Jump to content

Recommended Posts

Does clay remain uniform even when you pound it, shape it or mold it with a "Pot Wheel? "

I have looked online for information and "did find" some resourceful information, but "visually" such as a "lattice" or other uniform topologies I am "very" confused.

Here is what I mean:

Here is an image:

Wikimedia-Commons.png (2000×736) (d1whtlypfis84e.cloudfront.net)

 

The reason i'm confused is in due part of the spacing in-between the particles themselves" "What Governs This?"

I guess im asking about electron configuration, or electro static attractions from particle to particle, " IE" Ionic Solids,  if this helps.. 

Here is an image:

2 (2213×1167) (mtstatic.com)

 

 

Here is my question "answered by Wikipedia" but I really would like to confirm this here, as " i was under the impression" that clay is like "glass" and glass is an "Amorphous Solid" not uniform " a " Super Cooled Fluid" and fluids are " from what I know" not Uniform rather chaotic.


Topology - Wikipedia
In mathematics, topology (from the Greek words τόπος, 'place, location', and λόγος, 'study') is concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling and bending. 

 

 

Hope I made this clear enough....Thnks In Advance!

Link to post
Share on other sites

This is really not my area of expertise, but it's probably better in the inorganic chemistry section. From what I know, clay chemistry is very complicated with lots of silicons and aluminums and clay varies a lot in mineral content, so I'm not sure if you can create exact electrostatic maps or anything like that and I'm honestly not 100% sure what you mean by "uniform". But I would think drying out the clay into the bone dry stage and firing it into the bisque stage would change molecular configurations much more than just working the clay.

Link to post
Share on other sites

  

8 hours ago, OneWorldOneNumber said:

Does clay remain uniform even when you pound it, shape it or mold it with a "Pot Wheel? "

I have looked online for information and "did find" some resourceful information, but "visually" such as a "lattice" or other uniform topologies I am "very" confused.

Here is what I mean:

Here is an image:

Wikimedia-Commons.png (2000×736) (d1whtlypfis84e.cloudfront.net)

 

The reason i'm confused is in due part of the spacing in-between the particles themselves" "What Governs This?"

I guess im asking about electron configuration, or electro static attractions from particle to particle, " IE" Ionic Solids,  if this helps.. 

Here is an image:

2 (2213×1167) (mtstatic.com)

 

 

Here is my question "answered by Wikipedia" but I really would like to confirm this here, as " i was under the impression" that clay is like "glass" and glass is an "Amorphous Solid" not uniform " a " Super Cooled Fluid" and fluids are " from what I know" not Uniform rather chaotic.


Topology - Wikipedia
In mathematics, topology (from the Greek words τόπος, 'place, location', and λόγος, 'study') is concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling and bending. 

 

 

Hope I made this clear enough....Thnks In Advance!

 

The one thing this question is not about is organic chemistry.

The chemistry of clay materials is very properly inorganic chemistry.

But I question if this is a chemistry question at all.

The term 'uniform' is a very general term that is scientifically meaningless until qualified by some context of application.

It means that all objects considered obey the same rule (or set of rules) in some context.

So a unform electrical line has the same electrical properties throughout its length in electrical theory
A uniform extension refers, in  metrology, to a standard rate of extension against gauge length
Uniform in mathematics refers to a common prioperty of members of a set, or subset.
Geologists also refer to strata a uniform, meaning composition.

But, from the reference to a potter's wheel, I think the key usage here is to be found in Rheology which refers to the mechanical properties of viscosity, cohesion and deformability.
Such information would normally reside in the discipline of soil mechanics.
These are particularly complicated for clays as a clay is made of two components.
Clay minerals and water.
Both of these contribute to the rheological (mechanical) properties of the clay.

I think that potters are like cooks, they supply the context by talking about a 'uniform consistency' which is just fine as consistency is taken to mean 'the properties of interest to me'

I have limited knowledge of the potter's wheel but I understand it is important to get the water content correct and this changes during throwing and working the clay, even before dying and eventual firing.

I agree with iNow, unform is not the totally correct term as a clay can be banded  -  ie  -  have very fine strata  - and uniform, because all the bands are repeated in the same way throughout the clay lump.
Such clay is not homogenous, a different, homogenous, clay is required by potters.
Homogenous means the composition is the same at every point in the lump.
There is no banding.

Another allied term is isotropic, which means some property is the same in all directions.
Bulk clay is isotropic in respect of the mechanical properties of the water content and the random orientation of the clay mineral particles at the molecular level.
But the minerals (molecules) themselves are not istropic.
Due to inter molecular electrical forces they have very complicated mechianical properties.
The water component is mechanicallyboth isotropic and homogenous.

