called the critical point the critical point is a place where anything any pressure or temperature that is higher than the critical point there is no way the liquid the phase will exist only the substance will only exist in the gaseous phase so this actually can tell us a lot of things in terms of something which where the substance is in terms og the state of matter that it is in all right so let is look at something else this was water let is look at something else there is another phase diagram we can take about each substance has its own phase diagram this is carbon dioxide and there is a couple differences in carbon dioxide than there was in water one main difference if you look at both of them one main difference is this line here notice this line versus this line okay water is very uniqsue in the sense that it will have its solid form is more dense sorry less danse than its liquid form so as we continue to add pessure to the solid form it will actually change to a liquid state if we continue to add pressure if you notice to go up it is going to stay in at solid stat because the solid state is actually more dense than liquid state so you are going to see a line that looks like this alright notice carbon dixoide we are going to call that dry ice probabiy the reason to call it dry ice is because here we have some with dries actually with us it is for you alright the reason I call it dry ice is because we have it in a solid form but yeah it sublimates meaning it goes straight from solid to gas OK this is used sometimes in like movie studios or to make that gas that gas appearance at gaseous appearance so it to the solid state Imean creek street to the gaseous state that we call this sublimation alright so we are going to actually demonstrate what the trouble point will look like by putting dry ice in this container and seeing as we can make it liquid somehow so let me try and put my safety goggles on because safety is always first and we are going to put little pieces of coconuts is really cold so I really should not be doing that but it is not going to hurt me unless I hold it for too long. alright so what I'm going to do with this good ness.alright alritht so Im going to do with this is I'm going to close this up anf so now I have my dries in here and my day ice is sublimating as you saw before and so it is going straight to a gaseous state meet and also making the pressure inside this container much higher ok so if we look back at if you remember back at our graph you notice this s continuously sublimated okay and what we want to do is we want to continue to make the pressure high enough where it will stop sublimating and actually go to a triple point where you can see all of these at the same time and how we are going to do that it is going to lower the temperature and notice over on the side or notice the inside this container is really cold as you can see from the impressions of the bottle and also as you can imagine it is getting really pressurized in here because the gas is continuing to sublimate and it isgoing to increase the pressure inside the bottle and so hopefully we will get to the triple pointsh i can shake it up a little bit if you can see like on the side over here maybe you can see like the liquid inside here s now all three phases are existing making this the triple point you can see on the bottom like maybe some liquid here liquid co2 alright so now we're going to open the bottle and see what happens alright notice all that gas at the skate bang this tons of pressure in here is it actually at five atmospheric pressure which is five times the regular atmospheric that we actually are living in I'd sea level so actually let's go back here and just make sure we understand what will happen is here is our normal temperature around here we know that saw carbon dioxide's in the gaseous state what we did we lower the temperature by putting it in side a container and we increase the pressure as it sublimate inside the pressure and we were able to create this triple point where all three substances coexist so this graph actually tells us a lot of things about the different types of substances and different types of forms that they can actually have in pressure and temperature and how they're related you.