# Pressure of outer space

I'm trying to calculate the pressure of outer space given the denisty of helium is of the order 1 atom per cm^3, temprature 3K.

1 atom per cm^3 => 10^6 per m^3.

It's a low pressure so I guess I can use the ideal gas equation. I also know the mass of a helium atom is 6.68x10^-27 kg.

What's the best route forward?

Best Regards, James.

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Hootenanny
Staff Emeritus
Gold Member
Why are you trying to calculate the pressure?

Either way you can use:
$$pV= nRT$$
where $n$ is the number of moles and $R = 8.31 J\cdot mol^{-1}\cdot K^{-1}$ and is the molar gas constant.

You will first need to convert the mass and density into a volume.
Hope this helps.

Last edited:
Hootenanny said:
Hope this helps.
That's great. Thanks.