The process of working the clay both removes the water and 'lines up' the clay minerals so they no longer have isotropic mechanical properties but they are still homogenous.

Does this help ?

Edited by studiot
Link to post
Share on other sites
Posted (edited)
On 3/30/2021 at 7:07 PM, iNow said:

Uniform? No. Homogenous? Yes. 

I really want to make sure i am on the same page with you..

Is homogenous something that is "balanced" or synchronized with something else?

I'm seeing elements and compounds appear to share this same property??

 

From google search:

What are some homogeneous examples?
Examples of homogeneous elements are: nitrogen in a balloon, mercury in a thermometer, or gold in an ingot.

Compounds can be homogeneous. Examples of homogeneous compounds are: carbon dioxide in a balloon, water in a bottle, or plastic forming an electric socket.

 

 

I just want to note, of the nitrogen in a balloon and carbon dioxide in a balloon and the others behave either gas like or fluid like??

Now i cannot resist to ask:

Does Homogenous also deal with " ions" like those in sodium chloride? There spacing and formation I mean.

Also, what I mean is how they " arrange" and re-arrange themselves " the atoms" I mean " at random.

 

Here is what I mean.

Sodium Chloride (NaCl) Crystal | PhysicsOpenLab

 

 

When I "visualize" something homogenous i envision this image of something x that has the same value through a topology at every point in " the mass" of the clay.

I'm not to sure if this means " without gravitational forces" from earth though because anything with mass is influenced by it.

 

 

 

166865004_221263879562672_2014673469972958364_n.jpg

On 3/31/2021 at 1:38 AM, studiot said:

  

 

The one thing this question is not about is organic chemistry.

The chemistry of clay materials is very properly inorganic chemistry.

But I question if this is a chemistry question at all.

The term 'uniform' is a very general term that is scientifically meaningless until qualified by some context of application.

It means that all objects considered obey the same rule (or set of rules) in some context.

So a unform electrical line has the same electrical properties throughout its length in electrical theory
A uniform extension refers, in  metrology, to a standard rate of extension against gauge length
Uniform in mathematics refers to a common prioperty of members of a set, or subset.
Geologists also refer to strata a uniform, meaning composition.

But, from the reference to a potter's wheel, I think the key usage here is to be found in Rheology which refers to the mechanical properties of viscosity, cohesion and deformability.
Such information would normally reside in the discipline of soil mechanics.
These are particularly complicated for clays as a clay is made of two components.
Clay minerals and water.
Both of these contribute to the rheological (mechanical) properties of the clay.

I think that potters are like cooks, they supply the context by talking about a 'uniform consistency' which is just fine as consistency is taken to mean 'the properties of interest to me'

I have limited knowledge of the potter's wheel but I understand it is important to get the water content correct and this changes during throwing and working the clay, even before dying and eventual firing.

I agree with iNow, unform is not the totally correct term as a clay can be banded  -  ie  -  have very fine strata  - and uniform, because all the bands are repeated in the same way throughout the clay lump.
Such clay is not homogenous, a different, homogenous, clay is required by potters.
Homogenous means the composition is the same at every point in the lump.
There is no banding.

Another allied term is isotropic, which means some property is the same in all directions.
Bulk clay is isotropic in respect of the mechanical properties of the water content and the random orientation of the clay mineral particles at the molecular level.
But the minerals (molecules) themselves are not istropic.
Due to inter molecular electrical forces they have very complicated mechianical properties.
The water component is mechanicallyboth isotropic and homogenous.

The process of working the clay both removes the water and 'lines up' the clay minerals so they no longer have isotropic mechanical properties but they are still homogenous.

Does this help ?

This is a great reply and thank you, I will research everything you have stated and study it in detail to further understand this..

Edited by OneWorldOneNumber
Link to post
Share on other sites
On 3/31/2021 at 1:57 AM, OneWorldOneNumber said:

Does clay remain uniform even when you pound it, shape it or mold it with a "Pot Wheel? "

I have looked online for information and "did find" some resourceful information, but "visually" such as a "lattice" or other uniform topologies I am "very" confused.

Here is what I mean:

Here is an image:

Wikimedia-Commons.png (2000×736) (d1whtlypfis84e.cloudfront.net)

 

The reason i'm confused is in due part of the spacing in-between the particles themselves" "What Governs This?"

I guess im asking about electron configuration, or electro static attractions from particle to particle, " IE" Ionic Solids,  if this helps.. 

