# Pressure Calculations through Volume Differences

1. Sep 24, 2014

### EthanSchrag

Recently i've been researching the pressurization of water through the releasing of the waters of hydration in hydrates. The goal is to create a volume difference inside a container of fixed volume, basically the volume of the contents should be greater than the volume of the container in order to create pressure. Mathematically this works out and theoretically you can get a volume of 113.21ml from 100ml of a hydrate. But i don't know what to do with these numbers. I want an overall pressure and i'm assuming you can get one from them but i don't know exactly how to calculate it (Is this kind of pressurization of water even possible?). Help would be appreciated.

2. Aug 6, 2016

### Simon Bridge

Welcome to PF;
You realise that the statement " volume difference inside a container of fixed volume" is a contradiction and " the volume of the contents should be greater than the volume of the container in order to create pressure" does not make sense.
... you seem to want to force more water into an existing volume than the volume can contain, ie. increasing the density of the contained water?
So the short answer is "no". Though the water may contain something else that is more compressible.
However, it could be that you are just not communicating clearly - can you provide a reference for the process you want to study?

3. Aug 16, 2016

### Outhouse Philosopher

Every form of matter has sub-atomic space that can be compressed to a greater density. Water is no exception but the pressure required would likely be greater than a fixed size container can structurally withstand. For all practical purposes water cannot be compressed.

4. Aug 16, 2016

### nasu

Well, sending ultrasound through water is a practical enough purpose.
If water weren't compressible there would be no longitudinal sound waves in it.

The compressibility of water is much higher than that of steel or aluminum. However I never seen someone saying that steel cannot be compressed (even if only "for all practical purposes").
Why is water so special? :)

5. Aug 17, 2016

### Simon Bridge

Not sure that "releasing waters of hydration" would be a useful method either... high pressure water is used in water cooled nuclear reactors where, one could argue, the water in the pipes would otherwise occupy a larger volume (as steam). I think we need details.

Also see ie.
http://water.usgs.gov/edu/compressibility.html