This lab illustrates that density represents a special type of proportional relationship that relates two different measurements of the amount of a given substance present, mass and volume. Like the mass relationships such as grams per penny established in the Balance Lab, the density of a substance is the same no matter how much of it you have. Thus density, an intensive quantity, can be considered a property of a substance. You will encounter many more of these intensive properties as you proceed through the course. In each case, the relationship they establish will be linear with a y-intercept of zero. The more practice you get at recognizing and using these relationships, the easier your studying will become.