[Ian_Giles]

I read mention on a couple of occasions of people saying how water either begins to freeze a 3 degrees, or it is less dense when hot, more dense when cold and so on.

Water is strange stuff, it doesn't behave in the way you might expect it to, water may be less dense when it is steam, although if you could measure the density of each individual droplet of steam that would change!

When water is cold it becomes less dense (ice).

For the sake of experiment I poured very precisely, 1 pint of ice cold water into a kettle.
I then brought said pint of water to the boil, pouring it quickly into the measuring jug.

If it was less dense then that pint of water should have expanded and be showing as more than a pint of water...it wasn't...it was still on exactly the same line, if there was any difference it wasn't enough to be able to notice with the naked eye.

When other things get hot they expand, it isn't until water boils and turns to steam that it changes...

Hot water DOES make a difference when cleaning, be it windows or the washing up, but it is the way in which the grime reacts to heat that is making the biggest difference, it softens and changes the properties of whatever substance you are trying to disolve....

I'm no scientist I know, so I'm also going to do a bit of googling about the properties of water, apparently it still baffles scientists with its varies properties, it hates to change it's state!
The amount of energy needed to bring water to the boil is totally disproportionate to what would actually be expected from a substance with the 'apparent' properties that you might expect water to actually have....as I understand it anyway! :


Ian

[Ben Walker]

Water is strange stuff, it doesn't behave in the way you might expect it to, water may be less dense when it is steam, although if you could measure the density of each individual droplet of steam that would change!

When water is cold it becomes less dense (ice).

lets not confuse the different states of water. Ice is water in a different state, quite clearly. its a solid, (water crystals). and is quite rightly less dense. but its not 'water' as in a water the liquid so you can't compare the two in that way.
Steam is a gas.
The 'steam' you see coming out of the kettle is not steam, it is water. you can't see steam, like you can't see oxygen. 'Steam' from the kettle is steam that has vapourised because it has cooled to less than 100o.
you see steam in a pan of boiling water as bubbles (gas bubbles)

the temp of water is determined by the rate of vibration of its molecules. hotter- molecules vibrating more. colder- molecules vibrating less.
The more the molecules vibrate, the more space it takes up and so is less dense (hot water)
Cold water, the molecules slow down, less space , more dense.

if the molecules slow down enough they 'stop' and the water freezes, change of state. (to do with how the molecules 'line up' i guess)
speed up enough and the molecular structure breaks up and a gas is formed.
the reason why water needs a lot of energy to boil is to do with the molecular structure.

warm water will take up more dirt like a big fuffy kitchen towel absorbs more water than a sheet of copier paper.


total blag, could be wrong

 

[dai]

Whilst we are on about the properties of water, lets look at what happens when we are rinsing beading glass. I was advised to always rinse the same, beading or sheeting. From personal observation these last four months I dissagree.
I always rinse longer on beading glass, heres why. when the glass is beading and globules form, there is a surface tension around each globule. I have seen small particles moving down the glass as I rinse and being held up by the surface tension of a globule. This is what makes it possible to float a sewing needle on water. When rinsing beading glass I try and angle the brush so that the water from the jets is pushing the dirt down. On sheeting glass the force of gravity is sufficient.
I only spend half the time rinsing if the glass is sheeting perfectly.
Another interesting thing is water cannot be compressed. Hydraulics takes advantage of this property. Dai

[JM123]

On the ball Ben chan - when water freezes it's structure changes to what is called a lattice structure - think of it as a sausage lattice, layers folded over each other, much like graphite or slate.  Bet you didn't know when water freezes to -267C it goes back to liquid form.  Try and explain that - no-one can, and I mean no-one.

[D.Salkeld_Ltd]

THE TECHNOLOGY OF
WINDOW CLEANING!!!!!!!!

Maybe we should set up a National Research Centre!!!!

David Salkeld

[telboy]

FASCINATING :


TELBOY

[marc al]

 Do you lot drink? Perhaps you should start!!!

[Walter Pole]

Dihydrogen monoxide is very dangerous stuff and should be treated with the utmost of care as this website explains:

http://www.dhmo.org/

[JM123]

yeah but its not as much fun as drinking C2H5OH which unfortunately causes a reduction of H-O-H in the body leading to an increase in pressure in the cerebral cortex.

[neil100]

About to down some amber nectar, its been chilling in the garage.

Gulp,

Nel.