Chemical Change vs. Physical Change

Physical changes are limited to changes that result in a difference in display without changing the composition. Some common changes (but not limited to) are:

• Texture
• Color
• Temperature
• Shape
• Change of State (Boiling Point and Melting Point are significant factors in determining this change.)

Physical properties include many other aspects of a substance. The following are (but not limited to) physical properties.

• Luster
• Malleability
• Ability to be drawn into a thin wire
• Density
• Viscosity
• Solubility
• Mass
• Volume

Any change in these physical properties is referred to as a physical change. 

Chemical changes, on the other hand, are quite different. A chemical change occurs when the substance's composition is changed. When bonds are broken and new ones are formed a chemical change occurs. The following are indicators of chemical changes:

• Change in Temperature
• Change in Color
• Noticeable Odor (after reaction has begun)
• Formation of a Precipitate
• Formation of Bubbles

Note: When two or more reactants are mixed and a change in temperature, color, etc. is noticed, a chemical reaction is probably occurring. These are not definite indicators; a chemical reaction may not be occurring. A change in color is not always a chemical change. If one were to change the color of a substance in a non-chemical reaction scenario, such as painting a car, the change is physical and not chemical. This is because the composition of the car has not changed. Also, changes in temperature or color can be a consequence of both: physical and chemical changes. In order to decide, we need to understand the cause of the change.