Can a pencil be put back together

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SUMMARY

The discussion centers on the inability to reassemble a broken pencil, focusing on the atomic and molecular interactions involved. Participants assert that the bonds between carbon and graphite atoms must be re-established, which requires overcoming an energy barrier. The conversation highlights that while the pencil's chemical properties remain unchanged, the physical separation leads to oxidation of exposed surfaces, complicating reassembly. The consensus is that without a catalyst or sufficient energy input, the pencil cannot return to its original form.

PREREQUISITES
  • Understanding of atomic and molecular bonding, specifically covalent and ionic bonds.
  • Knowledge of energy barriers in chemical reactions and the concept of activation energy.
  • Familiarity with oxidation processes and their implications on material properties.
  • Basic principles of physical versus chemical changes in matter.
NEXT STEPS
  • Research the concept of activation energy in chemical reactions.
  • Study the oxidation process and its effects on materials, particularly carbon-based compounds.
  • Explore the differences between solid and liquid bonding, especially in metals.
  • Investigate the role of intermolecular forces in the reassembly of materials.
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Students and professionals in chemistry, materials science, and physics who are interested in the fundamental principles of bonding and material properties, as well as anyone curious about the physical changes in everyday objects.

  • #31
Remember the definitions of liquids and solids. A liquid is a substance that has a definite volume, but where the molucules creating the substance are able to move over each other freely. In a solid, the molecules are stuck in position compared to their surrounding molecules and are unable to move freely. The forces that make a molecule "stuck" or "unstuck" compared to those around it are attractive intermolecular forces.

So to answer your question simply: there are no strong attractive intermolecular forces in liquids, because if there were, it would be a solid.

~Lyuokdea
 
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  • #32
thanks lyuokdea!
 
  • #33
Lyuokdea said:
Remember the definitions of liquids and solids. A liquid is a substance that has a definite volume, but where the molucules creating the substance are able to move over each other freely. In a solid, the molecules are stuck in position compared to their surrounding molecules and are unable to move freely. The forces that make a molecule "stuck" or "unstuck" compared to those around it are attractive intermolecular forces.

So to answer your question simply: there are no strong attractive intermolecular forces in liquids, because if there were, it would be a solid.

~Lyuokdea
But there are significant intermolecular forces in a liquid - otherwise it would be a gas. And the forces that make a solid a solid are attractive rather than repulsive at long distances. It still doesn't make sense to me. Thank you for trying, by the way.
 
  • #34
A liquid has 2 free spaces to move, due to no strong intermolecular forces, it has intermolecular forces but they are weak
A solid has only 1 free space correct? keeping it a solid. it has strong intermolecular forces, keeping it together.. think of the force as a vacuum, making everything as compact as it can get with the giving molcules.

aka what lyuo said.
 
  • #35
Zygotic Embryo said:
A liquid has 2 free spaces to move, due to no strong intermolecular forces, it has intermolecular forces but they are weak
A solid has only 1 free space correct? keeping it a solid. it has strong intermolecular forces, keeping it together.. think of the force as a vacuum, making everything as compact as it can get with the giving molcules.

aka what lyuo said.
Yes, a solid has strong intermolecular forces, but they are attractive intermolecular forces. Where do the extra repulsive forces come from, if that is in fact the cause?
 
  • #36
I don't understand the confusion, is the following correct?
Code: 
The pencil cannot be put back together because atomic bonds have broken and it
would require extra energy to reform them.
And where does the energy come from if we needed to?
 
  • #37
Zygotic Embryo said:
A friend of mine was asking the teacher, why can't a pencil ( or any object for that matter) just simply..be put together if it's snapped in half. Are bonds broken, what's going on here? What's causing me from connecting the two pieces back together back to its original form without a catalyst such a glue... This question is on the atomic or subatomic level, peers where saying " because the wood and graphite is separated" that's true in a sence, but i want to go atomic.

I think that, when we stick things, it works basically due to the molecular attraction (bonds, etc) between the two surfaces.

For example, when we use glue, the molecular attraction between the surface of the glue and the surfaces of the material to which it is applied makes it stick.

Also, once we bring the two surfaces very close to each other (ie, angstroms), the two surfaces should adhere. For example, let's say you have 2 broken parts of the same material (part A & part B). Now the inter molecular distances in each part are generally the order of a few angstroms. So, if we bring the two surfaces this close, there won't be any distinction between the two parts and it should rejoin into one continuous part. I think the reason we can't stick the broken surfaces normally by contact alone is because of dirt and the dust in air.

In fact, I remember reading somewhere that mica, after being cut, can be rejoined by contact alone if it isn't exposed to impurities.
 
Last edited:
  • #38
Mk said:
I don't understand the confusion, is the following correct?
Code: 
The pencil cannot be put back together because atomic bonds have broken and it
would require extra energy to reform them.
And where does the energy come from if we needed to?
Well, we can't provide the right kind of energy, which is why it can't be done this way. Providing heat (giving the molecules a boost of kinetic energy) would work theoretically, but it's way too random and would do more damage than good.

It would be like trying to re-stack a set of toy blocks by using a blowtorch to move them around.

How DO you re-stack a set of toy blocks? Subtlely, i.e. by hand. How do you reassemble wood? Only a living plant can make wood.
 
  • #39
Zygotic Embryo said:
A friend of mine was asking the teacher, why can't a pencil ( or any object for that matter) just simply..be put together if it's snapped in half. Are bonds broken, what's going on here? What's causing me from connecting the two pieces back together back to its original form without a catalyst such a glue... This question is on the atomic or subatomic level, peers where saying " because the wood and graphite is separated" that's true in a sence, but i want to go atomic.
Is there a reason why you decided to ask this in the GD forum ?
 

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