1. What is the Molar Mass Equation?

The molar mass equation calculates the molecular weight of an unknown liquid by using the ideal gas law. This method is particularly useful for volatile liquids that can be easily vaporized.

2. How Does the Calculator Work?

The calculator uses the molar mass equation:

Where:

• \( MW \) — Molar mass (g/mol)
• \( P \) — Pressure (atm)
• \( V \) — Volume (L)
• \( m \) — Mass of the vapor (g)
• \( R \) — Ideal gas constant (0.0821 L·atm/mol·K)
• \( T \) — Temperature (K)

Explanation: The equation derives from the ideal gas law (PV = nRT) combined with the definition of molar mass (MW = m/n).

3. Importance of Molar Mass Calculation

Details: Determining molar mass is essential for identifying unknown compounds, calculating stoichiometric relationships in chemical reactions, and understanding physical properties of substances.

4. Using the Calculator

Tips: Enter pressure in atm, volume in liters, mass in grams, and temperature in Kelvin. All values must be positive numbers. For best results, use data from vapor density experiments.

5. Frequently Asked Questions (FAQ)

Q1: What are typical molar mass values for organic liquids?
A: Most organic liquids have molar masses between 30-200 g/mol, though some polymers can be much higher.

Q2: Why must temperature be in Kelvin?
A: The ideal gas law requires absolute temperature (Kelvin) to maintain proportionality with other variables.

Q3: How accurate is this method?
A: With careful measurement, accuracy within 5% can be achieved, though deviations from ideal gas behavior can affect results.

Q4: Can this be used for solids?
A: No, this method requires the substance to be volatile enough to produce measurable vapor.

Q5: What if my liquid decomposes when heated?
A: This method won't work for thermally unstable compounds. Alternative methods like freezing point depression should be used.