If you have two different containers filled with two different gasses at the same temperature, would they have less pressure when connected to each other? Dalton's law states that each of the gases behave independently when it comes to pressure as they fill the space as if they were the only gas occupying it. So, my thought is trying to understand a concept of this in action. If I have two tanks hooked together holding the same pressure and temperature with different gasses. When I open them to each other, will the individual gasses then expand throughout the now bigger volume, and each have a lower partial pressure? The way this is always explained seems like this would be the case. I have a very hard time believing it, and am hoping that I am hopelessly wrong and one of you out there knows how this would really work.