Latent heat and phase change question

In summary, a 100g cube of ice at 0 degrees is dropped into 1.0kg of water at 80 degrees. The final temperature of the water after the ice has melted is the unknown variable in the heat flow equation. The initial temperatures for Qwater and Qicewater are 80 degrees and 0 degrees, respectively. The phases involved are ice and water, with the water changing temperature as it gains or loses heat energy. The mass of ice melts and increases its temperature to the final temperature, while the mass of water loses heat and lowers its temperature to the final temperature.
  • #1
mizzy
217
0

Homework Statement


A 100g cube of ice at 0 degrees is dropped into 1.0kg of water that was originally at 80 degrees. What is the final temperature of the water after the ice has melted?


Homework Equations



Q = ml

Q = mc(Tf - Ti)

The Attempt at a Solution


i'm not sure again about the temperature, but this is what i did:


1) Qice = mc (Tf - Ti) where, m = .100kg, c = 2090, Tf = NOT SURE, 80 degrees??, Ti=0

Q = ml where, m = .100kg, L = 3.33 x 10^5

Qicewater = mc (Tf - Ti) where, m = .100, c = 4186, Tf = NOT SURE, Ti = 0

Qwater = mc(Tf - Ti) where, m = 1.0, c = 4186, Tf = ?, Ti = ?


can someone help me please?
 
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  • #2
1st you need to find the latent heat of fusion of water
then water: Tf=? Ti=80
ice: Ti=0 Tf=Tfwater=??
then add up the energys
 
  • #3
I know I'm suppose to add up the energies, but I'm not sure about my temperatures.

what's the final temperature of the ice? Initial temp is 0 degrees, but what's the final?? is it 80 degrees?
 
  • #4
mizzy said:
what's the final temperature of the ice? Initial temp is 0 degrees, but what's the final?? is it 80 degrees?
If the final temperature was 80 degrees, you'd already have your answer!

The trick is that all the water will end up at the same final temperature, which you have to solve for. That's your unknown.

Set up your heat flow equation and solve for Tf.
 
  • #5
but if you look at my first posting...what's the initial temperatures for Qicewater and Qwater?

I always get stumped on temperatures and also on phase changes. FOr example, if a block of ice is put into water, the phases are: ice, ice water, water...right?
 
  • #6
mizzy said:
but if you look at my first posting...what's the initial temperatures for Qicewater and Qwater?
The initial temp for Qwater is given as 80 degrees. When the ice just melts, what is the temp of the water? (Does temperature change during a phase change?)

I always get stumped on temperatures and also on phase changes. FOr example, if a block of ice is put into water, the phases are: ice, ice water, water...right?
I'd just call it ice and water. (But the water changes temperature as it gains/loses heat energy.)

The mass of ice melts, then increases its temperature to the final temperature.

The mass of water loses heat and thus lowers its temperature to the final temperature.
 

1. What is latent heat?

Latent heat is the amount of heat energy required to change the phase of a substance without changing its temperature. This means that when a substance undergoes a phase change, such as from solid to liquid or liquid to gas, energy is either absorbed or released in the form of latent heat.

2. How is latent heat measured?

Latent heat is typically measured in joules (J) or calories (cal). The amount of latent heat needed to change the phase of a substance is specific to that substance and is known as the latent heat of fusion (for a solid to liquid phase change) or the latent heat of vaporization (for a liquid to gas phase change).

3. What is the difference between latent heat and sensible heat?

Sensible heat is the heat energy that causes a change in temperature of a substance. It is measured by a thermometer and can be felt. On the other hand, latent heat does not cause a change in temperature but is instead absorbed or released during a phase change.

4. What factors affect the amount of latent heat needed for a phase change?

The amount of latent heat needed for a phase change depends on the substance and the specific conditions, such as pressure and temperature. The surrounding environment, such as air temperature, can also affect the amount of latent heat needed for a phase change.

5. Why is understanding latent heat important in various industries?

Understanding latent heat is important in industries such as refrigeration, cooking, and materials processing. In refrigeration, latent heat is used to change the phase of a refrigerant, allowing it to absorb heat and cool a space. In cooking, latent heat is used to cook food through the process of boiling or steaming. In materials processing, latent heat is used to control the temperature and phase changes of materials during manufacturing processes.

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