Dry Ice/co2

[facool 0]

I know dry ice is frozen CO2 and it sublimates directly from solid to gas. My question concerns the other direction. Everything I have found on the creation of dry ice starts with liquid CO2 and high pressure. The pressurized liquid is then allowed to expand, causing dry ice to form (if I understood what I read).So my question is: Assuming you are at sea level, what happens when you take CO2 gas and cool it past it's freezing point? It seems to me that the result should still be solid CO2. But then why go through the trouble of liquid CO2 to make dry ice?

[BuffaloHelp 24]

There are three phases in thermodynamics: solid, liquid and gas.These stages are basically related to the boiling/melting point of an element. Let's say to turn H2O to gas form, it will require so much energy going from liquid to gas. And to go from solid (ice) to gas (steam), it will need to "move" to the liquid form (requires loss of energy) before becoming the gas form.So, to make CO2 from gas to solid, it would still require to go through the liquid phase. But if you start with liquid CO2 it will take shorter time to "move" to solid phase. That's all it is--to save time and energy, in a nutshell.The marketing strategy of transporting CO2 as liquid form is basically the cost saving. As per volume, liquid form can store more molecules (more volume) than in gas form.

[shadowx 0]

I may be wrong but i assume that by letting the liquid CO2 expand it loses heat and as such becomes a lot colder and get so co,ld it freezes into a solid form, you could do the same thing by using a super cold freezer machine but i think it takes more energy to cool the liquid than it does to allow it to expand so to save money and energy they cool it till its very very cold and then expand it so it gets colder and freezes solid.Like i said i might be wrong but i think im right, as a substance expands it cools and as it is compressed it heats, thats why when pumping up a bike tire the tube gets ht as the air inside is compressed.

[BuffaloHelp 24]

In the case of CO2, the natural state of this element is the form of gas.So by forcing gas (excited state) to "calm down" or give excited energy away (exothermic) this gas condenses to the liquid form. But it requires the constant energy loss (or in lower temperature) to stay as liquid form.The reason CO2 becomes solid is the basic theory of mass verses pressure. When CO2 (whether in gas or liquid) is forced to a confined space it has no where to go but be forced to stick together. This forms much more tighter molecule formation (like over crowding in a tight place) and thus forms denser format--solid. The reason it's called Dry Ice is when CO2 solid melts it leaves no trace of liquid, unlike H20 ice.Oh and by the way, CO2 solid is does not expand since it conforms to the shape of the confined space. The other substances that expand on freezing are H2O, Germanium, Gallium, Bismuth and Silicon. Any liquid that becomes denser than the solid counter part will expand.