Jump to content

Melting Wood?


Gness

Recommended Posts

i was curious if anyone had any input on weather or not melting wood would be plausable in conditions where there wasnt any oxygen, some people belive it would turn to charcoal, but i belive it would very well melt considering, you need 3 main things to have a fire. fuel oxygen and a source of ignition, take away one and it should not ignite into flames therefore at a certain tempature, it would melt.

Link to comment
Share on other sites

Under mild conditions (200-300 °C) and relatively long reaction times, you get mostly charcoal.

At higher temperatures (400-600 °C) and quite short reaction times, you get a liquid, called pyrolysis oil. It's quite different from melting wood though... it involves many (many!) reactions.

At even higher temperatures (> 700°C) you get mostly gas. The process is then called gasification.

 

When we talk about melting something, it means we can also do the reverse: we can also freeze it again, and it will be the same solid as before.

With none of the processes that I described above will we ever get our wood back. There is no reverse... so it is not 'melting'.

Link to comment
Share on other sites

Under almost any conditions above about 200 C you will eventually get mainly charcoal and water. At high enough temperatures the steam and charcoal will react to give carbon monoxide and hydrogen.

What you cannot get is "molten wood".

Link to comment
Share on other sites

  • 2 weeks later...

Under almost any conditions above about 200 C you will eventually get mainly charcoal and water. At high enough temperatures the steam and charcoal will react to give carbon monoxide and hydrogen.

What you cannot get is "molten wood".

 

What if you put a block of wood under a very strong hydraulic press. Then operate the press so that it squeezes down on the wood.

 

All the water in the wood will get squeezed out. This squeezed-out water will probably still have wood chemicals in it. So it can be fairly be called "liquid" wood.

 

And isn't "liquid" the same as "molten". So this "liquid" wood can justly be termed "molten" wood.

Link to comment
Share on other sites

What if you put a block of wood under a very strong hydraulic press. Then operate the press so that it squeezes down on the wood.

 

All the water in the wood will get squeezed out. This squeezed-out water will probably still have wood chemicals in it. So it can be fairly be called "liquid" wood.

 

And isn't "liquid" the same as "molten". So this "liquid" wood can justly be termed "molten" wood.

 

so juicing an orange is actually melting an orange?

 

the OP is talking about melting wood.

 

the liquid you are reffering to wouldn't be wood in any way, you'd have some of the components of wood, but not all of them and definitely not in the right composition. it would not be liquid wood.

Link to comment
Share on other sites

so juicing an orange is actually melting an orange?

 

the OP is talking about melting wood.

 

the liquid you are reffering to wouldn't be wood in any way, you'd have some of the components of wood, but not all of them and definitely not in the right composition. it would not be liquid wood.

 

 

But isn't a melted substance exactly the same as a liquid substance? Just at a higher temperature.

 

Eg, Ice at a higher temperature, is liquid water - or in other words, melted ice.

Link to comment
Share on other sites

What if you put a block of wood under a very strong hydraulic press. Then operate the press so that it squeezes down on the wood.

 

All the water in the wood will get squeezed out. This squeezed-out water will probably still have wood chemicals in it. So it can be fairly be called "liquid" wood.

 

And isn't "liquid" the same as "molten". So this "liquid" wood can justly be termed "molten" wood.

 

This top[ic is listed under "Other Sciences". I understand the applicability of "Other". Might someone explain the relevance of word # 2 ?

Link to comment
Share on other sites

But isn't a melted substance exactly the same as a liquid substance? Just at a higher temperature.

 

Eg, Ice at a higher temperature, is liquid water - or in other words, melted ice.

If you freeze water, you get ice. And if you melt ice, you get water. This is a reversible process.

 

If you squeeze water out of wood, you cannot take that water, and turn it back into wood by changing the temperature. You probably get a very dirty ice instead...

Link to comment
Share on other sites

not to mention the water out of wood is not liquid wood. its 'extract of wood' but its not wood itself.

 

if i take the oil out of a car is it a liquid car?

 

I really doubt you'd get people to go a long with that because it doesn't make sense.

Link to comment
Share on other sites

not to mention the water out of wood is not liquid wood. its 'extract of wood' but its not wood itself.

 

if i take the oil out of a car is it a liquid car?

 

I really doubt you'd get people to go a long with that because it doesn't make sense.

 

Point accepted. The oil from the car, obviously wouldn't be "liquid car". As the water from the wood, wouldn't really be "liquid wood".

 

And if an entire car were melted - with all its metal, glass, rubber and plastic components. This would produce a witches' brew of boiling, liquid gunge. Which would be "melted car", undeniably.

 

But I now understand from CaptainPanic's replies, that it wouldn't be "liquid car" - because its "car-ness", ie its vehicular, automotive nature, would have been irreversibly destroyed.

Edited by Dekan
Link to comment
Share on other sites

  • 2 weeks later...

