Which property of a substance affects how much weight it has at a given volume?

The property of a substance that affects how much weight it has at a given volume is density. Density is defined as mass per unit volume, typically expressed in units such as grams per cubic centimeter (g/cm³) or pounds per cubic foot (lb/ft³). It provides a direct relationship between how much matter (mass) is present in a specified space (volume). Therefore, if you know the density of a substance, you can easily calculate its weight when you know its volume.

For example, if two substances occupy the same volume but have different densities, the substance with the higher density will weigh more because it contains more mass in that volume. By understanding density, you are able to predict the behavior of materials under varying conditions, which is crucial in applications like piping systems, where the weight of fluid can affect the design and support requirements.

Viscosity, while important for understanding how fluids flow, refers to the resistance to flow rather than weight. Temperature can influence density but does not directly determine the weight of a substance at a given volume. Vapor pressure is a property related to the tendency of a substance to evaporate, which has no direct correlation with its weight at a specific volume.