And would it be possible to melt wood into a puddle in the right conditions?
In: Chemistry
Also I dont think you could ever melt wood because it’s carbon based which likes to bond to Hydrogen and Oxygen, both like to combust.
When wood heats up it releases gasses that ignite because its natural. When all the gas is used up it turns to ash.
When metal heats up it doesn’t particularly release any molecules, the bonds between each of the metal atoms gets weaker so they can move and slide over each other, making it liquid.
Because metal can be heated to its liquid transition temperature without combusting.
Combustion is an oxidation reaction, meaning oxygen has to attack the molecules of the fuel to burn. Wood and other fuels like gasoline are very easy to oxidize if you give them heat.
Metal isn’t like that. Metallic bonds are some of the strongest in nature. That means oxygen has a very difficult time pulling those molecules apart to burn them because they’re packed so close together.
That’s not to say you can’t burn metal- if it’s powdered it often becomes not only flammable but explosive. That’s because there’s a lot more surface area for oxygen to get in and attack those molecules.
The problem with trying to melt wood is that you have to heat it up a lot. When you heat wood that much, it goes through a chemical reaction (burning) long before it melts and stops being wood in the process.
The other problem is that unlike typical metals, wood is composed of a mix of very different materials. It has water, organic molecules, inorganic molecules, etc in it, totaling hundreds of types of chemical. Mixed materials like that don’t have the same kind of clean melting/boiling point that pure materials do.
TL;DR the closest you will get to melted wood is oil and natural gas.
A few things.
Melting is temperature and pressure dependant. (Phase diagram)
I’ll talk about carbon rather than wood since wood is a bundle of many different molecules. Primarily C,H,O and N (probably in that order of abundance, maybe H first)
Carbons has the highest melting point of any element. It bonds very strongly with its self.
Most things will burn at some point. Even metal. Heat a metal high enough in the presence of oxygen and it will form a metal oxide. Every element requires different amount of energy to react with the air. Most metals actually have surfaces that are oxidized. Heat carbon in open air and it will form a carbon oxide. However, this carbon oxide is lighter than air and floats away. The metal oxide is still solid and heavy. Therefore, the oxide layer on a metal forms a sort of barrier to constant oxidation. The oxide on a carbon block could at some point float away exposing more carbon and thus you have a combustion type reaction.
You will melt a material if you introduce enough heat (energy) to overcome the bonding energy but not completely break it. If you keep adding energy you will break the bonding completely and turn it into a gas.
Metallic materials will have a high thermal conductivity and the heat will spread across the whole material rapidly. This way you can break the internal metal-metal bonds without exposing them to the air. Effectively melting it.
Diamond I believe has the best thermal conductivity but it also has super strong bonding energy. But you can melt it at high temp an pressure.
However doing this in air changes things as there is enough energy to have reactions with the air.
Wood:
I do not believe you could ever effectively melt wood. If you had the right pressure, lack of air and heat with wood you would cause reconfiguring of the molecules and develop lower energy formations, thus changing the wood into something probably like oil and natural gas.
3 reasons
1. All organic molecules will break down before carbons melting point.
2. Carbon burns before it hits its melting point
3. Carbon does not have a liquid form at atmospheric pressure
The fact that wood doesn’t melt has to do with it’s particular chemical structure.
Wood is composed of a large number of compounds, but by far the most abundant is cellulose which is a carbohydrate.
Cellulose is in turn composed of extremely long chains of glucose sugars chemically bonded to each other, like a string of beads. There may be tens of thousands of individual glucose units. In chemistry this is known as a Polymer.
You can break cellulose down into individual glucose sugars. There are a number of methods you can use to do this. This is how many fungi get their energy, by digesting wood into simple sugars.
Pure glucose itself melts easily, and is used as an ingredient in candies.
In order to form a liquid, molecules need to be able to easily slide and bump past each other.
This can’t happen with the glucose molecules bound in long chains. Not only that, but the glucose chains are organized into a repeating crystal structure where they fit together like bricks in a brick wall.
Even if one individual glucose molecule is free to wiggle around a little without being unduly attracted by it’s neighbors and jump into a liquid state it’s still restrained at both ends. And this tends to cause it’s inertia to be transferred back down the chain. Those ends are anchored to thousands of other nearby glucose units. The attractive force between adjacent glucose units is much weaker than the chemical bonds linking the glucose chains together. However because the chains are so long and well ordered this keeps any individual glucose molecules from moving out of position.
Therefore wood itself begins to chemically break down, decompose and char well before it will melt. What this really means is that on the whole the force holding the cellulose chains in the solid crystalline matrix is as strong as the chemical bonds in the glucose subunit itself.
This is also true in certain synthetic polymers, depending on their structure. One example is the resin used in heat shields on spacecraft.
However with man-made polymers it’s usually desirable for them to be able to melt, or at least soften to a taffy-like state. This is usually done by limiting the lengths of the chains to, say 100-200 units. This allows them to melt with some effort, but without chemically breaking down. This allows them to be molded into shape easily, or sun and drawn into fibers.
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