting substances feel cold. They’re called endothermic reactions.

Two dry solids --- barium hydroxide and ammonium nitrate --- are mixed to produce an endothermic reaction. The temperature of the mixture drops approximately 45oC and is cold enough to freeze the ...

This is shown by larger energy arrows coming out of the products and smaller energy arrows going into the reactants. In this reaction, the temperature goes down, so it is endothermic. In an ...

Commercial heat packs (containing iron and water, or supersaturated sodium acetate) and cold packs (various ammonium salts) can be used to show exo- and endothermicity. Heat packs that contain iron ...

Students investigate reactions which produce a gas, form a precipitate, and cause a color change. Students also explore endothermic and exothermic reactions and do an engineering activity to design a ...

Incredibly, the reaction between iron and moist air that produces rust is a very exothermic process and generates lots of heat. Unfortunately, this particular reaction takes place so slowly that ...