Thermodynamics - Internal energy of state

In summary, the increase in internal energy for the ice is due to an increase in molecular kinetic energy while the increase in internal energy for the liquid water is due to an increase in molecular potential energy and in bonds broken.
  • #1
Jadaav
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1
I had a question :

Heat energy was supplied to melt ice at -15 degree Celsius. But it was not enough to turn the ice completely into water at 0 degrees.

From my calculation I obtained that a mixture of 60% water and 40% ice was produced as a result of heating.

Finally it said to describe the internal energy of that mixture. I couldn't managed to do that part. So I was wandering what was the answer to it.

Also what determines its internal energy ?
 
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  • #2
homework-like questions should be asked in the homework section :)

Energy does work in two different way on substances. Consider a fixed pressure environment where you add energy by heating only. First it heats them up... but then if they reach a transition point, they will stop increasing their temperature and they will use the energy to change phase (if it's sufficient energy for a phase transition) while staying at the same temperature.

You should be able to use that information to answer the question.
 
  • #3
Apply the first law of thermodynamics Q = ΔU + W. Does the process result in any work being done? (assume that there is no change in volume). So how does the change in internal energy, ΔU, relate to the total heat flow, Q?

AM
 
  • #4
Thanks to both of you. :)

Keeping volume and pressure constant, Q = ΔU.

But what's there to describe about the internal energy ?
 
  • #5
Jadaav said:
Thanks to both of you. :)

Keeping volume and pressure constant, Q = ΔU.

But what's there to describe about the internal energy ?

I think the question asks you to describe and quantify the change in internal energy. For the ice the increase in internal energy is in the form of an increase in molecular kinetic energy only. For the liquid water, there has been an increase in molecular kinetic energy and in potential energy (bonds broken).

AM
 
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1. What is internal energy of state?

The internal energy of state is a measure of the total energy of a system at rest. It includes the kinetic energy of the particles within the system and the potential energy of the interactions between particles, such as chemical bonds.

2. How is internal energy of state related to temperature?

The internal energy of state is directly proportional to the temperature of the system. As the temperature increases, the internal energy also increases.

3. What is the difference between internal energy of state and enthalpy?

Internal energy of state refers to the total energy of a system at rest, while enthalpy takes into account the work done by or on the system. Enthalpy is equal to internal energy plus the product of pressure and volume.

4. How does internal energy of state change in a chemical reaction?

In a chemical reaction, the internal energy of state can change due to the formation or breaking of chemical bonds. Exothermic reactions release energy in the form of heat, causing an increase in internal energy, while endothermic reactions absorb energy, resulting in a decrease in internal energy.

5. Can internal energy of state be measured?

Yes, internal energy of state can be measured using various techniques such as calorimetry, which measures the heat transfer in a system, or by measuring changes in temperature and volume. However, it is not possible to directly measure the internal energy of a system, only changes in internal energy can be measured.

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