 

When we talk about melting something, it means we can also do the reverse: we can also freeze it again, and it will be the same solid as before.

 

 

 

To suppose melting something can only happen if you can make it fuse afterwards is wrong . I have melted enough steel to know that is a fact . When the steel melted it was melted . When it fused afterwards this did not suddenly validate the melting .

Edited by Hal.
Link to comment
Share on other sites

With reference to the original question of whether a piece of wood can be melted or not , it does not have to be shown that the process is reversible so that fusion then becomes a precondition for melting .

 

If a piece of ice is heated to 10 degrees celsius under normal atmospheric pressure it will be liquid water and termed melted . It does not have to be shown that it is possible for it to be frozen to show it has been melted , it does not have to be frozen to show it has been melted .

Link to comment
Share on other sites

It does not have to be shown that it is possible for it to be frozen to show it has been melted , it does not have to be frozen to show it has been melted .

 

Technically that is true, but the definition of the words "freeze" and "melt" contains the concept of reversibility (on a thermodynamic level). If the OP is asking about melting wood, the point should be to explain the difference between melting and decomposition; how decomposition is not reversible, and so more correctly applies to wood... in this case.

 

During the decomposition of wood, many chemicals are generated that can melt and freeze (or decompose further); but the "wood" is not melting, right?

 

~ :)

 

 

p.s.op: Please search and study pyrolysis... to see an amazing world... in the chemistry of wood decomposition... pyrolignous acid... pyrenes and pyranones!

Edited by Essay
Link to comment
Share on other sites

With reference to the original question of whether a piece of wood can be melted or not , it does not have to be shown that the process is reversible so that fusion then becomes a precondition for melting .

 

If a piece of ice is heated to 10 degrees celsius under normal atmospheric pressure it will be liquid water and termed melted . It does not have to be shown that it is possible for it to be frozen to show it has been melted , it does not have to be frozen to show it has been melted .

 

if the ice 'melts' and is suddenly no longer composed of H2O molecules then it wouldn't be melting as there is a reaction involved that is more than just a few intermolecular bonds.

 

this is what happens with wood. you can get it to change phase but in the process you are destroying chemicals and turning them into other chemicals so it is not just a phase change and hence, not melting.

 

my usage of the refreezing was meant to show that it must still be the same stuff in both the liquid and solid to be called melting as phase changes do not involve chemical changes, only structural.

 

Lets take sodium bicarbonate, if you heat this you can end up with a liquid (if you do it slowly then you won't even notice the gas being given off) and then if you allow it to cool you'll end up with a similar looking solid. however if you pick it up you'll get caustic burns as its now sodium oxide which will dissolve to form sodium hydroxide. so it wasn't just melting. there was a decomposition reaction along the way and you can't get the sodium carbonate back without further reactions.

 

so you get where we are coming from now?

Link to comment
Share on other sites

Essay , you are saying all things are there for all people and they aren't .

 

If you define melting and freezing to include either the possibility or actual accomplishment of reversibility , then judging my usage of these terms using your definitions say I'm wrong . Don't say that technically I am correct and you are also correct when your meanings are not the same as mine . I don't believe reversibility is a requirement either for melting or for fusion .

 

insane_alien ,

 

Let's not confuse the fact that my argument is of the requirements to show something has been melted and not whether it is possible to melt wood .

Edited by Hal.
Link to comment
Share on other sites

wood doesn't really factor in to it.

 

phase changes are reversible processes that can be performed by the addition/subtraction of thermal energy and/or pressure.

 

if said process is not reversible under addition/subtraction of thermal energy and/or pressure then it is not a phase change, it is a reaction.

 

the reaction may result in products of a different phase but it is not that the original substance has changed phase it is that original substance is not there but a different substance in a different phase has replaced it.

 

think of burning some petrol

 

you haven't turned the petrol into gaseous petroleum(evapouration), you've turned the petrol into CO2 and water vapour. its not a phase change but a reaction.

Link to comment
Share on other sites

Sorry, but this is a bit confusing.

"Lets take sodium bicarbonate, if you heat this you can end up with a liquid (if you do it slowly then you won't even notice the gas being given off) and then if you allow it to cool you'll end up with a similar looking solid. however if you pick it up you'll get caustic burns as its now sodium oxide which will dissolve to form sodium hydroxide."

 

Sodium bicarbonate doesn't melt, it decomposes to steam, CO2 and sodium carbonate.

 

Sodium carbonate is, for all practical purposes, stable to heat. It will melt at about 850 C

 

It won't decompose to sodium oxide under any sensible conditions, but it will boil at about 1600C

 

I think a better example would be sugar. If you heat it it sort of melts, but even before it does so it turns brown. That colour change is a chemical reaction. If you cool it down again, it doesn't turn white.

