Certified Fire Investigator Practice Exam

Which substance has a vapor density of 1.52?

1. Butane

2. Propane

3. Methane

4. Hydrogen

The correct answer is: Propane

The substance with a vapor density of 1.52 is indeed propane. Vapor density is a measure that compares the density of a vapor to the density of air, where air is assigned a value of 1. If a substance has a vapor density greater than 1, it tends to be heavier than air and will accumulate in lower areas. Propane, which is a hydrocarbon gas used as fuel, has a vapor density of approximately 1.52, making it heavier than air. Understanding the properties of propane is critical for fire investigators for safety reasons, toxic exposure potential, and behavior during fire incidents. Conversely, both butane and methane have vapor densities that are lower than that of propane, being between 0.58 and 0.65. Hydrogen, being the lightest element, has an even lower vapor density of about 0.07. Thus, recognizing the specific vapor densities of these substances aids in emergency response and investigation, ensuring that professionals effectively handle scenarios involving flammable gases.