Does Temperature Equalize Between Iron and Wood in Thermal Equilibrium?

In summary, in an isolated container, thermal equilibrium means a uniform temperature but not a uniform energy distribution. The mean kinetic energy of the atoms in wood and iron will be the same, but there may be differences in other forms of energy due to differences in heat capacity. When a system reaches thermodynamic equilibrium, there is no longer a transfer of energy, but this does not mean that the equilibrium state is continuous. The temperature in thermal equilibrium is determined by the mean kinetic energy of the atoms. Energy flow between materials in thermal equilibrium is generally referred to as heat energy.
  • #1
Outrageous
374
0
If I put an iron of 350K and a wood of 300K in contact, then put them in a container so that they are adiabatic. The question : after a very long time will they become thermal equilibrium? same temperature?
My guess : they should be same. But they have different specific heat capacities. If the specific heat capacity of wood is larger . Then in order to achieve same temperature, a lot of heat will flow to the wood.
(a bit not logic) when they are in thermal equilibrium mean that they have same temperature but the heat energy of wood is higher then iron?

Thank you
 
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  • #2
This is in an isolated container, so thermal equilibrium means "uniform temperature". It never means "uniform energy".
 
  • #3
But why the energy will not get equilibrium? Isn't the temperature of wood and iron also depend on heat energy inside? Then what makes the energy flow from the iron to wood? Because it is no longer due to concentration of gradient of energy between them?
 
  • #4
Temperature is the Mean Kinetic Energy; that is what will reach equilibrium. It's basic thermodynamics. The distribution of other forms of energy will depend upon the specific circumstances.
 
  • #5
So do you mean the mean kinetic energy of wood atoms and iron atoms will be the same?:smile:
 
  • #6
Outrageous said:
But why the energy will not get equilibrium? Isn't the temperature of wood and iron also depend on heat energy inside? Then what makes the energy flow from the iron to wood? Because it is no longer due to concentration of gradient of energy between them?

A first step towards understanding this (in my opinion) is by learning the concept of enthalpy and, in a later step, entropy. The energy will also reach an equilibrium state, but this does not mean that the equilibrium state is uniform over the different materials.
 
  • #7
Outrageous said:
So do you mean the mean kinetic energy of wood atoms and iron atoms will be the same?:smile:

Hm. As they are solids, there will not be a lot of translational KE in the atoms themselves (by definition?) but there is KE in the free electrons in metals and also the vibrational KE. I realize that a lot of thermodynamic arguments seem to assume we're talking of gases.

@bigfoot
I presume you aren't implying a continuous flow of energy, when you say the equilibrium state is not continuous. Can you explain?
 
  • #8
When the system is in thermodynamic equilibrium, it has reached a steady state and there is no transfer of energy anymore. In this equilibrium, the temperature is the same for both wood and iron. Enthalpy for instance has also reached a constant, steady state value, but it is different (higher) for wood than for iron because of the difference in heat capacity. So there is an enthalpy jump at the interface between the wood and the iron.
 
  • #9
bigfooted said:
When the system is in thermodynamic equilibrium, it has reached a steady state and there is no transfer of energy anymore.

Lack of transfer of energy doesn't follow from the steady state condition. That's why I signaled "isolated container".
 
  • #10
I don't understand that exactly. I think it's the double negative that's throwing me. Equilibrium must mean no energy transfer, surely?
 
  • #11
No, you can have a steady state with a transport going on. Imagine a rod connecting a heat source and a heat sink - assuming temperatures of the source and the sink are constant temperature gradient in the rod is constant as well. There is a steady state in the rod, but the heat is being transported.
 
  • #12
I am confused as well, can I ask again when wood and iron reach equilibrium, the temperature will be the same,what makes the temperature same? Is the mean kinetic energy, (3/2)kT?

Then what is the energy flow out from iron to wood should I call? Heat energy? Or potential energy or total energy ?
 

1. What is the melting point of iron and wood?

The melting point of iron is 1538 degrees Celsius (2800 degrees Fahrenheit) and the melting point of wood varies depending on the type of wood, but it is generally between 180-225 degrees Celsius (356-437 degrees Fahrenheit).

2. How does the temperature affect the strength of iron and wood?

As temperature increases, the strength of iron decreases due to the metal becoming more malleable. In contrast, the strength of wood increases with temperature up to a certain point, after which it starts to weaken and lose its structural integrity.

3. What is the coefficient of thermal expansion for iron and wood?

The coefficient of thermal expansion for iron is 11.8 x 10^-6 per degree Celsius, while for wood it varies depending on the type of wood, but it is generally between 30-60 x 10^-6 per degree Celsius.

4. How does the temperature affect the color of iron and wood?

As iron is heated, it changes color from a dull red to a bright orange, and eventually to a white glow at high temperatures. Wood, on the other hand, may darken or char at high temperatures due to the release of gases and the breakdown of its organic compounds.

5. Can extreme temperatures cause damage to iron and wood?

Yes, extreme temperatures can cause damage to both iron and wood. High temperatures can cause iron to melt or warp, while low temperatures can cause it to become brittle. Wood can also become damaged at extreme temperatures, with high temperatures causing it to burn or char and low temperatures causing it to become brittle and potentially crack.

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