"Distinguish between a chemical and physical changes."
During a physical change a substance keeps its chemical properties. For example, sawing of wood is a physical change. The wood is still wood only in smaller pieces. Another example of a physical change is the frezzing of water. Now we have ice. However this is still H20. Examples of physical changes include freezing, melting, condensation, boiling, evaporation, tearing, and crushing.
Mixtures are examples of physical combinations of matter. For example, A friut salad is a mixture. We still have all of the different friuts that make up the salad. This mixture can be separated by physical means. Another example of a mixture is salt water. When you go to the beach and jump into the ocean you get all covered in salt water. But after a while you are all dry with only a samll crusting of this white stuff left on your body. This white stuff is the salt from the water. By the process of evaporation the water went into the atmosphere.
During a chemical change substances react to form new substanaces. Examples of chamical changes include buring of wood, cooking of an egg, rusting of iron, and souring of milk.
Substances are often placed in categories if they react in similar ways. Examples include metal, nonmetals, and noble gases.
The law of consrvation of mass states that during a chemical reaction matter cannot be created or destroyed. In chemical reactions, the total mass of the reactants equal the total mass of the products.
