Density and Relative Density

Understanding Density

Density is a measure of how much mass is contained in a given volume. It is a property of materials that helps us understand how heavy or light an object is for its size.

The formula for density $(\rho)$ is:

$$\rho = \frac{m}{V}$$

• $\rho$ = density (kg/m³)
• $m$ = mass (kg)
• $V$ = volume (m³)

Understanding Relative Density

Relative density, also known as specific gravity, is the ratio of the density of a substance to the density of a reference substance (usually water for liquids and solids). It is a dimensionless quantity.

The formula for relative density $(RD)$ is:

$$RD = \frac{\text{Density of substance}}{\text{Density of water}}$$

Since the density of water is approximately 1000 kg/m³, the relative density can be calculated as:

$$RD = \frac{\rho_{\text{substance}}}{1000}$$

Experimental Determination

• For Solids: Use a balance to find mass and a displacement method to find volume.
• For Liquids: Use a pycnometer or a graduated cylinder to measure volume and a balance for mass.