What does "specific gravity" refer to in chemistry?

Specific gravity is defined as the ratio of the density of a substance to a reference density, typically that of water at a specified temperature. This measurement is dimensionless, meaning it has no units because it is a ratio of two densities. The specific gravity provides valuable information about how heavy a substance is relative to water, which can be crucial in various applications, such as determining the buoyancy of materials, assessing fluid characteristics, or performing chemical calculations.

In practical terms, for a substance with a specific gravity greater than 1, it will sink in water, while one with a specific gravity less than 1 will float. This relationship is fundamental in physical and chemical processes, especially in fields like material science, engineering, and environmental science.