Here is an image:

2 (2213×1167) (mtstatic.com)

 

 

Here is my question "answered by Wikipedia" but I really would like to confirm this here, as " i was under the impression" that clay is like "glass" and glass is an "Amorphous Solid" not uniform " a " Super Cooled Fluid" and fluids are " from what I know" not Uniform rather chaotic.


Topology - Wikipedia
In mathematics, topology (from the Greek words τόπος, 'place, location', and λόγος, 'study') is concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling and bending. 

 

 

Hope I made this clear enough....Thnks In Advance!

I'm not a mineralogist, but I can try to add a bit to what others have said, based on what I have quickly been able to read up.😉

Clays are made up of tiny crystals of "clay minerals" and water. The water is hydrogen-bonded to the surface of the crystals, which means it is attached by bonds that are about a tenth the strength of a full "normal" chemical bond. A crystal of dry clay mineral will tend to absorb water until there is a hydrogen bonded film of water all along its surface. 

Clay minerals are made of sandwiches of sheets of silicate tetrahedra, which have a -ve charge, with metal ions in between that have a +ve charge, thus making the whole sandwich electrically neutral, and then water molecules in between one sandwich and the next. (Though some are Danish open sandwiches with only one layer of silicate "bread" under the metal ions and nothing on the top.)  Because they have a sheet structure, these minerals easily cleave along the lines of the sheets, as mica does. What you end up with is a lot of microscopic, flat, very thin flakes of clay mineral, with water in between. It is the water that makes clay plastic, enabling you to mould it, as it allows the flat flakes to slide past one another.  In terms of chemical bonding, you have covalent bonding within and between the silicate tetrahedra, ionic bonding between the sheets of tetrahedra and the metal ions in the sandwich, and finally hydrogen bonding of water molecules along the outside of the sheets. So clays are chemically quite complicated things, dull though they may look from the outside.

So when you ask if clay is uniform or homogenous, it depends on at what level  you mean. Macroscopically it is, but at the molecular level it is made of two distinct phases, a solid mineral and liquid water - albeit much of the water is hydrogen bonded to the mineral so that it does not behave entirely like a liquid. Moulding the clay does nothing to this structure. However, drying or firing the clay will drive off most of the water, shrinking the clay and hardening it by allowing the layers to link together directly instead of being kept apart by a layer of water.

Here's a diagram I found which may help visualise it:

image.thumb.png.06cd39cc62219cfe53e95841db705da0.png

 

 

 

 

Link to post
Share on other sites
1 hour ago, exchemist said:

I'm not a mineralogist, but I can try to add a bit to what others have said, based on what I have quickly been able to read up.😉

Clays are made up of tiny crystals of "clay minerals" and water. The water is hydrogen-bonded to the surface of the crystals, which means it is attached by bonds that are about a tenth the strength of a full "normal" chemical bond. A crystal of dry clay mineral will tend to absorb water until there is a hydrogen bonded film of water all along its surface. 

Generally good stuff and a good addition/expansion of my offering, if a tad technical.  +1

However beware of the common statement that hydrogen bonds are weaker than 'normal' bonds. Some hydrogen bonds can be as strong or stronger, especially in organic chemistry.

3 hours ago, OneWorldOneNumber said:

This is a great reply and thank you, I will research everything you have stated and study it in detail to further understand this..

Glad it was of some help.

To further understand the difference between homogenous and uniform look at my diagrams of two standard sponge cakes.
A standard cake has a filling sandwiched between two slabs of sponge.

Cake A is uniform but not homogenous because of the layers. Each layer is considered homogenous because it is made of a single substance.
So cream or jam is not sponge. If it were homogenous it would be made of the same composition all the way up or through.

Cake B is not homogenous as before, but it is not unifrm either as the cream layer varies in thickness. So some slices will have more cream than others, even though they may be the same physical size.

OK so on the right I have expanded the scale of the layers.

Now I note that the jam is not homogenous because it is amde of large bits of fruit in a gel.

The sponge can still be considered homogenous at thiscscale because it is composed of the cake sponge material which contains lots of tiny holes or voids or bubbled where it has risen. However if we take a sensible sized small piece of this sponge each such piece will have the same average density of holes and cake.

However at the scale of an individual bubble the cake sponge material is no longer homogenous.

This echoes exchemist's comments which go down to an even finer level  - The atomic/ molecular level.

Hope this helps.

uniform1.thumb.jpg.794835cb0b35426844707ff200ffd9a8.jpg

 

 

 

Link to post
Share on other sites
7 minutes ago, studiot said:

Generally good stuff and a good addition/expansion of my offering, if a tad technical.  +1

However beware of the common statement that hydrogen bonds are weaker than 'normal' bonds. Some hydrogen bonds can be as strong or stronger, especially in organic chemistry.

