1. What is Vapor Density?

Definition: Vapor density is the ratio of the molar mass of a gas to the molar mass of hydrogen gas under the same conditions.

Purpose: It helps compare the density of different gases relative to hydrogen, which is the lightest gas.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( VD \) — Vapor density (unitless)
• \( M \) — Molar mass of the gas (g/mol)
• \( M_{H2} \) — Molar mass of hydrogen gas (2 g/mol)

Explanation: The vapor density indicates how many times heavier the gas is compared to hydrogen gas.

3. Importance of Vapor Density

Details: Vapor density is important in gas storage, handling, and safety considerations. Gases with vapor density less than 1 will rise, while those greater than 1 will settle.

4. Using the Calculator

Tips: Enter the molar mass of your gas and the molar mass of hydrogen (default 2 g/mol). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is hydrogen used as the reference?
A: Hydrogen is the lightest known gas, making it a convenient reference point for comparing other gases.

Q2: What does a vapor density of 1 mean?
A: A vapor density of 1 means the gas has the same density as hydrogen gas.

Q3: What's the vapor density of air?
A: Air has an average molar mass of about 28.97 g/mol, giving it a vapor density of ~14.5 relative to hydrogen.

Q4: How is vapor density used in safety?
A: It helps predict gas behavior - gases with VD < 1 will rise and disperse, while VD > 1 may accumulate in low areas.

Q5: Can vapor density be less than 1?
A: Only for gases lighter than hydrogen (like helium), which are very rare.