Is Glass a Solid or a Liquid? Poll

Welcome to A2K integrate. I too have heard that glass is a liquid - but not supercooled. So I'm with you.

Welcome Integrate.

The short answer is...well there isn't really a short answer.

Click here for the long answer.

Nobody has figured it out yet apparently.

Here is the conclusion from the website below.


There is no clear answer to the question "Is glass solid or liquid?". In terms of molecular dynamics and thermodynamics it is possible to justify various different views that it is a highly viscous liquid, an amorphous solid, or simply that glass is another state of matter which is neither liquid nor solid. The difference is semantic. In terms of its material properties we can do little better. There is no clear definition of the distinction between solids and highly viscous liquids. All such phases or states of matter are idealisations of real material properties. Nevertheless, from a more common sense point of view, glass should be considered a solid since it is rigid according to every day experience. The use of the term "supercooled liquid" to describe glass still persists, but is considered by many to be an unfortunate misnomer that should be avoided. In any case, claims that glass panes in old windows have deformed due to glass flow have never been substantiated. Examples of Roman glassware and calculations based on measurements of glass visco-properties indicate that these claims cannot be true. The observed features are more easily explained as a result of the imperfect methods used to make glass window panes before the float glass process was invented.

http://math.ucr.edu/home/baez/physics/General/Glass/glass.html

Re: Is Glass a Solid or a Liquid? Poll


Glass is a solid. But then again, so is water if you belly flop into it from a high enough platform.

Glass is a liquid. Even though you can't pour a gallon of it, or spill it.

Glass is a non-crystaline material with a viscosity which exceeds its potential to flow.

Welcome to A2K Integrate

And thanks for such a solid answer, rosborne.

I seem to recall hearing that any amorphous solid could be called a glass.

Sorry. It's so easy to look up on Google that I didn't really think it needed an answer. Also the fact that "supercooled liquid" was mentioned in the original question seems to indicate that someone has already Googled this one.

including doped metals. Ti doped with yttrium makes a nifty "metallic glass" . Its all in the properties. We just happen to be sitting a little South and East of glass's triple point.

bm

One the one hand, glass doesn not undergo a phase change when going from its "solid" state to a state where it flows. Without changing phases, did you change states? On the other hand, you can brittle fracture cold glass and that is clearly a material failure mode of solids. If you wanted to categorize it for the purpose of predicting its properties, I would go with solid.

Liquid!
True crystalline solids do not flow.

Glass flows.

A very old pane of glass can be seen to have become thicker on the bottom and thinner on the top.

Glass shelves bend over time, requiring them to be flipped over.

I'm sure someone can come up with a counter-example of a crystalline solid that appears to "flow", so I will first: marble (CaCO3). A sheet of marble will, in fact, bend. The mechanism is gliding within the crystals, which is not really flow.

Glass is neither a true solid nor a liquid. You could call it the 4th state of matter (+ liquid solid gaseous).

When liquids cool to their freezing point they normally form an opaque crystalline solid. The crystals nucleate and grow. A glass melt is so viscous that the molecules are slow to arrange themselves into crystal nucleii. It remains a liquid though its below its normal freezing point. (It becomes a supercooled liquid....its still possible to initiate crystallisation if its held at that temperature long enough).

As it continues to cool it becomes so viscous that it passes a temperature below which (the transformation temperature) crystallisation is not possible, and it becomes a glass. It certainly behaves like a solid for everyday purposes, but strictly speaking it is not, as it does flow like a liquid over long time scales. If you look at the bottom of a medieval pane of glass, you will see it is thicker than at the top, where it has "flowed" downwards.

Hope that helps

In nature, glasses are shock induced . Going from the last crystalline phase (stishovite) to a glass, (which flows) takes a pulse of a pressure wave creating "shocked quartz.
Such shocked quartz has the ability to, over millenia display liquid properties in the rock. The alpha quartz or coesite portions will remain in a rigid tetrahedral arrangement, just like a frame of a building but the glass portion will have bent.
So ,if we go by by Websters def, it displays properties of a solid, by molecular mechanics and thermo, its a liquid .

We often test strain gages by installing them on shelves of glass with lots of books .


NOW, some "glasses" are actually gels.

Thanks for the helpful replies guys .

It is both a particle and a wave.

First welcome Integrate I am from Nanjing. and you?


I have long been wondering that what makes glass seems to be invulnerable to so many corrosive chemical substances including H2SO4 and NaOH so that people produce equipments for chemical laboratories with glass.

What kind of substances does glass contain?

Glass is mostly silica, "JB", which, due the nature of its molecular structure, particularly unreactive - its atoms are pretty content with the way things are, and see no reason to go for a stroll or to welcome strangers.

And I've always sorta leaned toward the "Amorphous solid" thinkin'.

Oh, and steve, plasma is generally regarded the 4th state of matter

Theres a teeny bit of sodium carbonate in glasses , mostly as a "doping" agent to keep it from going crystalline. If youve ever seen "beach glass" you see that its pitted with small white pockets. Thats not from abrasion, its the sodium carbonate residues.

"gel" glass has some neat properties. It wil remain a liquid at room temp for abou 24 hrs then it sets up into a waxy like glass that , if you pour into separate lasses, will ring at a frequency determined by its temp and volume. The substances are silane and siloxane. We use this stuff to entomb radioactive materials in production of rare earths.

I once made a xylophone out of silane in a set of beakers . I was not the lab director .

fourth or fifth.... it doesnt really matter

I thought it was Brian Epstein. Oops, wrong thread.