 

 

 

 

 

That's interesting and I fully admit I am pretty rusty on a lot of this stuff. I had in mind as typical H bond strengths of the order of 5-10kcal/mol (showing my age). Can you give examples of much stronger ones? 

   

Link to post
Share on other sites
1 hour ago, exchemist said:

That's interesting and I fully admit I am pretty rusty on a lot of this stuff. I had in mind as typical H bond strengths of the order of 5-10kcal/mol (showing my age). Can you give examples of much stronger ones? 

   

I'm sure I've got some info in a book somewhere, I tried quickly to look it out but couldn't immediately see it.

I will try to dig it out for you.

Link to post
Share on other sites
Posted (edited)
8 hours ago, studiot said:

Generally good stuff and a good addition/expansion of my offering, if a tad technical.  +1

However beware of the common statement that hydrogen bonds are weaker than 'normal' bonds. Some hydrogen bonds can be as strong or stronger, especially in organic chemistry.

Glad it was of some help.

To further understand the difference between homogenous and uniform look at my diagrams of two standard sponge cakes.
A standard cake has a filling sandwiched between two slabs of sponge.

Cake A is uniform but not homogenous because of the layers. Each layer is considered homogenous because it is made of a single substance.
So cream or jam is not sponge. If it were homogenous it would be made of the same composition all the way up or through.

Cake B is not homogenous as before, but it is not unifrm either as the cream layer varies in thickness. So some slices will have more cream than others, even though they may be the same physical size.

OK so on the right I have expanded the scale of the layers.

Now I note that the jam is not homogenous because it is amde of large bits of fruit in a gel.

The sponge can still be considered homogenous at thiscscale because it is composed of the cake sponge material which contains lots of tiny holes or voids or bubbled where it has risen. However if we take a sensible sized small piece of this sponge each such piece will have the same average density of holes and cake.

However at the scale of an individual bubble the cake sponge material is no longer homogenous.

This echoes exchemist's comments which go down to an even finer level  - The atomic/ molecular level.

Hope this helps.

uniform1.thumb.jpg.794835cb0b35426844707ff200ffd9a8.jpg

 

 

 

Very well understood and thanks!

One of the reasons I placed a green shade in my grid with the x in the boxes " above 4th comment " was incase I needed to understand an individual molecule..

In this i mean, our homogenous " issue."

So with this new information, would this green shaded area vary in:

density? mass? electro static force? 

Since we are now dealing with molecules, I assume the entire grid "sponge cake" varies in the aforementioned not just the shaded area, is this correct?
 

 

 

 

 

Edited by OneWorldOneNumber
Link to post
Share on other sites
1 hour ago, OneWorldOneNumber said:

So with this new information, would this green shaded area vary in:

density?

Yes 

1 hour ago, OneWorldOneNumber said:

mass?

Yes

1 hour ago, OneWorldOneNumber said:

electro static force? 

Unknown, but likely yes. 

Link to post
Share on other sites
Posted (edited)
9 hours ago, iNow said:

Yes 

Yes

Unknown, but likely yes. 

Has there been any research to prove this scientifically and/or visually other than an electron microscope or another "way" to show that this is true?

Edited by OneWorldOneNumber
Link to post
Share on other sites

Perhaps there is research in this space. I'm not entirely sure, but that's not why I answered the way I did. Your questions have logical answers. Density will tend to vary (even if only slightly) between Volume A and Volume B. Likewise with mass... extract two equally sized volumes of clay and check their mass, you will see variance (due to the lack of purity in the samples). Similar with electrostatic force... will be pretty close and similar, but depends entirely on the sample(s) being measured. 

Link to post
Share on other sites
56 minutes ago, OneWorldOneNumber said:

Has there been any research to prove this scientifically and/or visually other than an electron microscope or another "way" to show that this is true?

Yes but you do not need an electron or any other microscope.

This question is very complicated, because it depends upon the scale you are working at, especially if you go down to the 'molecular' sizing.

I have been digging out some information both for you and for exchemist; I will post it in due course.

Remember also that some of the issues lie properly in the domain of soil mechanics as do their answers.

One point mentioned by exchemist is that the water holds the bulk clay together.
But then he says that creation of pottery dries out the clay.
So a good question is,

What then holds it together?

The answer is vitrification.

As a potter are you familiar with this idea ?

Link to post
Share on other sites
23 hours ago, exchemist said:

That's interesting and I fully admit I am pretty rusty on a lot of this stuff. I had in mind as typical H bond strengths of the order of 5-10kcal/mol (showing my age). Can you give examples of much stronger ones? 

   

OK so here is some more Chemistry which I hope will also be useful to Oneworld.

