apollo2011 Posted February 11, 2004 Posted February 11, 2004 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?
Cap'n Refsmmat Posted February 11, 2004 Posted February 11, 2004 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.
apollo2011 Posted February 11, 2004 Author Posted February 11, 2004 OHHHHH! I get it now. Thanks for the quick reply!
JaKiri Posted February 11, 2004 Posted February 11, 2004 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.
apollo2011 Posted February 12, 2004 Author Posted February 12, 2004 Are there any other forms of matter that have a less dense solid than the liquid?
apollo2011 Posted February 12, 2004 Author Posted February 12, 2004 Interesting. Water seems to have many unique and interesting properties. For intsance, it just so happens that its density (in liquid form) is 1. Its kind of odd that something so ordinary can be so interesting from a scientific standpoint.
Lance Posted February 12, 2004 Posted February 12, 2004 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?
alt_f13 Posted February 12, 2004 Posted February 12, 2004 Haha yah, I think so... Aren't density units kg/m^3 ? 1 does not make sense on its own... thats like saying "What's the distance between Beetleguise and Uranus?" "6"
greg1917 Posted February 12, 2004 Posted February 12, 2004 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.
agaubr Posted February 12, 2004 Posted February 12, 2004 Density being mass/volume is temperature dependent so water with 1 g/cc or 1g/ml is at a specific temeprature usually 25C. Ag
JaKiri Posted February 12, 2004 Posted February 12, 2004 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.
apollo2011 Posted February 12, 2004 Author Posted February 12, 2004 So density is measured based on water being 1g/mL? interesting.
greg1917 Posted February 13, 2004 Posted February 13, 2004 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.
Lance Posted February 13, 2004 Posted February 13, 2004 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.
YT2095 Posted February 13, 2004 Posted February 13, 2004 1 is taken under ideal and fixed standard conditions, 1 atmosphere (sea level), at MP 298 Kelvin. M/ g mol^-1 =18.0 and p(298K)= gr cm^3 is the 1.00 you were after
apollo2011 Posted February 13, 2004 Author Posted February 13, 2004 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?
Cap'n Refsmmat Posted February 13, 2004 Posted February 13, 2004 apollo2011 said in post # : 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? It's a coincidence. That's because of the way they measure a millilleter.
YT2095 Posted February 14, 2004 Posted February 14, 2004 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
Sayonara Posted February 14, 2004 Posted February 14, 2004 Isn't 1 cubic meter of water at 25c the basis for the tonne? Or something...
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