Example

Let’s say we have 1.211 g of a gas that occupies a volume of 0.677 L at a temperature of 23°C (296 K) and a pressure of 0.987 atm. The molar mass would be calculated as follows:

\( M = \frac{1.211 \times 0.0821 \times 296}{0.987 \times 0.677} = 44.0 \, \text{g/mol} \)

The moles would then be \( n = \frac{1.211}{44.0} = 0.0275 \, \text{mol} \), or 27.5 mmol, 27,500 μmol, etc., depending on the unit selected.

FAQs

What is the molar mass of a gas?

The molar mass of a gas is the mass of one mole of the gas, typically expressed in grams per mole (g/mol). It can be calculated using the ideal gas law if you know the mass, pressure, volume, and temperature of the gas.

How do I calculate the molar mass of a gas?

Use the formula \( M = \frac{mRT}{PV} \), where \( m \) is the mass of the gas (g), \( R \) is the ideal gas constant (0.0821 L·atm/(mol·K)), \( T \) is the temperature in Kelvin, \( P \) is the pressure in atm, and \( V \) is the volume in liters. Ensure all units match the value of \( R \), or use unit conversions as provided in the calculator.

What is the ideal gas constant?

The ideal gas constant (\( R \)) is 0.0821 L·atm/(mol·K) when using pressure in atm, volume in liters, and temperature in Kelvin. It relates the energy scale to the temperature scale for an ideal gas.

How do I find the number of moles in a gas?

You can find the number of moles (\( n \)) using the formula \( n = \frac{m}{M} \), where \( m \) is the mass of the gas (g) and \( M \) is the molar mass (g/mol) calculated from the ideal gas law. Use unit conversions if necessary, and select the desired unit (mol, mmol, μmol, nmol, pmol) from the dropdown.