Some examples of physical change include ice melting, alcohol evaporating, iron rusting and salt water. A physical change is said to occur when something changes form but keeps the same chemical composition.
It is easy to differentiate between a physical and chemical change. In a physical change, the matter always stays the same and the original matter can be recovered. Salt water, for example, is made by mixing salt and water. Remove the water from the salt and once again, there is salt and water. In a physical change, the particles that make up salt water are simply rearranged, but remain the same.
In a chemical change, the old matter is no longer present and the end product is different. No matter what happens, the original matter cannot be recovered. This is because the particles are broken down and the atoms rearranged to form a new substance. For example, when a piece of paper is burned, it cannot be reformed to become a piece of paper again.
Other examples of physical changes include water evaporating, butter melting, cream being whipped and glass breaking.
Whether a physical or chemical change, mass cannot be destroyed or created. It is always present, but in a different form. Whether or not it can be reversed decides if it is a physical or chemical change.
