Change in entropy of system and universe

In summary: This would result in a decrease in entropy of the freezer, as the system reaches thermal equilibrium. In summary, when 50.0g of water at 30C is frozen to ice at -10C in a freezer with constant volume, the change in entropy for the system can be calculated using the equation ΔS=Q/T=∫Ti..Tf(CpdT)/T. To calculate the change in entropy of the thermal universe, we must also consider the freezer, which can be assumed to have a constant temperature during the process. This results in
  • #1
sfgoat
10
0

Homework Statement



50.0g of water (the system) at 30C is frozen to ice at a final temp of -10C in a freezer. Assuming that the volume of water remains the same during the process, calculate the change in entropy of the system and the change of entropy of the thermal universe when the system reaches thermal equilibrium.
constants.jpg


Homework Equations


ΔS=Q/T=∫Ti..Tf(CpdT)/T

The Attempt at a Solution


See attached image for attempt at solution. I already missed the question in class and just want to know how to properly do it at this point. Thanks.
CCI11212014_0001.jpg
 
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  • #2
sfgoat said:

Homework Statement



50.0g of water (the system) at 30C is frozen to ice at a final temp of -10C in a freezer. Assuming that the volume of water remains the same during the process, calculate the change in entropy of the system and the change of entropy of the thermal universe when the system reaches thermal equilibrium.

Homework Equations


ΔS=Q/T=∫Ti..Tf(CpdT)/T
This is correct for the entropy change for the water. What about the ice part?
 
  • #3
sfgoat said:

Homework Statement



50.0g of water (the system) at 30C is frozen to ice at a final temp of -10C in a freezer. Assuming that the volume of water remains the same during the process, calculate the change in entropy of the system and the change of entropy of the thermal universe when the system reaches thermal equilibrium.
View attachment 75716

Homework Equations


ΔS=Q/T=∫Ti..Tf(CpdT)

In order to calculate the change in entropy of the freezer (i.e the surroundings) assume that the freezer is so large that its temperature does not change during the process. In that case, the change in entropy is -Q/Tfreezer where Q is the heat flow out of the water. What is the heat flow out of the water?

AM
 

1. What is entropy and how does it relate to change in a system?

Entropy is a measure of the disorder or randomness in a system. A change in entropy occurs when energy is transferred or transformed within a system, which can result in an increase or decrease in disorder. This change in entropy is related to the amount of energy that is dispersed or unavailable to do work.

2. How does the change in entropy of a system affect the universe?

The change in entropy of a system can also have an impact on the universe as a whole. According to the second law of thermodynamics, the total entropy of the universe is always increasing. This means that as a system becomes more disordered, the universe becomes more disordered as well.

3. Can the entropy of a system decrease?

Yes, the entropy of a system can decrease. This can happen when energy is transferred into the system, allowing it to become more ordered. However, this decrease in entropy must always be accompanied by an increase in entropy in the surroundings or the universe as a whole.

4. How does temperature affect the change in entropy of a system?

Temperature plays a significant role in the change in entropy of a system. An increase in temperature can result in an increase in entropy, as the molecules in the system have more energy and are more likely to be in a disordered state. Conversely, a decrease in temperature can lead to a decrease in entropy, as the molecules have less energy and are more likely to be in an ordered state.

5. Can the change in entropy of a system be reversed?

Theoretically, yes, the change in entropy of a system can be reversed. However, in order to do so, an external energy source must be used, which will result in an increase in entropy in another part of the system or the surroundings. This is known as the principle of energy conservation and is a fundamental principle of thermodynamics.

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