Hi everyone, I have been mulling over the relationship between pressure and boiling for some time, and I am still slightly confused. I shall attempt to provide an overview of my current understanding in the hope that I can get some corrections/clarification on my current conceptual understanding. I shall start with the following: Imagine I have some fixed amount of water, say 1 mole, in the gaseous state. I apply an external pressure to this mole of water, and the gaseous water applies its own pressure on the sorroundings. It would seem to me that, if the external pressure is greater, then the gaseous water will be compressed. Let's say that the external pressure is greater. The gaseous water is compressed and begins to condense in to the liquid state. As it is compressed, it exerts increasing pressure on the surroundings. Let's say that I can apply sufficient external pressure to force the water in to a liquid state, but that the external pressure I can apply is limited. At some point, the pressure the water applies to the surrounding should equal the external pressure; at this point, the water ceases to be compressed. It seems to me that this would have to be the case: if the external pressure was greater, then the liquid water would continue to compress. Okay, so the two are equal, the pressure that the water applies to its surroundings (I am going to call this internal pressure) is equal to the pressure from the surroundings (I am going to call this external pressure). Now I am going to heat the liquid water, increasing its thermal energy and increasing its internal pressure. It therefore begins to exceed the external pressure and expands. As its volume increases, its pressure decreases; if it again equals the external pressure, it will cease to expand. If it expands sufficiently, the pressure within the bulk of the liquid should drop enough for the liquid water to enter the gas phase. This is what boiling is. Does this explanation in anyway make sense? I have a sneaking suspicion it is wrong, but I am not sure how. Thanks for any responses.