 

As I have mentioned before, homegeny depends upon the scale you are working at.

So starting inside the atom things are definitely not homogenous.
There is a massive nucleus surrounded by a lot of empty space containing some electrons.
Uniformity is represented by saying that every atom of a particular type is the same as every other atom of that type. For example all hydrogen atoms are the same.
(for those who know about isotopes I am ignoring them)

If we use those atoms to build molecules then again individual molecules are not homegenous since they are often made of different types of atoms. Even those that are combinations of atoms of the same type are not internally homogenous, in much the same way as atoms. So one hydrogen molecule looks much like another.

We represent molecules by the 'ball and stick' models shown in exchemist's post, where the balls are individual atoms and the sticks represent the forces that hold them together.

And yes, these forces are entirely electrical in origin.

16 hours ago, OneWorldOneNumber said:

Very well understood and thanks!

One of the reasons I placed a green shade in my grid with the x in the boxes " above 4th comment " was incase I needed to understand an individual molecule..

In this i mean, our homogenous " issue."

So with this new information, would this green shaded area vary in:

density? mass? electro static force? 

Since we are now dealing with molecules, I assume the entire grid "sponge cake" varies in the aforementioned not just the shaded area, is this correct?

For small molecules again all molecules are essentially the same as with atoms and of definite composition, for example methane, ethane propane etc. Individual molecules can be isolated and, in principle at least, you could hand me one molecule of methane.
So a large aggregate (number) of them is homogenous in that there would be the same number per cubic centimetre for each cc on your grid.
Note that we live in a 3D world so we really need to work in terms of volume not area.
This is why I talk of 'bulk clay'.

However clays are in a different category.
That of super large molecules.
Super large molecules happen when a non specific number of atoms join together, unlike methane which always has 4 hydrogens joined to one carbon.
A diamond crystal is an example of this.
You could not, even in principle, hand me one 'molecule' of diamond. Another example would be a common salt crystal.

Clays are like this only their structure is vastly more complex.

But they all still can be represented by balls and sticks.

As regards the sticks or (chemical) bonds there are several types available.
The strength of these bonds are usually measured not in force units but in the energy needed to break them.
Here is a table

clay1.jpg.52b1151c0450c32a93ed16204f88c124.jpg

 

Now my table lists intramolecular bonds, which hold the atoms together in simple molecules

and intermolecular bonds which can bind simple molecules such as water to each other hydrogen bonds.

And yes the internal bonds in a single simple molecule are stronger than a single hydrogen bond, in general.

But in large molecules there can be many many hydrogen bonds holding the parts together.

For example in DNA the two strands or chains are held together by literally hundreds of hydrogen bonds this is called 'cross linking'

Clays come in sheets rather than thin strands so the effect is even more marked.

The subject is of such importance that books such as these have been written just about these clay minerals.

clay2.jpg.4507ed07f45b5aa8500d677081ae42dd.jpg

 

 

Now to return to my original contention.

For pottery the scale Chemistry works at is too fine and we should step up into the realms of mechanical properties.

Here the clay may be considered homogenous for Pottery purposes since it will have come from a relatively thin piece of clay.
I say this because geolically clay may have been laid down in very thick beds, up to thousands of metres thick.
When this happns the clay may be stratified because as the particles which form it settle out of the water the larger, heavier ones settle first so will be at the bottom of any strata which mark the start and finish of a period of formation.
But pottery type clays will be dug out within a couple of metre depths so will be homogenous.

 

Next post we can examine the mechanical properties that demonstrate this question of homogeny and uniformity.

You may have heard of the Atterberg Limits for field testing clays.

Link to post
Share on other sites
12 hours ago, studiot said:

OK so here is some more Chemistry which I hope will also be useful to Oneworld.

 

As I have mentioned before, homegeny depends upon the scale you are working at.

So starting inside the atom things are definitely not homogenous.
There is a massive nucleus surrounded by a lot of empty space containing some electrons.
Uniformity is represented by saying that every atom of a particular type is the same as every other atom of that type. For example all hydrogen atoms are the same.
(for those who know about isotopes I am ignoring them)

If we use those atoms to build molecules then again individual molecules are not homegenous since they are often made of different types of atoms. Even those that are combinations of atoms of the same type are not internally homogenous, in much the same way as atoms. So one hydrogen molecule looks much like another.

We represent molecules by the 'ball and stick' models shown in exchemist's post, where the balls are individual atoms and the sticks represent the forces that hold them together.

And yes, these forces are entirely electrical in origin.

