1. What is Molar Volume?

Molar volume is the volume occupied by one mole of a substance (usually a gas) at a given temperature and pressure. For ideal gases, molar volume is the same for all gases under the same conditions.

2. Standard Molar Volume (STP)

At Standard Temperature and Pressure (STP: 0°C and 1 atm), the molar volume of an ideal gas is:

This value is derived from the fact that one mole of any ideal gas occupies 22.414 liters at 0°C and 1 atmosphere pressure.

3. Ideal Gas Law Calculation

For other temperatures and pressures, 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)

Note: Temperature must be converted to Kelvin: \( T(K) = T(°C) + 273.15 \)

4. Using the Calculator

STP Calculation: Select "STP" for standard molar volume at 0°C and 1 atm.
Custom Conditions: Select "Ideal Gas Law" and enter temperature (°C) and pressure (atm) for specific conditions.

5. Frequently Asked Questions (FAQ)

Q1: What is STP?
A: STP stands for Standard Temperature and Pressure, defined as 0°C (273.15 K) and 1 atmosphere pressure.

Q2: Why is molar volume important?
A: It allows conversion between moles and volume for gases, essential in stoichiometry and gas law calculations.

Q3: Does molar volume change with different gases?
A: For ideal gases, molar volume is the same for all gases under identical conditions. Real gases show slight variations.

Q4: What is the molar volume at room temperature?
A: At 25°C and 1 atm, molar volume is approximately 24.465 L/mol using the ideal gas law.

Q5: How accurate is the ideal gas law?
A: The ideal gas law is very accurate for most gases at moderate temperatures and pressures. Deviations occur at high pressures and low temperatures.