 Chemists are often faced with the task of identifying different substances. How do you identify the two colorless liquids in the unlabeled bottles? Is one water and one gasoline an important distinction to make if you plan to heat them or put them in the tank of your car? Are the two gray cylinders the same metal? Are they aluminum? Are they nickel? Are they solid? Are they hollow? Can you tell the difference between a United States quarter and a Canadian quarter? A magnet can? Are the two cylinders a pure metal? Are they alloys? Is the spoon sterling silver or is it stainless steel? Can you tell the difference between cellulose and cellulose nitrate? A hot stirring rod can. In Chapter 2, you will learn about chemical and physical properties and you will learn how to use these properties to identify a particular substance.