Evidence of Chemical Reaction
Signs of Chemical Change
Chemical change
Any change that results in the formation of new chemical substances. At the molecular level, chemical change involves making or breaking of bonds between atoms and chemical properties of reactants are changed. We cannot easily see chemical properties, but we can tell when they are being altered in a chemical reaction by looking out for certain signs.
Production of Light or Heat
Change in Color
Formation of Precipitate
Chemical vs Physical
A chemical change is different from a physical change because it cannot be easily undone. During a physical change, physical properties that we can easily observe are altered but can be easily reversed. The identity of the substance remains the same, it only appears different.
Dissolving Solutes
We could evaporate the water and regain the salt
(http://www.middleschoolchemistry.com/lessonplans/chapter5/lesson3)
Phase Changes
No matter what phase, water's chemical formula remains the same, H20
Beautiful Chemical Reactions