Latent heat of fusion for water question

In summary: Some of the water will become a solid, and some will remain as a liquid. The liquid water will have a temperature increase no more than to 0C as heat is released from the freezing part of water, which also ends up at 0C.
  • #1
soronemus
13
0
Hello,

I am doing some research involving supercooled water flash freezing into ice.

I am doing some calculations and I think that I must be wrong judging by my result.

Using the latent heat of fusion of water, and the specific heat of water, I can calculate a temperature value which should be the amount that the water heats up due to the energy released by the exothermic reaction of water turning into ice. This value was 79 degrees Celsius. This seems very unrealistic to me... According to that the water would jump from freezing almost to boiling. Am I doing something wrong?

Calculations: (4.2J/gC)/(334J/g) = 1/0.0125C ~79C
(latent heat of fusion / specific heat)
 
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  • #2
soronemus said:
(4.2J/gC)/(334J/g) = 1/0.0125C ~79C
You might try this again.
 
  • #3
I guess I don't see what I did wrong. Would you elaborate?
 
  • #4
soronemus said:
Would you elaborate?
4.21/334 = 79? Think about it a moment.
 
  • #5
4.21/334 is not 79 you are correct, it is .0125. The problem is that I still have the C unit left in the denominator when everything else cancels. I would think that you would have to take the inverse of .0125 (79) to get the temperature unit into the numerator and get my answer. My notation on my original post was kind of bad.
 
  • #6
Specific heat will be in J/gC for one thing. You are supercooling liquid water; the only heat you have to account for is that removed to reduce the temperature below the freezing point. The only temperature rise in the system is from the supercooled temperature to the freezing temperature. That temperature difference times specific heat divided by latent heat will give you the total mass of solid you can form.
 
  • #7
I did use J/gC for specific heat. The operation you are proposing cancels all units and leaves you with a dimensionless number if i am looking at it correctly. Thank you for trying to help, I think we might be on different pages. I found something more geared towards what I'm looking for here. http://www.phy.mtu.edu/~cantrell/agu2009-PosterSzedlakV5.pdf
Would you suggest any other resources on the subject?
 
  • #8
soronemus said:
Would you suggest any other resources on the subject?
Do a Hess's Law cycle, or pair of cycles in parallel, summing heats for equilibrium freezing, and comparing that sum to a supercooling cycle to see where you're losing/gaining a latent heat term to "boil" water.
 
  • #9
soronemus said:
I did use J/gC for specific heat. The operation you are proposing cancels all units and leaves you with a dimensionless number if i am looking at it correctly. Thank you for trying to help, I think we might be on different pages. I found something more geared towards what I'm looking for here. http://www.phy.mtu.edu/~cantrell/agu2009-PosterSzedlakV5.pdf
Would you suggest any other resources on the subject?
Some of the water will become a solid, and some will remain as a liquid. The liquid water will have a temperature increase no more than to 0C as heat is released from the freezing part of water, which also ends up at 0C.

You can read this lab example to get the idea.
http://www.colorado.edu/MCEN/flowvis/galleries/2011/Team-1/Reports/Schollenberger_Scott.pdf
 

Related to Latent heat of fusion for water question

1. What is the latent heat of fusion for water?

The latent heat of fusion for water is the amount of energy required to melt one gram of ice at its melting point of 0°C. It is also the amount of energy released when one gram of liquid water freezes into ice at 0°C.

2. How is the latent heat of fusion for water calculated?

The latent heat of fusion for water is calculated by multiplying the mass of the substance by its specific heat and its change in temperature. For water, the specific heat is 334 J/g·°C, and the change in temperature is 0°C (from solid ice at 0°C to liquid water at 0°C).

3. Why is the latent heat of fusion for water important?

The latent heat of fusion for water is important because it plays a crucial role in the Earth's climate and weather. It helps regulate temperature changes and is a major contributor to the Earth's water cycle.

4. How does the latent heat of fusion for water affect everyday life?

The latent heat of fusion for water affects our everyday lives in many ways. It allows us to use ice to cool drinks or preserve food, and it also helps regulate the temperature of our homes and buildings through the use of air conditioners and heaters.

5. Can the latent heat of fusion for water vary?

Yes, the latent heat of fusion for water can vary slightly depending on factors such as pressure and impurities in the water. However, these variations are minimal and do not significantly impact its overall value.

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