What is the Difference Between Density and Vapour Density?

The main difference between density and vapor density lies in the fact that density measures the mass per unit volume of a substance, while vapor density is a relative value that measures the density of a substance's vapor in relation to the density of hydrogen. Here are the key differences between density and vapor density:

• Definition: Density is the ratio of a substance's mass to its volume, while vapor density is the mass of a certain volume of a substance divided by the mass of the same volume of hydrogen.
• Units: Density is usually measured in grams per cubic centimeter (g/cm³), while vapor density is a dimensionless quantity.
• Temperature Dependence: Vapor density is independent of temperature for ideal gases, while density is dependent on the temperature of the substance.
• Pressure Dependence: Pressure does not affect the vapor density of a substance, but it affects the density of the substance.
• Comparison with Air: Vapor density can be used to determine whether a gas is more or less dense than air, which is important for container storage of gases and personnel safety.

In summary, density is an absolute value that measures the mass per unit volume of a substance, while vapor density is a relative value that compares the density of a substance's vapor to the density of hydrogen. Vapor density is useful for determining the relative density of gases compared to air, which has implications for safety and storage.

Comparative Table: Density vs Vapour Density

Here is a table comparing density and vapor density:

In summary, density is an absolute value that measures the mass per unit volume of a substance, while vapor density is a relative value that compares the density of a gas or vapor to the density of hydrogen or air.