Link to comment
Share on other sites

With reference to the original question of whether a piece of wood can be melted or not , it does not have to be shown that the process is reversible so that fusion then becomes a precondition for melting .

 

If a piece of ice is heated to 10 degrees celsius under normal atmospheric pressure it will be liquid water and termed melted . It does not have to be shown that it is possible for it to be frozen to show it has been melted , it does not have to be frozen to show it has been melted .

In fact, it does. Although for water/ice we can accept that it melts/freezes because we're completely familiar with water so it would be a bit unnecessary to prove it every time again.

 

However, if you want to construct a phase diagram (and freezing and melting is all about phase diagrams) then it is vitally important that you show that it is a reversible process. A material may not have been in its equilibrium. Some materials have multiple solid forms. For example, water has at least 15 different forms of ice (where individual molecules are arranged differently). And some decompose when you heat them (like wood).

Link to comment
Share on other sites

It was this point you made, which was so specifically constrained, that was easily granted as true; regardless of whether my broad definition (the point about reversibility) was true or not.

Let's not confuse the fact that my argument is of the requirements to show something has been melted and not whether it is possible to melt wood .

But....

 

Hey, you're right! I don't find reversibility mentioned in the dictionary definition.

 

As a chemist, I just assumed.... ;)

But I suppose I was thinking about the "melting point" of pure substances, which does demonstrate reversibility (and so that would not apply to wood).

 

And in fact the dictionary even mentioned "disintegration," as well as sugar melting in the mouth, mist melted by the morning sun, etc.

 

Thanks; I learned something! :)

~

 

p.s. You sometimes use "fusion" instead of "freezing" in your posts, or am I assuming something again? Were you instead discussing different kinds of melting?

Link to comment
Share on other sites

And in fact the dictionary even mentioned "disintegration," as well as sugar melting in the mouth, mist melted by the morning sun, etc.

Using dictionary definitions for scientific things can be quite misleading. Sugar dissolves in your mouth. In fact, sugar is one of those components that decomposes before it melts. It has no melting point.

 

So, in short, the dictionary is wrong from a chemical point of view. But the dictionary doesn't care. The dictionary describes the language... and language has a lot of sayings that are wrong from a scientific point of view. In language, weight and mass are considered synonyms (in science, they're not). In language, you can suck something up, (in science, it's the pressure gradient that causes movement). In language, the sun rises (in science, the earth rotates).

 

This is a science forum. So, sugar does not melt in your mouth. And the mist evaporates in the morning sun.

Link to comment
Share on other sites

Essay ,

 

I've seen that people on the internet are using fusion to mean melting and here is why I think this is so . When it is talked of that an object melts a value for heat that is applied to the situation is the heat of fusion ( the reverse , be careful with the signs ) . From always looking for values that refer to melting they are always looking for the term fusion . This has led to people thinking fusion is a word for melting . In a similiar way the heat of evaporation is being applied to condensation . Let's hope people don't try to call evaporation and condensation the same thing .

 

Fusion when I use the term means to me solidification , freezing , crystallization .

 

CaptainPanic ,

 

we differ in opinion because you're melting has been defined as reversible . I , and it is only I I speak of , see no problem in using a definition of melting that is reversible or irreversible , thus it can then be independent of any proof that the object can be refrozen . So , if a person is trying to prove that a piece of wood can be melted , with my definition , they don't have to prove that the piece of wood can be fused in a reverse process .

Link to comment
Share on other sites

CaptainPanic ,

 

we differ in opinion because you're melting has been defined as reversible . I , and it is only I I speak of , see no problem in using a definition of melting that is reversible or irreversible , thus it can then be independent of any proof that the object can be refrozen . So , if a person is trying to prove that a piece of wood can be melted , with my definition , they don't have to prove that the piece of wood can be fused in a reverse process .

Yes, but the question was not whether in your opinion, wood can melt. The OP did not ask "Hal., do you think that according to your personal definition wood can melt?".

 

The question was asked on a science forum whether according to science, wood can melt.

 

And that's not an opinion. And it can't. Because although it turns to a liquid, it also decomposes and cannot reversibly be turned back into wood (and partially also because it also forms a solid, and also some gas).

Link to comment
Share on other sites

we differ in opinion because you're melting has been defined as reversible . I , and it is only I I speak of , see no problem in using a definition of melting that is reversible or irreversible ,

That is interesting. Do you really see no problem in using a definition that is different from that used by all other informed people? I find that a bizarre position to adopt, but am willing to be convinced that is a postion that has merit. Over to you.

Link to comment
Share on other sites

 

Would the definition I speak of radically change any current instance of accepted melting ? , no , it would include it . It is a slight extension , a step , probably nothing new that may/may not have been used in the past , which would encourage those who think they can melt something not to worry about fusion .

 

 

 

 

Link to comment
Share on other sites

Guest
This topic is now closed to further replies.
×
×
  • 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.