Is glass a liquid?

Question

Someone please help with this question for my chemistry class. Is glass a liquid? 

Answer 1

Glass is an amorphous solid.  It does not have a crystal structure, but it is still a solid.

 

Answer 2

For a liquid, if we can't perceive any measurable flow, does it matter if we can extrapolate it and show it's negligible? That's poor logical support! Rather, put some isotopically stable ions on it, and check if they show signs of incorporation (i.e. migration of paricles => liquid characteristic).

Another way of thinking of this issue, is that solid/liquid/gas are convenient descriptions for most *pure* materials. Bulk properties become more entangled across this spectrum when you have complex, variable mixtures such as typical glasses. And the boundaries of physical properties can become blurred in other ways -- such as at a critical point.

Answer 3

On another point all together, before it was discovered that that amorphous state is type of solid state, scientists erroneously assumed that it was a liquid of extremely high viscosity. Indeed, highly stable amorphous solids do behave like a super viscous liquid if a long period of time passes without them crystalizing. This can be seen in old window panes that have non-uniform thickness, as can be seen when you look through them and see objects a bit distorted. As a result, early scientists used the term "super-cooled liquid".

Today there are three types of solid recognized, amorphous, quasicrystals, and crystals.

As for a super-cooled liquid, it is a liquid that has been cooled below freezing point without actually freezing. If a super-cooled liquid is disturbed, it immediately begins to freeze solid.

One other feature of amorphous solids, is that when it begins to crystallize, it becomes brittle at the point where the process starts. This is due to building stress at the site. If you touch the amorphous object, even gently, at such a point, it can spontaneously shatter.

Answer 4

Matt and John are correct, it is a solid.

I heard from a couple of teachers in high school that it is a very viscous liquid, and that this is evidenced by the windows in old churches, where the glass is thicker at the bottom than the top. This is supposedly due to the glass flowing down toward the base of the window over time, but it's much more likely that the windows were originally made in this way.

Some materials may appear to be solid at room temperature, but are actually very viscous liquids. For example, the pitch drop experiment - in 80 years only eight drops have fallen: http://smp.uq.edu.au/content/pitch-drop-experiment - you can even watch the live (and very boring) video of it.

Answer 5

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