[jayd265]

Hi, i have a chemistry project due in a few weeks and i was wondering if i could get some ideas on where to start. i have to get two two liter bottles and fill one with water. and then put them side by side. next i have to somehow empty the full bottle into the other bottle in less than 9 seconds for a passing grade. any ideas?

[Donaldson Tan]

try making a vacuum in the empty bottle

[mithrilhack]

according to the infomercials, you can make the water go faster if you spin the bottle. hmm

[hmx9123]

Sounds more like a physics project to me.

Anyway, take a rubber stopper with two holes; one is large, the other smallish.  To the large one, attach a semi-flexible hose, something that will make a good seal, but not get crushed or pushed out easily.  It has to be able to bend into the opening of the other bottle.  Now, take that large hose and fit it so that it fits to the bottom of the 2L bottle with the water.

For the smaller hole, make it out of some sort of tubing that can withstand a reasonable amount of pressure, but is still reasonably flexible and can make a good seal.  It doesn't have to go far into the bottle at all.  Attach one end to a tank of pressurised gas.  Turn on the pressure.  You'll blast the water out of that container.  You'll need to work on the pressure settings to get it right, but it can be transferred very fast.  This is the principle of using a canula in air-sensitive chemistry (Schlenk technique).  It's used all the time with glass vessels, needles, etc.  In your case, if you make the diameter of the hose big enough, you should be able to dump the contents of one container into the other very rapidly.

The problem with this is that you may not have access to compressed air or the like.  Check your fume hoods and see if they have a compressed air or nitrogen outlet.  Those are your best bet.  Gas jets, in addition to emitting flammable gasses, are absolutely useless because their pressure is incredibly low.

Be careful not to over pressurize the plastic bottle, too.  You start using cylinder gasses and you can blow a bottle up with no problem pretty quick.

[Donaldson Tan]

there are physical and chemical methods to create vacuum.

one other mean of creating vaccuum is to fill a bottle with hot air. when the hot air cool, it creates a vaccuum. filling a bottle with higly soluble gas and an appropriate solvent creates vaccuum as well. moreover, solution transfer can be made more efficient by swirling the solution as well.

[hmx9123]

The problem with vacuum is that it sounds like the vac would collapse the bottle, as they're most likely 2L plastic soda bottles.  Maybe it could handle some low vac, but I doubt you could empty a bottle in 9 seconds.  Those bottles are much more tolerant to pressure.