For small molecules again all molecules are essentially the same as with atoms and of definite composition, for example methane, ethane propane etc. Individual molecules can be isolated and, in principle at least, you could hand me one molecule of methane.
So a large aggregate (number) of them is homogenous in that there would be the same number per cubic centimetre for each cc on your grid.
Note that we live in a 3D world so we really need to work in terms of volume not area.
This is why I talk of 'bulk clay'.

However clays are in a different category.
That of super large molecules.
Super large molecules happen when a non specific number of atoms join together, unlike methane which always has 4 hydrogens joined to one carbon.
A diamond crystal is an example of this.
You could not, even in principle, hand me one 'molecule' of diamond. Another example would be a common salt crystal.

Clays are like this only their structure is vastly more complex.

But they all still can be represented by balls and sticks.

As regards the sticks or (chemical) bonds there are several types available.
The strength of these bonds are usually measured not in force units but in the energy needed to break them.
Here is a table

clay1.jpg.52b1151c0450c32a93ed16204f88c124.jpg

 

Now my table lists intramolecular bonds, which hold the atoms together in simple molecules

and intermolecular bonds which can bind simple molecules such as water to each other hydrogen bonds.

And yes the internal bonds in a single simple molecule are stronger than a single hydrogen bond, in general.

But in large molecules there can be many many hydrogen bonds holding the parts together.

For example in DNA the two strands or chains are held together by literally hundreds of hydrogen bonds this is called 'cross linking'

Clays come in sheets rather than thin strands so the effect is even more marked.

The subject is of such importance that books such as these have been written just about these clay minerals.

clay2.jpg.4507ed07f45b5aa8500d677081ae42dd.jpg

 

 

Now to return to my original contention.

For pottery the scale Chemistry works at is too fine and we should step up into the realms of mechanical properties.

Here the clay may be considered homogenous for Pottery purposes since it will have come from a relatively thin piece of clay.
I say this because geolically clay may have been laid down in very thick beds, up to thousands of metres thick.
When this happns the clay may be stratified because as the particles which form it settle out of the water the larger, heavier ones settle first so will be at the bottom of any strata which mark the start and finish of a period of formation.
But pottery type clays will be dug out within a couple of metre depths so will be homogenous.

 

Next post we can examine the mechanical properties that demonstrate this question of homogeny and uniformity.

You may have heard of the Atterberg Limits for field testing clays.

That table seems to agree with my understanding of the strength of H bonds, i.e. up to ~ 10kcal/mol or so.  

Did you ever find the organic chemistry example you were talking about, of a much stronger one? 

Link to post
Share on other sites
Posted (edited)
23 hours ago, studiot said:

OK so here is some more Chemistry which I hope will also be useful to Oneworld.

 

As I have mentioned before, homegeny depends upon the scale you are working at.

So starting inside the atom things are definitely not homogenous.
There is a massive nucleus surrounded by a lot of empty space containing some electrons.
Uniformity is represented by saying that every atom of a particular type is the same as every other atom of that type. For example all hydrogen atoms are the same.
(for those who know about isotopes I am ignoring them)

If we use those atoms to build molecules then again individual molecules are not homegenous since they are often made of different types of atoms. Even those that are combinations of atoms of the same type are not internally homogenous, in much the same way as atoms. So one hydrogen molecule looks much like another.

We represent molecules by the 'ball and stick' models shown in exchemist's post, where the balls are individual atoms and the sticks represent the forces that hold them together.

And yes, these forces are entirely electrical in origin.

For small molecules again all molecules are essentially the same as with atoms and of definite composition, for example methane, ethane propane etc. Individual molecules can be isolated and, in principle at least, you could hand me one molecule of methane.
So a large aggregate (number) of them is homogenous in that there would be the same number per cubic centimetre for each cc on your grid.
Note that we live in a 3D world so we really need to work in terms of volume not area.
This is why I talk of 'bulk clay'.

However clays are in a different category.
That of super large molecules.
Super large molecules happen when a non specific number of atoms join together, unlike methane which always has 4 hydrogens joined to one carbon.
A diamond crystal is an example of this.
You could not, even in principle, hand me one 'molecule' of diamond. Another example would be a common salt crystal.

Clays are like this only their structure is vastly more complex.

But they all still can be represented by balls and sticks.

As regards the sticks or (chemical) bonds there are several types available.
The strength of these bonds are usually measured not in force units but in the energy needed to break them.
Here is a table

clay1.jpg.52b1151c0450c32a93ed16204f88c124.jpg

 

Now my table lists intramolecular bonds, which hold the atoms together in simple molecules

and intermolecular bonds which can bind simple molecules such as water to each other hydrogen bonds.

And yes the internal bonds in a single simple molecule are stronger than a single hydrogen bond, in general.

