1. Density is an intensive property: This means that density doesn't change with the amount of substance you have. A gram of gold has the same density as a kilogram of gold. This makes it a reliable characteristic for identification, as it's not affected by the size of the sample.
2. Density is often unique to a substance: Each pure substance has a specific density at a given temperature and pressure. This allows you to compare the density of an unknown sample to a database of known values and potentially identify the substance. For example, if you measure the density of a liquid and find it to be around 0.79 g/mL at room temperature, you could reasonably conclude that it's likely ethanol, as that is the density of pure ethanol.
