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Why is Ice Less Dense than Water??


apollo2011

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The other day I was wondering, normally, matter in a solid form is more dense than that same matter in liquid or gas form. So why is it that water's solid form, ice, is less dense than water itself? Steam or water in the form of a gas is certainly not more dense than water. Or is it?

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Steam is not more dense than water.

I believe ice floats on water not because it is less dense, but because it's cold and wants to get out.

Just kidding.

Actually, the ice forms a "framework" of water molecules, which are interconnected, and makes it solid. However, this framework spaces the molecules out more than it would in the liquid form.

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It's to do with the structure of water as a solid, vs the structure of water as a liquid.

 

The crystal formed by water is reasonably spread out because of the way that water forms bonds, compared to how it works as a liquid.

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Bismuth! My favorite element. It is less dense as a solid. So as a result, when it cools to its solid form it expands. Bismuth is also the heaviest element with a stable isotope. Its also very diamagnetic and you can make bismuth crystals with it. Not to mention it’s the main ingredient in Pepto-Bismol!

 

I thought waters density was 1 because they use it as a reference?

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Bismuth is also the heaviest element with a stable isotope

 

Sorry? Bismuth (Bi, z = 83) is behind polonium, Astatine, Radon and the entire actinide series so I dont see how it can be the 'heaviest element'.

 

Its also very diamagnetic and you can make bismuth crystals with it.

 

Whut?

 

I thought waters density was 1

 

Correct, the density of water is 1 kg per cubic decimetre (litre) and ice has a density of less than 1. this is due primarily to hydrogen bonding in water molecules. Google for more.

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apollo2011 said in post # :

For intsance, it just so happens that its density (in liquid form) is 1.

 

Actually, it doesn't. The definition of those terms mean's it's 1.

 

It's like saying 'What's the chance of the speed of light being exactly 299792458ms^-1?' when that's what the meter was standardised to mean.

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No its not, if you read MrL's post you'd see that was a wrong assumption.

 

The kilogram and the metre are the two SI units in question here. Density is NOT measured using water as 1 as a reference.

 

In liquid water, hydrogen bonds link each water molecule to 3.4 other molecules. In ice, hydrogen bonds link each molecule to 4 other molecules. The molecular packing is different.

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greg1917 said in post #10 :

 

Sorry? Bismuth (Bi, z = 83) is behind polonium, Astatine, Radon and the entire actinide series so I dont see how it can be the 'heaviest element'.

 

 

 

 

I never said it was the heaviest element.

 

It has the heaviest stable nucleus; all elements past 83 have no stable isotopes.

 

Diamagnetic is the Opposite of ferromagnetic (i. e. it is repelled by magnets) but you need some very strong neodymium magnets to see this.

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greg1917 said in post # :

No its not, if you read MrL's post you'd see that was a wrong assumption.

 

The kilogram and the metre are the two SI units in question here. Density is NOT measured using water as 1 as a reference.

 

In liquid water, hydrogen bonds link each water molecule to 3.4 other molecules. In ice, hydrogen bonds link each molecule to 4 other molecules. The molecular packing is different.

 

I don't understand. What I meant is, is it coincidentally 1 (any unit) or does water have a density of 1 because when density was discovered, 1 (any unit) was water?

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it was designated as 1 arbitrarily, as was the concept of the kilogram all the units we derive our measurements on are based on known constants. the idea was that no matter where you were a kilo would weigh exactly that as compared to water at standard conditions.

the scale of celcius 0 to 100 is based on the MP and BP of water too.

at some point all measurements need a common frame of reference, it was decided that water was the ideal :)

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