What is the term for the mass per unit volume of a substance?

The term for the mass per unit volume of a substance is density. Density is a key physical property that describes how much mass is contained in a given volume. It is commonly expressed in units like grams per cubic centimeter (g/cm³) or kilograms per liter (kg/L). Understanding density is crucial in various applications, such as determining whether an object will float or sink in a fluid, calculating material quantities, and understanding mixtures in chemistry.

Weight refers to the gravitational force acting on an object and is different from density, which relates specifically to the mass and volume of a substance. Concentration pertains to the amount of a substance within a particular volume of solution, which is also distinct from density. Mass is simply the quantity of matter in an object and does not reflect how that mass is distributed in relation to volume. Hence, density is the most accurate term for the relationship between mass and volume.