Density is an intrinsic physical property of matter defined as its mass per unit volume. It serves as a vital identifier for identifying pure chemical elements and compounds.
1. Formula Definition
The mathematical description of density is formulated as:
Density Equation:
$$\rho = \frac{m}{V}$$
Where $\rho$ is density ($\text{g/cm}^3$ or $\text{g/mL}$), $m$ is mass ($\text{g}$), and $V$ is volume ($\text{cm}^3$ or $\text{mL}$).
2. Volume Displacement (Archimedes' Principle)
To measure the volume of irregularly shaped solids, scientists utilize **liquid displacement**. When a completely submerged solid is dropped into a cylinder:
$$V_{\text{object}} = V_{\text{final}} - V_{\text{initial}}$$
The volume of fluid displaced is exactly equal to the volume of the fully submerged solid sample. This occurs because two distinct objects of matter cannot occupy the exact same physical space simultaneously.
3. Why Density is Intrinsic?
Intrinsic properties do not depend on the quantity of sample present. Whether you have $1 \text{ gram}$ of pure gold or $10 \text{ kilograms}$, the calculated density remains exactly $19.30 \text{ g/cm}^3$ at standard laboratory temperature and pressure. This constant property makes density analysis one of the oldest methods for gold purifications and gem verification.