Heat of Transformation: Does It Affect Temperature?

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Discussion Overview

The discussion revolves around the concept of heat of transformation and its effect on temperature during phase changes, specifically focusing on the melting of ice and the energy involved in such processes. Participants explore the relationship between energy input, phase changes, and temperature stability.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related

Main Points Raised

  • Some participants assert that the temperature remains constant during a phase change, such as melting ice at 0°C, despite the input of energy.
  • One participant notes that the energy required for the phase change goes into breaking the molecular lattice of the solid, rather than increasing temperature.
  • Another participant agrees that while energy raises temperature until a phase change occurs, additional energy is needed to facilitate the transformation without changing temperature.
  • It is proposed that the energy used during the phase change is stored as potential energy until the substance freezes again, at which point it is released as heat.
  • A homework example is presented to illustrate the concept, questioning how energy transfer affects the melting of ice in water at different temperatures.
  • Some participants emphasize that the energy added during phase changes is not used to increase temperature but rather to change the state of the substance.

Areas of Agreement / Disagreement

Participants generally agree that temperature does not increase during phase changes, but there are varying interpretations of how energy is utilized in these processes. The discussion remains unresolved regarding the implications of energy transfer and its relationship to temperature and phase changes.

Contextual Notes

Participants express uncertainty about the specifics of energy transfer during phase changes and the definitions of temperature and energy in this context. The discussion includes assumptions about the behavior of substances at phase change points that are not fully explored.

Who May Find This Useful

This discussion may be useful for students and individuals interested in thermodynamics, phase transitions, and the principles of heat transfer in physical chemistry and physics.

1MileCrash
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What happens to the heat required in heat of transformation?

It doesn't actually raise the temperature of the substance does it?

IE if I have ice at 0*C and I input the exact energy required to melt it, it's still 0*C?
 
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To my knowledge the temperature stays the same while the material undergoes a phase change.
 
It goes into the lattice.

Temperature is a statistic of microscopic particles, it doesn't mean energy.
 
I agree that temperature isn't energy, but I'm talking about the energy required for the phase-change. Seeing that the addition of energy does imply a change in temperature until the melting point in which it goes into the required heat of transformation, I wondered where it "actually" went.

But I think I understand your answer, energy will raise the temperature until a certain point, but additional energy is then required to break the molecular lattice. Correct?
 
Ye correct.
 
And the same energy is stored as potential energy until the object freezes again and reforms the lattice, releasing that energy as heat again?

Thanks, this will let me do problems like this more confidently.
 
For example (this is a homework problem but it is merely to demonstrate)

Fifty grams of ice at 0°C is placed in a thermos bottle containing one hundred grams of water at 6°C. How many grams of ice will melt? The heat of fusion of water is 333 kJ/kg and the specific heat is 4190 J/kg


After all of that happens, equilibrium pressure is still just 0*, because all the energy the *6 water went into breaking (a fraction of) the ice's lattice?
 
The energy that goes into turning ice at 0°C into water at 0°C goes into breaking the bonds between the water molecules that form the ice. Temperature is energy. It's the product of the kinetic energy of the particles.
 
yes. the energy added is used only to change its phase from solid to liquid but not used to raise its temperature from 0*C. Same thing goes when you vaporize water at let's say 110*C, you add heat to change its phase from liquid to gas at constant temperature. :)
 

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