1. What Is Molar Volume?

Molar volume (V_m) is the volume occupied by one mole of a substance, typically a gas, under specified conditions of temperature and pressure. It is a fundamental concept in chemistry for gas calculations.

2. Molar Volume At STP

At Standard Temperature and Pressure (STP: 0°C or 273.15 K and 1 atm), one mole of any ideal gas occupies 22.4 liters.

STP Definition:

• Temperature: 0°C (273.15 K)
• Pressure: 1 atmosphere (atm)
• Molar Volume: 22.4 L/mol

3. General Gas Law Calculation

For non-standard conditions, molar volume can be calculated using the ideal gas law:

Where:

• \( V_m \) — Molar volume (L/mol)
• \( R \) — Ideal gas constant (0.0821 L·atm/mol·K)
• \( T \) — Temperature in Kelvin (K)
• \( P \) — Pressure in atmospheres (atm)

Explanation: This equation derives from the ideal gas law PV = nRT, solving for volume per mole (V/n).

4. Using The Calculator

Instructions: Select calculation method - use "At STP" for standard conditions or "General Gas Law" for custom temperature and pressure. Enter values in the appropriate units.

5. Frequently Asked Questions (FAQ)

Q1: Why is molar volume 22.4 L/mol at STP?
A: This value comes from experimental measurements and the ideal gas law calculation at standard conditions (0°C, 1 atm).

Q2: Does molar volume change with different gases?
A: For ideal gases, molar volume is the same regardless of gas type under the same conditions. Real gases show slight variations.

Q3: What is RTP (Room Temperature and Pressure)?
A: RTP typically refers to 25°C (298 K) and 1 atm, where molar volume is approximately 24.5 L/mol.

Q4: How accurate is the ideal gas law for real gases?
A: The ideal gas law works well for most gases at moderate temperatures and pressures. Significant deviations occur at high pressures and low temperatures.

Q5: Can this calculator be used for liquids or solids?
A: No, molar volume calculations using these formulas are specific to gases. Liquids and solids have much smaller, substance-specific molar volumes.