Physical and Chemical Changes

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. For further information, please refer to Properties of Matter.

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

Common Physical Changes

Texture

The texture of a substance can differ with a physical change. For example, if a piece of wood was sanded, waxed, and polished, it would have a very different texture than it initially had as a rough piece of wood.

Rough Wood                                                          Finished Wood

    

Color

The changing of color of a substance is not necessarily an indicator of a chemical change. For example, changing the color of a metal does not change its physical properties. However, in a chemical reaction, a color change is usually an indicator that a reaction is occurring. The guy painting the metal car is not changing the composition of the metallic substance.

Painting a Car

Temperature

Although we cannot see temperature change, unless if a change of state is occurring, it is a physical change.

 

One cannot see the pan physically changing shape, color, texture, or any of the other physical properties. However, if one were to touch the pan, it would be incredibly hot and could cause a burn. Sitting idle in a cupboard, this pan would be cold. One cannot assess this change only through visual exposure; the use of a thermometer or other instrument is necessary.

Shape

The shape of an object can be changed and the object will still remain true to its chemical composition. For example, if one were to fold money, as shown by the figure below, the money is still chemically the same.

To more understand about materials changes you can see this ppt: