if water,here on earth is placed in an ever expanding mechanically induced vacuum,when will ice form?

Question

i am trying to develop a theory based on a device that works both on compression an extreem vacum of pure water.and the intention to benefit the public in a public forum

Answer 1

Yes, the water will freeze if no heat is added as the pressure is lowered. I have seen this done in a physics class. A dish of water is placed in a vacuum chamber and the pump is started. As the pressure gets lower, the water boils, but it is boiling at low temperature, it isn't getting hot. After a while, the boiling water freezes solid.

Answer 2

If completely pure, then ice tends not to form on water at any pressure OR temp - amazingly, water can stay liquid WAAAY past zero C providing it is completely pure and the container incredibly smooth.

Back to your question. A vacuum can actually make water BOIL at room temperature, so freezing is perhaps unlikely. I note the reply from a previous person who said it boiled and the sunndely froze, I am puzzled by that - as it is the boiling method that lets refrigeration engineers remove moisture from pipes - if the water stopped boiing and just froze, they would not manage to do the job.

You have not mentioned at what temperature your water is.

I also HATE to disuade folks original thoughts BUT your idea may need a little re-working because the moment the water starts to boil in the vacuum, it is no loger a vacuum - it is water vapour albeit perhaps at low pressure.

With compression, boiling point can be delayed significantly (hence pressure cookers etc), but unsure about freezing point and if affected under pressure.

Answer 3

It depends on how much water you have, what temperature it is at and what your vacuum level is. The reason the water is cooling down is that as the water vaporizes, the energy required is coming from the liquid water. That is why the amount of water and its temperature matters. One thing you should look up is a phase diagram of water. It will show you what phase water will be at for various pressures and temperatures. It is readily available on the internet.

Answer 4

Does it have a bag? Or is it the canister kind?