What is the term for the ratio of the mass of a given volume of a liquid compared to the mass of an equal volume of water at the same temperature?

The term that describes the ratio of the mass of a given volume of a liquid compared to the mass of an equal volume of water at the same temperature is specific gravity. Specific gravity is a dimensionless quantity, meaning it has no units, and it helps to determine whether a liquid will float or sink when placed in water. A specific gravity less than 1 indicates that the liquid is less dense than water and will float, while a specific gravity greater than 1 indicates that the liquid is denser and will sink.

Understanding specific gravity is essential for firefighters as it aids in assessing the behavior of different liquids during fire suppression operations or spill responses. For instance, knowing whether a chemical is likely to float on water can help in planning containment strategies.

Solubility refers to how much of a solute can dissolve in a solvent at a given temperature, which is not the same as measuring density. Miscibility describes the ability of two liquids to mix uniformly in any proportion, which is also different from the concept of specific gravity. Vapor density compares the density of a vapor to that of air and, while important in understanding gases, it does not relate to the comparison between liquids and water.