# Compressing Water

1. Jan 28, 2007

### disregardthat

Is it true that it is very difficult to compress water in liquid form to a lower density, if so, why? It is not very heavy, and it is not forming into crystals in liquid form, as far as I know of.

2. Feb 1, 2007

### disregardthat

bump,

anyone?

I have heard it's almost impoissible to compress water. I really wonder why.

3. Feb 1, 2007

### Q_Goest

As water is compressed, density increases, not decreases. The property is known as "bulk modulus". Water is compressible, but being a liquid it is relatively incompressible. The amount it can be compressed is defined by the bulk modulus. See this hyperphysics link:
http://hyperphysics.phy-astr.gsu.edu/hbase/permot3.html

4. Feb 2, 2007

### disregardthat

Thanks for the link, and yes, I meant higher density.

5. Feb 2, 2007

### Darryl

I wouldl of assumed, that the compressibility of something would be determined by its initial density, water is more dense than air, so is harder to compress,

steal is more dense still, and even harder to compress, but any diver or submariner will tell you that water is highly compressible. but being fairly dense to start with, its harder to make it 'more' compressed.
and steal is allready very dense.

If when you compress something, (air, water or whatever), what are you doing? if you are forcing the atoms closer together, then i wonder what is in between the atoms or molecules.

if you can compress air, and put more gas molucles closer together, what is between the molecules before you compress it, (normal air pressue).

are the gaps between the moleculoes a vacuum ?

6. Jun 9, 2008

### Barack Obama

Yes Sir

Check this out...
1) The water that is at the bottom of the ocean is compressed by the weight of the water at the top, therefore the water near the ocean floor is denser than the water at the surface.

2) If you compressed water in some type of laboratory setting using a metallic sphere made of copper which was heated to extreme temperature to expand then dumped into a pool of water, the gap left open to fill the sphere with water would close over from the coolness of being dropped into a liquid cooler than the solid which would lead to the sphere shrinking and the water inside becoming compressed when in actuality the atoms of the water would find a way to bond with the copper or subatomic particles in between the atomic particles of the copper.
Whew.

Basically I think we can all agree "nature will find a way" and the water, although being compressed by method x, y, or z, will find a place to go in our extremely limited 4 dimensional plus space time.

We are only talking about water we can "see" and not the ocean of dark energy or dark matter that takes up more than 99% of what we humans consider the "visible" universe?

---CONTENT APPROVED---
by PREZIDENTAL

7. Jun 24, 2008

### per.sundqvist

Assuming we are talking about pure water, not a mixed phase with small gas bubbles, then my guess is the following: In liquid form $$H_2O$$ molequles are very small and close to their neighbours, but they are moving sufficiently to avoid bonding between two molecules. A "perfect" crystal of $$H_2O$$ would be much easier to compress (I have no idéa of what structure it would take). Note that for example steel or butter is made up of grains with space in between. Compression would then remove this empty space and the volume will shrink.

The numer $$\nu=1/2$$ is used to describe perfect incompressible materials, which gives $$\DeltaV=0$$ for any applied force.