Ideal Gas Law Calculator


Ideal Gas Law Formula

The follow equation is used to define ideal gasses:

pV = nRT

  • Where p is the pressure in Pascals (Pa)
  • n is the number of moles of substance

What are ideal gases?


  • They obey Newton’s laws of motion
  • They don’t interacted except with collisions. I.E. no chemical reactions
  • Collisions are elastic
  • It’s a large amount of substance.


How to calculate ideal gas properties

The properties of a so called ideal gas all follow the equation outlined above. Since the gas constant is already known, only 3 out of 4 properties must be known in order to calculate the missing property. For instance if you know the pressure, volume, and amount of substance you can calculate the temperature. If you know the pressure, temperature, and volume, you can calculate the amount of substance. Simply re-arrange the equation and you are off and running.

The following example will go over the steps to calculating the properties of an ideal gas. In this case specifically, we will solve for pressure.

  1. First, we must re-arrange the ideal gas equation to solve for pressure. We can simply do this by dividing both sides by volume. The result is the following: p = nrT/V.
  2. Now that we have pressure solved for in the equation, we need to find or measure the 3 other variables. This would be number of moles, temperature and volume. For this example we will assume 1 mole, 1 degree C temperature, and 1 cubic meter of volume.
ideal gas law calculator

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