1) what is the opposite of sublimation? (solid-->gas=sublimation, then gas-->solid=?)?

Question

2) why do we see bubbles when liquids start to boil?
3) what is dry ice made of?

Answer 1

Sublimation is useful both as the name for solid to gas transition and the gas to solid transition, skipping the liquid step.

http://encyclopedia.thefreedictionary.com/sublimation
http://encyclopedia.thefreedictionary.com/sublimation+(physics)

Deposition does NOT appear to be the same thing? At least I can't find a physics reference to it. In chemistry it's the depositing of substances out of solution on the surface of something... Like gold plating or something. Doesn't quite seem to mesh. But here you go, just for reference/comparison:
http://encyclopedia.thefreedictionary.com/deposition+(chemistry)

Bubbles form when regions of a liquid become energetic enough to turn into vapor, but are confined by the less dense matter around them still in the liquid state. So, a pressure bubble forms wherein the more energetic particles push apart the less energetic particles. A sphere is the most stable structure for this, thus a bubble. Eventually the particles are energetic enough their pressure increases, density decreases and they begin to rise to the surface and are then ejected into the air.

Dry ice is solid carbon dioxide, and vaporizes easily at room temperature and the range of pressures we live in.

Cheers!

Answer 2

1) Also sublimation

2) The water does not heat up evenly. Those parts where bubbles form have already absorbed enough heat to evaporate some of the water. The vapor is trapped in the liquid, forming a bubble. Eventually, the water is heated up to a more uniform temperature, so the liquid boils on the surface as well.

3) Solid Carbon Dioxide

Answer 3

sublimation

particals in the liquid (neucleation sites) become surrounded in gas molecules from the liquid-these bubles then grow as more liquid molecules go from the liquid state to the gas. the bubbles eventually become large enough to overcome the surface tension holding them to the vessel and rise through the liquid. Bubbles at the surface are just these bursting.

CO2 which sublimes directly to a gas at atmospheric pressure without passing through a liquid phase

Answer 4

1) the opposite is also called sublimation

2) odd thing about phase change is that it normally requires something to get it started at any particular point. Existing pockets of vapour act as "nucleation" sites and make the phase change easier for the molecules round about. Hence the bubbles glow.

3) Carbon dioxide, which sublimes from its frozen form into vapour if memory serves.

Answer 5

1) In at least one case we call it frost.
2) The liquid phase is unstable but more so at the liquid-gas boundary. Any bubble has such a bounday so more gas forms and the bubble expands.
3) Carbon Dioxide (CO2)

Answer 6

1. deposition
the term is also used in technologies that deposit from as to solid (eg CVD and MOCVD)

2. cavitation

3. carbon dioxide

Answer 7

it's called deposition