Physical & Chemical Changes
Physical Change
A Physical Change is a change in the way an object looks, but not in what the object is made of. Changing of state,
The picture above is an example of a Chemical Change (antacid in water)
Chemical & Physical Change Lab
such as a pond freezing in the winter is an example of a physical change. The appearance of the pond has changed, but the composition of the water has not changed, it is still made of hydrogen and oxygen. Changing shape is also a physical change. Like crumpling paper, cutting a banana, or slicing an apple are all examples. When you cut, tear, grind, or bend matter, you cause a physical change.
Dissolving sugar in iced tea is a physical change, which is often misconceived as a chemical change. Salt in water is also another example. When you not sure whether it is physical or chemical you can always ask yourself did the substance change composition after the change.
Chemical Change
In a Chemical Change substances are changed into different substances. Fireworks are a prime example of a chemical change. The explosions and colors are evidence of changes in compostion.
Chemical changes are often hard to spot, but there are some signs to look when determining if it is a change in
compostion. The easiest to spot is a color change. Have you ever seen an apple slice turn brown? A chemical change occurs when an apple reacts with oxygen in the air. This occurs with other fruits as well. Leaves changing colors in the fall is also a good example. Energy is another sign of a chemical change. Many substances must absorb energy to have a chemcial change. For example, what do you add to pancake batter to make it turn into a pancake? Energy in the form of heat is added. The energy is absorbed by the pancake batter as it undergoes a chemcial change and a solid pancake is the result.
Conservation of Mass
The Law of Conservation of Mass state that the total mass of amtter is the same before and after physical or chemical changes. So, matter cannot be created or destroyed.
