What is the pressure of outer space?

[capslock]

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.

 

[Hootenanny]

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.

 

[capslock]

Hope this helps.

That's great. Thanks.