when does something sublime

[sangria1986]

when does something sublime? what is the opposite of sublimation?

suppose in a container at 1 atm, the temperature is 100 degrees celsius and ice is immediately placed in it...will it sublime?

When will steam become ice immediately? or is this something we would only have to find out in a phase diagram that would be provided on the exam?

also do we need to know what the critical point is?

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[Rabolisk]

Something sublimes when the pressure is too low for a liquid to exist. It goes directly from solid to gas, and the opposite is called deposition. For some compounds, like CO2, normal atmospheric pressure is too low for liquid to exist.

Ice would melt, then it would boil.

A phase diagram would tell you the answer.

A critical point is the point beyond which the distinction between gas and liquid no longer exists.

 

[loveoforganic]

1) When a solid substance's enviroment undergoes certain changes in temperature and pressure that allow it

2) Deposition

3) Again, at certain temperature and pressure. You'd have to look at the phase diagram. Unless it's clear they're getting at something quirky/providing a phase diagram, it's safe to assume heating water goes to steam, cooling water goes to ice, etc.

4) Yes

 

[sangria1986]

Something sublimes when the pressure is too low for a liquid to exist. It goes directly from solid to gas, and the opposite is called deposition. For some compounds, like CO2, normal atmospheric pressure is too low for liquid to exist.

Ice would melt, then it would boil.

A phase diagram would tell you the answer.

A critical point is the point beyond which the distinction between gas and liquid no longer exists.

distinction between gas and liquid no longer exists? can you expound on that? all i know is that past the critical point temperature, no amount of pressure will liquify the gas...

 

[Prateek]

distinction between gas and liquid no longer exists? can you expound on that? all i know is that past the critical point temperature, no amount of pressure will liquify the gas...

The substance will have properties of both a gas and a liquid: High density (liquid) + low viscosity (gas)

 

[methylethyl88]

beyond the critical point, it will exist as a supercritical fluid such that it can effuse around like a gas but also dissolve like a liquid at the same time.

 

[Web]

Steam is not water vapor. Steam is high temperature water droplets suspended in air, though high temperature water vapor is confusingly called steam some times.