[dhulke]

Hi!

So I'm pretty confused about the effects that pressure has on water. If I increase pressure, I increase the boiling point. Likewise, if I increase pressure I increase temperature. How's that?

That's the way air-conditioning works, by increasing pressure on one side and decreasing pressure on the other this way one side gets hotter and the other gets colder. But if by increasing pressure, temperature increases, shouldn't my deodorant bottle be hot?

And if I have water and I apply pressure, shouldn't it turn to ice at some point? I'm so confused... Can anybody help me?

[mkurek]

Air conditioning operate on an an ordinary vapor-compression cycle (OVC). And you are right, the coolant goes through 4 steps. First it is compressed, then condensed, then throttled and then evaporated. But the magic behind this cycle lies in the realm of thermodynamics. Enthalpy and entropy are the two things that make this possible.

A good example of how throttling something works is to take a can of keyboard duster, turn it upside down and spray it. The can should get extremely cold.

Now your last question is best explained by looking at a phase diagram.

http://chemwiki.ucdavis.edu/Physical_Chemistry/Physical_Properties_of_Matter/Phase_Transitions/Phase_Diagrams

If you want to turn water to ice, my guess would be that if you applied A LOT of pressure, you might be able to get water to freeze at a higher temperature like 33-34 Celsius. Might be a fun little experiment to do.

[Borek]

if I increase pressure I increase temperature

This is where your problems start - it is true, but it works only for gases being compressed (more or less) adiabatically. It is not an "universal truth".

When the gas is compressed, yes, it usually gets hot. But it can be then cooled down, just because something is compressed doesn't mean it will be hot forever.

If you want to turn water to ice, my guess would be that if you applied A LOT of pressure, you might be able to get water to freeze at a higher temperature like 33-34 Celsius. Might be a fun little experiment to do.

No need for guesses, just find the phrase diagram for water. Looks like you will need around 2 GPa to solidify water at these temperatures. Something like 20000 atm.

[Vidya]

Hi!

So I'm pretty confused about the effects that pressure has on water. If I increase pressure, I increase the boiling point. Likewise, if I increase pressure I increase temperature. How's that?

What is pressure?
It is the force exerted by molecules during collision and is applicable on gases.Pressure can change the temp or state of the gases .If you apply pressure on the gases then the sate can be changed from gas to liquid.However if pressure is applied on liquids or solids then no major changes are observed because they are not compressible.

[Vidya]

Hi!
However if pressure is applied on liquids or solids then no major changes are observed because they are not compressible.

In case of liquids and solids a very high pressure is required to see the significant effect.