- #1

Parzeevahl

- 6

- 0

- Homework Statement
- A diffuse cloud of neutral hydrogen atoms in space has a temperature of 50 K. Calculate the pressure (in Pa) and the volume (in cubic light-years) occupied by the cloud if its mass is 100 times the mass of the sun.

- Relevant Equations
- PV = NkT (k = Boltzmann constant)

Here's how I approached it. We know the total mass of the cloud, it is given. Let's call it 'M'. We can also find out the mass of a single hydrogen atom from its atomic weight. Let's call this 'm'. Then

N = M / m

is the total number of hydrogen atoms in the cloud. The temperature (T) is given - it is 50 K.

Then the gas equation becomes: PV = (M / m) * k * (50 K)

So, here are two unknown variables here that I have to find out - P and V. But I have only one equation (the gas equation above). How can I find out the other equation, since for two unknown variables we need two equations?

N = M / m

is the total number of hydrogen atoms in the cloud. The temperature (T) is given - it is 50 K.

Then the gas equation becomes: PV = (M / m) * k * (50 K)

So, here are two unknown variables here that I have to find out - P and V. But I have only one equation (the gas equation above). How can I find out the other equation, since for two unknown variables we need two equations?