What is molar mass?

In simple terms, molar mass tells you how much the mass of one mole of a gas weighs. This is why a molar mass calculator is so useful – because it can quickly convert a gas into its mass per mole. The unit for this is grams per mole (g/mol) and it applies to elements, compounds and gases. When a substance is a gas, its molar mass can be determined using physical properties such as density, temperature and pressure; heavier molecules have a higher density hence a higher molar mass.

Why is density so important in a molar mass calculator?

Density measures how much mass is contained in a certain volume of gas.

At the same temperature and pressure:

• Higher density → more mass per volume → heavier molecules → larger molar mass
• Lower density → lighter molecules → smaller molar mass

This means molar mass is directly proportional to gas density when conditions are fixed.

So if you need to work out the molar mass of a gas mix, this free calculator may help you. When you have the molar mass of your gas you may want to use the ideal gas equation to calculate the gases density at a pressure. This is important if you are selecting a fan that drives a custom gas rather than air.

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