# Would connecting two pressurized gas tanks together exchange gases?

While the answer to the title is inevitably "Yes", allow me to clarify. I have no background in physics, so please bare with me and I'll be happy to add any clarifications requested in the comments.

If I have 2 tanks:

1. rated for 100,000 kPa, currently at 100,000 kPa, contains Gas#1
2. rated for 2,000 kPa, currently at 1,000 kPa, contains Gas#2

Let's say hypothetically their valves are connected together with an infinitely strong pipe and some form of pressure regulator that prevents Tank #2 from being pressurized beyond 2,000 kPa. Let's also say the gases inside are of equal density/volume/weight/etc.

The question is:

If I opened the valves to these 2 tanks, and Tank #1 pressurizes Tank #2, will the gases exchange between the tanks? In other words, which one of these scenarios would be correct:

Scenario 1:

Tank #1 is now at 90,000 kPa, contains Gas#1

Tank #2 is now at 2,000 kPa, contains 50/50 Gas#1/Gas#2

-

Scenario 2:

Tank #1 is now at 90,000 kPa, contains Gas#1/Gas#2 (ratio unimportant)

Tank #2 is now at 2,000 kPa, contains Gas#1/Gas#2 (ratio unimportant)

$$P(V_1+V_2)=(n_1+n_2)RT$$(for final combination).
Now for final temperature $$n_1C_1(T-T_1)=n_2C_1(T_2-T)$$ Finally solving these $$P=(R(n_1T_1+n_2T_2))/(V_1+V_2)$$ Hope this helps you.