is sand a solid?

Question

NOT A STUPID QUESTION!- obviously one grain is a solid, but surely a whole hand full shows the properties of a liquid? e.g flowing....

Answer 1

Soil engineering treats sandy soils (which would include dry sand) as a plastic, not a liquid. Plastic is not a new state of matter, but a solid with certain analyzable properties. As another example, glaciers, even though it's made out of water, is still treated as a plastic flow. If you mix gas flow with sand, as with sandblasting, then it's another subject. However, it wouldn't be incompressible, which is an important property of liquids.

I imagine, though, sand in weightless, sparse condition in outer space could be treated as a non-ideal gas, as would be found in planetary rings.

The problem here is largely one of semantics, because if we were to definte "a new state of matter" through creative combinations of materials, we'd end up with a whole dictionary of states of matter, all of them with different properties. For example, traffic engineers even speak of the mass of cars in traffic as having a number of phases with different properties, depending on density and speeds. For the sake of nomenclature, the different states of matter assumes uniformity at the atomic scale, in which case sand is a solid.

Addendum: leryis posted a good link to the "liquid-like" properties of fluidized sand. The real question here is, are we talking about what properties sand can have under certain circumstances, or are we talking about what state of matter is sand? What state of matter is H20?

Answer 2

Yes, interesting... I think you're right, it's best to think of it as a solid that has some of the properties of a liquid- but it could be a liquid after all! Glass is supposed to be a liquid, for example, it just flows very slowly. Maybe sand is similar...but I think that it won't do things like flow through a mesh, whereas it seems liquids will.

One interesting point is that in earthquakes of a sufficient magnitude, beds of sand will liquify, and anything that happens to be on it at the time sinks as if it is in water- when next the big one comes, goodbye Chiba city!

Be interesting to see what qualified scientists have to say about this, if any of them answer you... well, Naplusultra has it right there for you. Sand is a granular particle, fantastic work!

Answer 3

Sand is definitely a solid, mainly the chemical silica or silicon dioxide.
Think of something like a lump of coal. It is solid.
Put it in a grinding machine and grind it down to the consistency of sand, or further to a fine powder. It is still the same solid but now made up of millions of minute particles.
Hope this helps.
Someone mentions that sand liquefies during an earthquake. I can't comment on that, but all solids can theoretically be liquefied at a certain temperature. It depends on the solid what that temperature would require to be for liquefication.
Think of ice, water, steam - solid, liquid, vapour (or gas)

Answer 4

Granular materials, such as sand, grain, powders, and many pharmaceuticals, are large aggregates of macroscopic, individually solid particles. However, far from being simple materials with simple properties, granular materials display an astounding range of complex behavior that often defies their categorization as either solid, liquid or gas. In many ways, we may even think of them as presenting a new, different state of matter. In the engineering community, there has been a long-standing interest in describing and predicting the response of granular materials. This is obvious from their tremendous importance for industrial processes in areas like agriculture or civil engineering. Nevertheless, there is so far no detailed understanding as it exists, e.g., for ordinary fluids. At least in part this comes about because granular materials exist far from equilibrium and in very inhomogeneous configurations. Furthermore, because of friction, they respond in highly nonlinear ways to external forcing. Over the last 10+ years, precisely these aspects have made granular materials a model system in the physics community for the understanding of many aspects of driven, non-equilibrium behavior. This talk will review some of these unusual aspects of granular materials, and will discuss both our current understanding and some new directions for future research.

Answer 5

It shows the properties of a liquid, but its still a solid. Change in phase happens only as a result of temperature change. You can break a solid into as many small pieces as you want, but unless you raise the temperature to its melting point, it will still be a solid.

Answer 6

Yeah and if you blow it from your hand it becomes a gas? No...

It's a solid - you can stand on it, and not because of surface tension. If you heated it up enough it would become liquid and you'd see the difference but basically the fact that something is in a form of small particles which can move under pressure does not mean its undergone a phase transition.

Answer 7

yes a liquid is just like a solid but has more spaced out particals same as gas. so sand is just lots of solids. see if you drop sand it will form a pile no matter how long you leave it wheras water or even treacle will take the shape of its container and be level

Answer 8

A hand full of sand is a bulk solid. Yes if you wanted to you could view it as a fluid with a viscosity and a density

Answer 9

No, sand is still a solid.. If you like, sand is made up of millions of little solids.
Gravel pours like sand, but that is obviously solid. Sand is just very small gravel.

Answer 10

sand is a solid because its atomic properties differ from a liquids, and has a differnet atomic structre which clasifys it as solid. it may not be stable when sand is together, but it is stable as a particle, unlike a liquid.