But in large molecules there can be many many hydrogen bonds holding the parts together.

For example in DNA the two strands or chains are held together by literally hundreds of hydrogen bonds this is called 'cross linking'

Clays come in sheets rather than thin strands so the effect is even more marked.

The subject is of such importance that books such as these have been written just about these clay minerals.

clay2.jpg.4507ed07f45b5aa8500d677081ae42dd.jpg

 

 

Now to return to my original contention.

For pottery the scale Chemistry works at is too fine and we should step up into the realms of mechanical properties.

Here the clay may be considered homogenous for Pottery purposes since it will have come from a relatively thin piece of clay.
I say this because geolically clay may have been laid down in very thick beds, up to thousands of metres thick.
When this happns the clay may be stratified because as the particles which form it settle out of the water the larger, heavier ones settle first so will be at the bottom of any strata which mark the start and finish of a period of formation.
But pottery type clays will be dug out within a couple of metre depths so will be homogenous.

 

Next post we can examine the mechanical properties that demonstrate this question of homogeny and uniformity.

You may have heard of the Atterberg Limits for field testing clays.

I see mineralogy books are quite expensive but worth paying for considering the rich information they contain.. Id personally invest in this field 1st before tackling on physics.

You stated: Note that we live in a 3D world so we really need to work in terms of volume not area.

 

This came to mind:

About " volume 3d, and cubic centi-meters or "units these represent." for my grid example " 4th comment" with the green shaded area that represents non-homogenous location.... Some further insight...

When you say, 3d as volume, do we "still consider this "a complete body of mass?" isn't this the same as our homogenous issue?

 

Should it be "individual 3d Volumes<--- as plural?

 

I'm thinking ""intermolecular forces??""" but i'm not too sure now because of the homogenous issue.

 

Another notion, what would these masses be relative to? Earth's gravitational attraction is rather weak i've read.


 

Edited by OneWorldOneNumber
Link to post
Share on other sites
On 4/6/2021 at 10:32 AM, exchemist said:

That table seems to agree with my understanding of the strength of H bonds, i.e. up to ~ 10kcal/mol or so.  

Did you ever find the organic chemistry example you were talking about, of a much stronger one? 

I would like to defer discussion of hydrogen bonding to another thread as it is taking us further and further off topic.

The weakest standard bond my copy of Lange's Chemistry Handbook lists is the lithium - Lithium bond at 11 kcal/mol

and the strongest hydrogen bond this modern article lists is the formic acid - flouride ion one at 48 kcal/mol (on page 22)

https://www.tdx.cat/bitstream/handle/10803/7945/tdhg.pdf?sequence=3Girona

But the important point I wanted to make was not the strength if the individual bond but the collective strength of many bonds applied to large molecular aggregates.

 

23 hours ago, OneWorldOneNumber said:

I see mineralogy books are quite expensive but worth paying for considering the rich information they contain.. Id personally invest in this field 1st before tackling on physics.

You stated: Note that we live in a 3D world so we really need to work in terms of volume not area.

 

This came to mind:

About " volume 3d, and cubic centi-meters or "units these represent." for my grid example " 4th comment" with the green shaded area that represents non-homogenous location.... Some further insight...

When you say, 3d as volume, do we "still consider this "a complete body of mass?" isn't this the same as our homogenous issue?

 

Should it be "individual 3d Volumes<--- as plural?

 

I'm thinking ""intermolecular forces??""" but i'm not too sure now because of the homogenous issue.

 

Another notion, what would these masses be relative to? Earth's gravitational attraction is rather weak i've read.


 

Yes, most Science texts are expensive, especially working ones.

 

To continue with the mechanical aspect here is some data to review.
Don't worry about the forumale, just look at the daigrams and the text and get an idea of how any soil material is made up and behaves as it does mechanically.
This will help enormously when we look particularly at clays.

soils1.thumb.jpg.fb3e9602b4862587452bd256a89bb689.jpg

soils2.thumb.jpg.1e4178d1dd73ba105bf1d4e9c5111299.jpg

 

I have mentioned the Atterberg limits, but you did not answer my question or the one about vitrification so here are a couple of photos of how geologists and soils engineers test soild for plasticity.

 

soils3.jpg.e08fa5220aaed389716fcb9fa0ee369d.jpg

 

I'm sorry I don't have any more time tonight but will come back to it.

So here is a website that explains clay from potter's viewpoint , including the subject of my other question - vitrification.

https://thepotterywheel.com/types-of-clay-for-pottery/

 

soils4.jpg

Edited by studiot
Link to post
Share on other sites
35 minutes ago, studiot said:

I would like to defer discussion of hydrogen bonding to another thread as it is taking us further and further off topic.

