Question

What property of density makes it useful as an aid in identifying substances?

Short answer

The property of density that makes it useful as an aid in identifying substances is its uniqueness for each substance, as it remains constant at a given temperature and pressure regardless of the sample's size or shape. This unique density value serves as a 'fingerprint' for a substance, allowing us to differentiate between substances based on their mass per unit volume and helping in determining their composition, structural properties, and purity.

Step-by-step solution

Understand Density

Density is defined as the mass of a substance per unit volume. In other words, it tells us how much mass is concentrated in a given volume of a substance. It is commonly represented by the Greek letter "ρ" (rho) and calculated using the following formula: \[ρ = \frac{m}{V}\] where \(ρ\) is the density, \(m\) is the mass, and \(V\) is the volume of the substance. Density is an important property of matter, as it can help us determine the composition and structural properties of a substance. This makes it particularly useful for identifying substances.

Density as a Unique Property

Each substance has a unique density which remains constant at a given temperature and pressure, regardless of the size or shape of the sample. This unique density value serves as a 'fingerprint' for a substance, allowing us to differentiate between substances. Thus, if we know the density of a substance and other physical properties such as color, melting point, etc., we can identify the substance with greater accuracy.

Application in Identifying Substances

In the identification of substances, density is used as a determining factor. For example, if we have a sample of a pure metal and want to find out which metal it is, by measuring its mass and volume and then calculating its density, we can compare the result with known densities of various metals to identify the given substance. Similarly, density is used to determine the purity of a substance, as the presence of impurities will cause a change in its density. In conclusion, the property of density that makes it useful as an aid in identifying substances is its uniqueness for each substance and its ability to differentiate between substances based on their mass per unit volume.