Is a melting candy bar exothermic?

When a candy bar melts, the solid sugar crystals in the candy bar dissolve into the liquid chocolate, releasing energy in the form of heat. This is because the bonds between the sugar crystals are weaker than the bonds between the sugar molecules and the chocolate molecules. When the sugar crystals dissolve, the energy that was holding the crystals together is released, and this energy is absorbed by the chocolate, causing it to melt.

The amount of heat released when a candy bar melts is relatively small, but it is still measurable. For example, if you melt a 100-gram candy bar, it will release about 100 calories of heat.