The weakest standard bond my copy of Lange's Chemistry Handbook lists is the lithium - Lithium bond at 11 kcal/mol

and the strongest hydrogen bond this modern article lists is the formic acid - flouride ion one at 48 kcal/mol (on page 22)

https://www.tdx.cat/bitstream/handle/10803/7945/tdhg.pdf?sequence=3Girona

But the important point I wanted to make was not the strength if the individual bond but the collective strength of many bonds applied to large molecular aggregates.

 

Yes, most Science texts are expensive, especially working ones.

 

To continue with the mechanical aspect here is some data to review.
Don't worry about the forumale, just look at the daigrams and the text and get an idea of how any soil material is made up and behaves as it does mechanically.
This will help enormously when we look particularly at clays.

soils1.thumb.jpg.fb3e9602b4862587452bd256a89bb689.jpg

soils2.thumb.jpg.1e4178d1dd73ba105bf1d4e9c5111299.jpg

 

I have mentioned the Atterberg limits, but you did not answer my question or the one about vitrification so here are a couple of photos of how geologists and soils engineers test soild for plasticity.

 

soils3.jpg.e08fa5220aaed389716fcb9fa0ee369d.jpg

 

I'm sorry I don't have any more time tonight but will come back to it.

So here is a website that explains clay from potter's viewpoint , including the subject of my other question - vitrification.

https://thepotterywheel.com/types-of-clay-for-pottery/

 

soils4.jpg

Thanks for the link to the paper, which satisfies my curiosity. Agree we should not pursue the topic of H bonds further here, interesting though I find it. 

Link to post
Share on other sites
Posted (edited)
On 4/7/2021 at 12:55 PM, studiot said:

I would like to defer discussion of hydrogen bonding to another thread as it is taking us further and further off topic.

The weakest standard bond my copy of Lange's Chemistry Handbook lists is the lithium - Lithium bond at 11 kcal/mol

and the strongest hydrogen bond this modern article lists is the formic acid - flouride ion one at 48 kcal/mol (on page 22)

https://www.tdx.cat/bitstream/handle/10803/7945/tdhg.pdf?sequence=3Girona

But the important point I wanted to make was not the strength if the individual bond but the collective strength of many bonds applied to large molecular aggregates.

 

Yes, most Science texts are expensive, especially working ones.

 

To continue with the mechanical aspect here is some data to review.
Don't worry about the forumale, just look at the daigrams and the text and get an idea of how any soil material is made up and behaves as it does mechanically.
This will help enormously when we look particularly at clays.

soils1.thumb.jpg.fb3e9602b4862587452bd256a89bb689.jpg

soils2.thumb.jpg.1e4178d1dd73ba105bf1d4e9c5111299.jpg

 

I have mentioned the Atterberg limits, but you did not answer my question or the one about vitrification so here are a couple of photos of how geologists and soils engineers test soild for plasticity.

 

soils3.jpg.e08fa5220aaed389716fcb9fa0ee369d.jpg

 

I'm sorry I don't have any more time tonight but will come back to it.

So here is a website that explains clay from potter's viewpoint , including the subject of my other question - vitrification.

https://thepotterywheel.com/types-of-clay-for-pottery/

 

soils4.jpg

From what I gather " from the 2 book images", it seems that water " is used as a base" to understand the "bonding" of soil or its mass relationship to force?

So force I assume is homogenous at any scale???

Another notion, i see a gradient too, meaning from large thick pieces of soil, to less thick to less thick, until the most finest pieces of soil are found at the top...

In other words from dense to less dense and least dense...

I will further research the links provided, I want to fully understand this...

 

Great information!

 

On 4/5/2021 at 8:29 AM, iNow said:

Perhaps there is research in this space. I'm not entirely sure, but that's not why I answered the way I did. Your questions have logical answers. Density will tend to vary (even if only slightly) between Volume A and Volume B. Likewise with mass... extract two equally sized volumes of clay and check their mass, you will see variance (due to the lack of purity in the samples). Similar with electrostatic force... will be pretty close and similar, but depends entirely on the sample(s) being measured. 

Thanks for making the logic more clear, it makes 100% sense!

 

I can't help but to ask, please correct me if i'm wrong.

Because of the "scale factor" ie, our accuracy "homogenous issue" at molecular levels, dealing with electrostatic forces from micro to macro, can we " assume" forces in general are homogenous?

Just as our methane molecule example you can hand out one molecule of methane, I assume you can do the same with force, because shouldn't force be "logical?"

Shouldn't force be an observation at any scale???

Edited by OneWorldOneNumber
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.