Common experiments explore what properties of the popsicle are altered when heat is removed. Students prepare a sweetened beverage in an ice tray, along with wooden sticks and then put the combination in the freezer. The beverage hardens, forming ice around the stick. Students note the differences between the liquid form and solid form, including color, smell and taste to ascertain whether there is a chemical change. Ultimately however, it is just the physical state of the beverage that changes (liquid to solid) but the chemical properties remain the same.
Increasing the temperature of a popsicle can take the matter from solid form, to liquid form to gaseous form. Experiments ask the fundamental question of whether these changes are chemical or physical, examining the attributes of the popsicle stick and edible portions. The stick remains a solid as the beverage changes state. However, there is no change in smell or color of the beverage nor is there formation of a new substance, all of which may happen as a result of a chemical change.
An open flame is introduced into the popsicle equation, being put to the beverage and the stick. The popsicle beverage warms and melts due to an open flame but something different happens to the stick. The popsicle stick changes color as it burns, producing a strong odor, gray-white ash and black soot, or carbon. Instead of two substances, like a beverage and stick, the popsicle becomes four substances, adding ash and carbon to the list. The formation of new substances is evidence of a chemical reaction.
Measuring the weight of a popsicle stick materials before and after freezing reveals that the content of the matter remains the same. However, this is not the case when a chemical change takes place, such as the ignition of the popsicle stick. When the popsicle stick burns, your starting materials become lighter because part or all of the popsicle stick disappears, suggesting that a chemical change has occurred.