Science presenter Jon Chase demonstrates an exothermic and an endothermic reaction, and explains how temperature changes can be used to identify which reaction is which. The exothermic reaction is the ...

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 ...

Every chemical reaction involves a change in energy because different substances hold different amounts of energy. During the reaction, bonds inside the substances that are reacting together must be ...

Katharina M. Fromm relates how barium and its ores went from a magical, glowing species that attracted witches and alchemists to components in a variety of compounds that are key parts of modern life.