Final answer:
Density is the term used to describe the quantity of matter per unit volume. It is the ratio of mass-to-volume and is crucial for understanding the properties of different substances and their behavior in various physical situations.
Step-by-step explanation:
The quantity of matter per unit volume is known as density. Density is essentially the mass divided by the volume, an important property measured by chemists. To calculate the density of a substance, for instance iron, one would need to divide the mass of the iron by its volume. If we have a mass of 23.4 grams and a volume of 3.00 cm³, this would result in a density calculation straightforwardly derived from the mass-to-volume ratio.
It is critical to note that in order to properly express a physical quantity, not only a number is required but also a proper unit. This ensures that the quantity is understood within a specific context or scale, such as in measuring distances or calculating density.
The understanding of density is crucial for various scientific applications. For example, comparing the density of different materials can help explain why some objects sink or float when placed in water, and it plays a role in stoichiometric calculations involving liquid reactants and/or products.