When two substances chemically react, a new substance is formed. The new substance may have a different color or temperature than the original substances, or may be in a different phase. There are several indicators that a chemical change has occurred, and multiple indicators may occur in a single reaction. If no added energy is required to start the reaction, then it is a spontaneous reaction, even if the reaction takes a while to progress. Stirring is not typically regarded as adding energy. A spontaneous chemical reaction does not mean the reaction happens quickly, but rather that the atoms will naturally react when placed into contact.
- Bleach and hydrogen peroxide can irritate eyes and skin
- Bleach and food coloring can stain clothing
- Notify your instructor of any spills and/or glass breakage
- It is important to wash glassware, including thermometers, between uses