# The Pressure in Interstellar Space.

• TOMMiB
In summary: Values_of_the_gas_constantIn summary, for a gas mixture of H and He molecules in a 1m^3 volume, with n = 11000 based on the number of molecules and using the ideal gas law P = nRT/V, the pressure of the gas at a temperature of 80K is calculated to be 7.32x10^6 Pa. However, considering that the gas is in a high vacuum, this value seems to be too high and should be rechecked by verifying the units used for R and ensuring that the resulting pressure is in atmospheric pressure.
TOMMiB
Homework Statement
Interstellar gas consists of a mixture of H and He molecules (10^4) and (10^3) respectively (in a 1m^3 volume). What is the pressure of the gas if the temperature is 80K?
Relevant Equations
PV = nRT
n = 11000 because n = N/V and V = 1m^3.

Using P = nRT/V I get that P = 7.32x10^6 Pa.

considering that the gas is in a high vacuum, this value seems far too high to be true.

TOMMiB said:
Homework Statement: Interstellar gas consists of a mixture of H and He molecules (10^4) and (10^3) respectively (in a 1m^3 volume). What is the pressure of the gas if the temperature is 80K?
Homework Equations: PV = nRT

n = 11000 because n = N/V and V = 1m^3.

Using P = nRT/V I get that P = 7.32x10^6 Pa.

considering that the gas is in a high vacuum, this value seems far too high to be true.
What unit are you using for ##n##?

PeroK said:
What unit are you using for ##n##?
I have no unit, as it is simply the number of molecules in the system, I think.

TOMMiB said:
I have no unit, as it is simply the number of molecules in the system, I think.
You could always double check.

TOMMiB said:
I have no unit, as it is simply the number of molecules in the system, I think.
Recheck the ideal gas law. What are the different variables it contains and their units?

(Also check that you end up with atmospheric pressure for conditions relevant at the Earth’s surface.)

Yes, most importantly here is to check the units that you are using for R. If you use ##8.314 m^3 Pa K^{-1} mol^{-1}##, for example, then n should be in moles... A good source for various values of R is here:

https://en.wikipedia.org/wiki/Gas_constant

## 1. What is the pressure in interstellar space?

The pressure in interstellar space is extremely low, averaging around 10^-17 Pa. This is much lower than the pressure on Earth's surface, which is around 100,000 Pa.

## 2. How is the pressure in interstellar space measured?

The pressure in interstellar space is measured using instruments and sensors on spacecraft and telescopes. These instruments can detect the density of particles and radiation in space, which can then be used to calculate the pressure.

## 3. Why is the pressure in interstellar space so low?

The pressure in interstellar space is low because it is a vacuum, meaning there is a very low concentration of particles and matter. This is due to the vast distances between objects in space.

## 4. Does the pressure in interstellar space vary?

Yes, the pressure in interstellar space can vary depending on the location and environment. For example, the pressure may be slightly higher in areas with higher concentrations of matter, such as around stars or planets.

## 5. How does the low pressure in interstellar space affect objects in space?

The low pressure in interstellar space can have various effects on objects in space. For example, it can cause gas and dust to spread out over large distances, making it difficult for objects to collide and form larger structures. It can also affect the behavior and movement of charged particles and radiation in space.

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